Restart the tick when necessary from the irq exit path. It makes nohz
full more flexible, simplify the related IPIs and doesn't bring
significant overhead on irq exit.
In a longer term view, it will allow us to piggyback the nohz kick
on the scheduler IPI in the future instead of sending a dedicated IPI
that often doubles the scheduler IPI on task wakeup. This will require
more changes though including careful review of resched_curr() callers
to include nohz full needs.
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
On nohz full early days, idle dynticks and full dynticks weren't well
integrated and we couldn't risk full dynticks calls on idle without
risking messing up tick idle statistics. This is why we prevented such
thing to happen.
Nowadays full dynticks and idle dynticks are better integrated and
interact without known issue.
So lets remove that.
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
HZ never goes much further 1000 and a bit. And if we ever reach one tick
per microsecond, we might be having a problem.
Lets stop maintaining this special case, just leave a paranoid check.
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc; John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
tick_broadcast_oneshot_control got moved from tick-broadcast to
tick-common, but the export stayed in the old place. Fix it up.
Fixes: f32dd11705 'tick/broadcast: Make idle check independent from mode and config'
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Dan reported that the recent changes to the broadcast code introduced
a potential NULL dereference.
Add the proper check.
Fixes: e045431190 "tick/broadcast: Sanity check the shutdown of the local clock_event"
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Andriy reported that on a virtual machine the warning about negative
expiry time in the clock events programming code triggered:
hpet: hpet0 irq 40 for MSI
hpet: hpet1 irq 41 for MSI
Switching to clocksource hpet
WARNING: at kernel/time/clockevents.c:239
[<ffffffff810ce6eb>] clockevents_program_event+0xdb/0xf0
[<ffffffff810cf211>] tick_handle_periodic_broadcast+0x41/0x50
[<ffffffff81016525>] timer_interrupt+0x15/0x20
When the second hpet is installed as a per cpu timer the broadcast
event is not longer required and stopped, which sets the next_evt of
the broadcast device to KTIME_MAX.
If after that a spurious interrupt happens on the broadcast device,
then the current code blindly handles it and tries to reprogram the
broadcast device afterwards, which adds the period to
next_evt. KTIME_MAX + period results in a negative expiry value
causing the WARN_ON in the clockevents code to trigger.
Add a proper check for the state of the broadcast device into the
interrupt handler and return if the interrupt is spurious.
[ Folded in pointer fix from Sudeep ]
Reported-by: Andriy Gapon <avg@FreeBSD.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20150705205221.802094647@linutronix.de
If the current cpu is the one which has the hrtimer based broadcast
queued then we better return busy immediately instead of going through
loops and hoops to figure that out.
[ Split out from a larger combo patch ]
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
Tell the idle code not to go deep if the broadcast IPI is about to
arrive.
[ Split out from a larger combo patch ]
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
If the system is in periodic mode and the broadcast device is hrtimer
based, return busy as we have no proper handling for this.
[ Split out from a larger combo patch ]
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
We need to check more than the periodic mode for proper operation in
all runtime combinations. To avoid code duplication move the check
into the enter state handling.
No functional change.
[ Split out from a larger combo patch ]
Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
Add a check for a installed broadcast device to the oneshot control
function and return busy if not.
[ Split out from a larger combo patch ]
Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
Currently the broadcast busy check, which prevents the idle code from
going into deep idle, works only in one shot mode.
If NOHZ and HIGHRES are off (config or command line) there is no
sanity check at all, so under certain conditions cpus are allowed to
go into deep idle, where the local timer stops, and are not woken up
again because there is no broadcast timer installed or a hrtimer based
broadcast device is not evaluated.
Move tick_broadcast_oneshot_control() into the common code and provide
proper subfunctions for the various config combinations.
The common check in tick_broadcast_oneshot_control() is for the C3STOP
misfeature flag of the local clock event device. If its not set, idle
can proceed. If set, further checks are necessary.
Provide checks for the trivial cases:
- If broadcast is disabled in the config, then return busy
- If oneshot mode (NOHZ/HIGHES) is disabled in the config, return
busy if the broadcast device is hrtimer based.
- If oneshot mode is enabled in the config call the original
tick_broadcast_oneshot_control() function. That function needs
extra checks which will be implemented in seperate patches.
[ Split out from a larger combo patch ]
Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
The broadcast code shuts down the local clock event unconditionally
even if no broadcast device is installed or if the broadcast device is
hrtimer based.
Add proper sanity checks.
[ Split out from a larger combo patch ]
Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
The hrtimer based broadcast vehicle can cause a hrtimer recursion
which went unnoticed until we changed the hrtimer expiry code to keep
track of the currently running timer.
local_timer_interrupt()
local_handler()
hrtimer_interrupt()
expire_hrtimers()
broadcast_hrtimer()
send_ipis()
local_handler()
hrtimer_interrupt()
....
Solution is simple: Prevent the local handler call from the broadcast
code when the broadcast 'device' is hrtimer based.
[ Split out from a larger combo patch ]
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
Its mandatory for the drivers to provide set_state_{oneshot|periodic}()
(only if related modes are supported) and set_state_shutdown() callbacks
today, if they are implementing the new set-state interface.
But this leads to unnecessary noop callbacks for drivers which don't
want to implement them. Over that, it will lead to a full function call
for nothing really useful.
Lets make all set-state callbacks optional.
Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/1436256875-15562-1-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The RCU_USER_QS Kconfig parameter is now just a synonym for NO_HZ_FULL,
so this commit eliminates RCU_USER_QS, replacing all uses with NO_HZ_FULL.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Pull timer fixes from Thomas Gleixner:
"This contains:
- a build regression fix introduced by the timeconst move
- a hotplug regression fix introduced by the timer wheel diet
- a cpu hotplug bug fix for the exynos clocksource driver"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Remove development rules from Kbuild/Makefile
timer: Fix hotplug regression
clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier
Main excitement here is Peter Zijlstra's lockless rbtree optimization to
speed module address lookup. He found some abusers of the module lock
doing that too.
A little bit of parameter work here too; including Dan Streetman's breaking
up the big param mutex so writing a parameter can load another module (yeah,
really). Unfortunately that broke the usual suspects, !CONFIG_MODULES and
!CONFIG_SYSFS, so those fixes were appended too.
Cheers,
Rusty.
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Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module updates from Rusty Russell:
"Main excitement here is Peter Zijlstra's lockless rbtree optimization
to speed module address lookup. He found some abusers of the module
lock doing that too.
A little bit of parameter work here too; including Dan Streetman's
breaking up the big param mutex so writing a parameter can load
another module (yeah, really). Unfortunately that broke the usual
suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were
appended too"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits)
modules: only use mod->param_lock if CONFIG_MODULES
param: fix module param locks when !CONFIG_SYSFS.
rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
module: add per-module param_lock
module: make perm const
params: suppress unused variable error, warn once just in case code changes.
modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'.
kernel/module.c: avoid ifdefs for sig_enforce declaration
kernel/workqueue.c: remove ifdefs over wq_power_efficient
kernel/params.c: export param_ops_bool_enable_only
kernel/params.c: generalize bool_enable_only
kernel/module.c: use generic module param operaters for sig_enforce
kernel/params: constify struct kernel_param_ops uses
sysfs: tightened sysfs permission checks
module: Rework module_addr_{min,max}
module: Use __module_address() for module_address_lookup()
module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING
module: Optimize __module_address() using a latched RB-tree
rbtree: Implement generic latch_tree
seqlock: Introduce raw_read_seqcount_latch()
...
time.o gets rebuilt unconditionally due to a leftover Makefile rule
which was placed there for development purposes.
Remove it along with the commented out always rule in the toplevel
Kbuild file.
Fixes: 0a227985d4 'time: Move timeconst.h into include/generated'
Reported-by; Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
The recent timer wheel rework removed the get/put_cpu_var() pair in
the hotplug migration code, which results in:
BUG: using smp_processor_id() in preemptible [00000000] code: hib.sh/2845
...
[<ffffffff810d4fa3>] timer_cpu_notify+0x53/0x12
That hunk is a leftover from an earlier iteration and went unnoticed
so far.
Restore the previous code which was obviously correct.
Fixes: 0eeda71bc3 'timer: Replace timer base by a cpu index'
Reported-and_tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
- ACPICA update to upstream revision 20150515 including basic
support for ACPI 6 features: new ACPI tables introduced by
ACPI 6 (STAO, XENV, WPBT, NFIT, IORT), changes related to the
other tables (DTRM, FADT, LPIT, MADT), new predefined names
(_BTH, _CR3, _DSD, _LPI, _MTL, _PRR, _RDI, _RST, _TFP, _TSN),
fixes and cleanups (Bob Moore, Lv Zheng).
- ACPI device power management core code update to follow ACPI 6
which reflects the ACPI device power management implementation
in Windows (Rafael J Wysocki).
- Rework of the backlight interface selection logic to reduce the
number of kernel command line options and improve the handling
of DMI quirks that may be involved in that and to make the
code generally more straightforward (Hans de Goede).
- Fixes for the ACPI Embedded Controller (EC) driver related to
the handling of EC transactions (Lv Zheng).
- Fix for a regression related to the ACPI resources management
and resulting from a recent change of ACPI initialization code
ordering (Rafael J Wysocki).
- Fix for a system initialization regression related to ACPI
introduced during the 3.14 cycle and caused by running the
code that switches the platform over to the ACPI mode too
early in the initialization sequence (Rafael J Wysocki).
- Support for the ACPI _CCA device configuration object related
to DMA cache coherence (Suravee Suthikulpanit).
- ACPI/APEI fixes and cleanups (Jiri Kosina, Borislav Petkov).
- ACPI battery driver cleanups (Luis Henriques, Mathias Krause).
- ACPI processor driver cleanups (Hanjun Guo).
- Cleanups and documentation update related to the ACPI device
properties interface based on _DSD (Rafael J Wysocki).
- ACPI device power management fixes (Rafael J Wysocki).
- Assorted cleanups related to ACPI (Dominik Brodowski. Fabian
Frederick, Lorenzo Pieralisi, Mathias Krause, Rafael J Wysocki).
- Fix for a long-standing issue causing General Protection Faults
to be generated occasionally on return to user space after resume
from ACPI-based suspend-to-RAM on 32-bit x86 (Ingo Molnar).
- Fix to make the suspend core code return -EBUSY consistently in
all cases when system suspend is aborted due to wakeup detection
(Ruchi Kandoi).
- Support for automated device wakeup IRQ handling allowing drivers
to make their PM support more starightforward (Tony Lindgren).
- New tracepoints for suspend-to-idle tracing and rework of the
prepare/complete callbacks tracing in the PM core (Todd E Brandt,
Rafael J Wysocki).
- Wakeup sources framework enhancements (Jin Qian).
- New macro for noirq system PM callbacks (Grygorii Strashko).
- Assorted cleanups related to system suspend (Rafael J Wysocki).
- cpuidle core cleanups to make the code more efficient (Rafael J
Wysocki).
- powernv/pseries cpuidle driver update (Shilpasri G Bhat).
- cpufreq core fixes related to CPU online/offline that should
reduce the overhead of these operations quite a bit, unless the
CPU in question is physically going away (Viresh Kumar, Saravana
Kannan).
- Serialization of cpufreq governor callbacks to avoid race
conditions in some cases (Viresh Kumar).
- intel_pstate driver fixes and cleanups (Doug Smythies, Prarit
Bhargava, Joe Konno).
- cpufreq driver (arm_big_little, cpufreq-dt, qoriq) updates (Sudeep
Holla, Felipe Balbi, Tang Yuantian).
- Assorted cleanups in cpufreq drivers and core (Shailendra Verma,
Fabian Frederick, Wang Long).
- New Device Tree bindings for representing Operating Performance
Points (Viresh Kumar).
- Updates for the common clock operations support code in the PM
core (Rajendra Nayak, Geert Uytterhoeven).
- PM domains core code update (Geert Uytterhoeven).
- Intel Knights Landing support for the RAPL (Running Average Power
Limit) power capping driver (Dasaratharaman Chandramouli).
- Fixes related to the floor frequency setting on Atom SoCs in the
RAPL power capping driver (Ajay Thomas).
- Runtime PM framework documentation update (Ben Dooks).
- cpupower tool fix (Herton R Krzesinski).
/
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Merge tag 'pm+acpi-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management and ACPI updates from Rafael Wysocki:
"The rework of backlight interface selection API from Hans de Goede
stands out from the number of commits and the number of affected
places perspective. The cpufreq core fixes from Viresh Kumar are
quite significant too as far as the number of commits goes and because
they should reduce CPU online/offline overhead quite a bit in the
majority of cases.
From the new featues point of view, the ACPICA update (to upstream
revision 20150515) adding support for new ACPI 6 material to ACPICA is
the one that matters the most as some new significant features will be
based on it going forward. Also included is an update of the ACPI
device power management core to follow ACPI 6 (which in turn reflects
the Windows' device PM implementation), a PM core extension to support
wakeup interrupts in a more generic way and support for the ACPI _CCA
device configuration object.
The rest is mostly fixes and cleanups all over and some documentation
updates, including new DT bindings for Operating Performance Points.
There is one fix for a regression introduced in the 4.1 cycle, but it
adds quite a number of lines of code, it wasn't really ready before
Thursday and you were on vacation, so I refrained from pushing it on
the last minute for 4.1.
Specifics:
- ACPICA update to upstream revision 20150515 including basic support
for ACPI 6 features: new ACPI tables introduced by ACPI 6 (STAO,
XENV, WPBT, NFIT, IORT), changes related to the other tables (DTRM,
FADT, LPIT, MADT), new predefined names (_BTH, _CR3, _DSD, _LPI,
_MTL, _PRR, _RDI, _RST, _TFP, _TSN), fixes and cleanups (Bob Moore,
Lv Zheng).
- ACPI device power management core code update to follow ACPI 6
which reflects the ACPI device power management implementation in
Windows (Rafael J Wysocki).
- rework of the backlight interface selection logic to reduce the
number of kernel command line options and improve the handling of
DMI quirks that may be involved in that and to make the code
generally more straightforward (Hans de Goede).
- fixes for the ACPI Embedded Controller (EC) driver related to the
handling of EC transactions (Lv Zheng).
- fix for a regression related to the ACPI resources management and
resulting from a recent change of ACPI initialization code ordering
(Rafael J Wysocki).
- fix for a system initialization regression related to ACPI
introduced during the 3.14 cycle and caused by running the code
that switches the platform over to the ACPI mode too early in the
initialization sequence (Rafael J Wysocki).
- support for the ACPI _CCA device configuration object related to
DMA cache coherence (Suravee Suthikulpanit).
- ACPI/APEI fixes and cleanups (Jiri Kosina, Borislav Petkov).
- ACPI battery driver cleanups (Luis Henriques, Mathias Krause).
- ACPI processor driver cleanups (Hanjun Guo).
- cleanups and documentation update related to the ACPI device
properties interface based on _DSD (Rafael J Wysocki).
- ACPI device power management fixes (Rafael J Wysocki).
- assorted cleanups related to ACPI (Dominik Brodowski, Fabian
Frederick, Lorenzo Pieralisi, Mathias Krause, Rafael J Wysocki).
- fix for a long-standing issue causing General Protection Faults to
be generated occasionally on return to user space after resume from
ACPI-based suspend-to-RAM on 32-bit x86 (Ingo Molnar).
- fix to make the suspend core code return -EBUSY consistently in all
cases when system suspend is aborted due to wakeup detection (Ruchi
Kandoi).
- support for automated device wakeup IRQ handling allowing drivers
to make their PM support more starightforward (Tony Lindgren).
- new tracepoints for suspend-to-idle tracing and rework of the
prepare/complete callbacks tracing in the PM core (Todd E Brandt,
Rafael J Wysocki).
- wakeup sources framework enhancements (Jin Qian).
- new macro for noirq system PM callbacks (Grygorii Strashko).
- assorted cleanups related to system suspend (Rafael J Wysocki).
- cpuidle core cleanups to make the code more efficient (Rafael J
Wysocki).
- powernv/pseries cpuidle driver update (Shilpasri G Bhat).
- cpufreq core fixes related to CPU online/offline that should reduce
the overhead of these operations quite a bit, unless the CPU in
question is physically going away (Viresh Kumar, Saravana Kannan).
- serialization of cpufreq governor callbacks to avoid race
conditions in some cases (Viresh Kumar).
- intel_pstate driver fixes and cleanups (Doug Smythies, Prarit
Bhargava, Joe Konno).
- cpufreq driver (arm_big_little, cpufreq-dt, qoriq) updates (Sudeep
Holla, Felipe Balbi, Tang Yuantian).
- assorted cleanups in cpufreq drivers and core (Shailendra Verma,
Fabian Frederick, Wang Long).
- new Device Tree bindings for representing Operating Performance
Points (Viresh Kumar).
- updates for the common clock operations support code in the PM core
(Rajendra Nayak, Geert Uytterhoeven).
- PM domains core code update (Geert Uytterhoeven).
- Intel Knights Landing support for the RAPL (Running Average Power
Limit) power capping driver (Dasaratharaman Chandramouli).
- fixes related to the floor frequency setting on Atom SoCs in the
RAPL power capping driver (Ajay Thomas).
- runtime PM framework documentation update (Ben Dooks).
- cpupower tool fix (Herton R Krzesinski)"
* tag 'pm+acpi-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (194 commits)
cpuidle: powernv/pseries: Auto-promotion of snooze to deeper idle state
x86: Load __USER_DS into DS/ES after resume
PM / OPP: Add binding for 'opp-suspend'
PM / OPP: Allow multiple OPP tables to be passed via DT
PM / OPP: Add new bindings to address shortcomings of existing bindings
ACPI: Constify ACPI device IDs in documentation
ACPI / enumeration: Document the rules regarding the PRP0001 device ID
ACPI / video: Make acpi_video_unregister_backlight() private
acpi-video-detect: Remove old API
toshiba-acpi: Port to new backlight interface selection API
thinkpad-acpi: Port to new backlight interface selection API
sony-laptop: Port to new backlight interface selection API
samsung-laptop: Port to new backlight interface selection API
msi-wmi: Port to new backlight interface selection API
msi-laptop: Port to new backlight interface selection API
intel-oaktrail: Port to new backlight interface selection API
ideapad-laptop: Port to new backlight interface selection API
fujitsu-laptop: Port to new backlight interface selection API
eeepc-laptop: Port to new backlight interface selection API
dell-wmi: Port to new backlight interface selection API
...
Pull timer updates from Thomas Gleixner:
"A rather largish update for everything time and timer related:
- Cache footprint optimizations for both hrtimers and timer wheel
- Lower the NOHZ impact on systems which have NOHZ or timer migration
disabled at runtime.
- Optimize run time overhead of hrtimer interrupt by making the clock
offset updates smarter
- hrtimer cleanups and removal of restrictions to tackle some
problems in sched/perf
- Some more leap second tweaks
- Another round of changes addressing the 2038 problem
- First step to change the internals of clock event devices by
introducing the necessary infrastructure
- Allow constant folding for usecs/msecs_to_jiffies()
- The usual pile of clockevent/clocksource driver updates
The hrtimer changes contain updates to sched, perf and x86 as they
depend on them plus changes all over the tree to cleanup API changes
and redundant code, which got copied all over the place. The y2038
changes touch s390 to remove the last non 2038 safe code related to
boot/persistant clock"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits)
clocksource: Increase dependencies of timer-stm32 to limit build wreckage
timer: Minimize nohz off overhead
timer: Reduce timer migration overhead if disabled
timer: Stats: Simplify the flags handling
timer: Replace timer base by a cpu index
timer: Use hlist for the timer wheel hash buckets
timer: Remove FIFO "guarantee"
timers: Sanitize catchup_timer_jiffies() usage
hrtimer: Allow hrtimer::function() to free the timer
seqcount: Introduce raw_write_seqcount_barrier()
seqcount: Rename write_seqcount_barrier()
hrtimer: Fix hrtimer_is_queued() hole
hrtimer: Remove HRTIMER_STATE_MIGRATE
selftest: Timers: Avoid signal deadlock in leap-a-day
timekeeping: Copy the shadow-timekeeper over the real timekeeper last
clockevents: Check state instead of mode in suspend/resume path
selftests: timers: Add leap-second timer edge testing to leap-a-day.c
ntp: Do leapsecond adjustment in adjtimex read path
time: Prevent early expiry of hrtimers[CLOCK_REALTIME] at the leap second edge
ntp: Introduce and use SECS_PER_DAY macro instead of 86400
...
If nohz is disabled on the kernel command line the [hr]timer code
still calls wake_up_nohz_cpu() and tick_nohz_full_cpu(), a pretty
pointless exercise. Cache nohz_active in [hr]timer per cpu bases and
avoid the overhead.
Before:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu
After:
48.73% hog [.] main
15.36% [kernel] [k] _raw_spin_lock_irqsave
9.77% [kernel] [k] _raw_spin_unlock_irqrestore
6.61% [kernel] [k] lock_timer_base.isra.38
6.42% [kernel] [k] mod_timer
3.90% [kernel] [k] detach_if_pending
3.76% [kernel] [k] del_timer
2.41% [kernel] [k] internal_add_timer
1.39% [kernel] [k] __internal_add_timer
0.76% [kernel] [k] timerfn
We probably should have a cached value for nohz full in the per cpu
bases as well to avoid the cpumask check. The base cache line is hot
already, the cpumask not necessarily.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.207378134@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Eric reported that the timer_migration sysctl is not really nice
performance wise as it needs to check at every timer insertion whether
the feature is enabled or not. Further the check does not live in the
timer code, so we have an extra function call which checks an extra
cache line to figure out that it is disabled.
We can do better and store that information in the per cpu (hr)timer
bases. I pondered to use a static key, but that's a nightmare to
update from the nohz code and the timer base cache line is hot anyway
when we select a timer base.
The old logic enabled the timer migration unconditionally if
CONFIG_NO_HZ was set even if nohz was disabled on the kernel command
line.
With this modification, we start off with migration disabled. The user
visible sysctl is still set to enabled. If the kernel switches to NOHZ
migration is enabled, if the user did not disable it via the sysctl
prior to the switch. If nohz=off is on the kernel command line,
migration stays disabled no matter what.
Before:
47.76% hog [.] main
14.84% [kernel] [k] _raw_spin_lock_irqsave
9.55% [kernel] [k] _raw_spin_unlock_irqrestore
6.71% [kernel] [k] mod_timer
6.24% [kernel] [k] lock_timer_base.isra.38
3.76% [kernel] [k] detach_if_pending
3.71% [kernel] [k] del_timer
2.50% [kernel] [k] internal_add_timer
1.51% [kernel] [k] get_nohz_timer_target
1.28% [kernel] [k] __internal_add_timer
0.78% [kernel] [k] timerfn
0.48% [kernel] [k] wake_up_nohz_cpu
After:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.127050787@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Simplify the handling of the flag storage for the timer statistics. No
intermediate storage anymore. Just hand over the flags field.
I left the printout of 'deferrable' for now because changing this
would be an ABI update and I have no idea how strong people feel about
that. OTOH, I wonder whether we should kill the whole timer stats
stuff because all of that information can be retrieved via ftrace/perf
as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.046626248@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Instead of storing a pointer to the per cpu tvec_base we can simply
cache a CPU index in the timer_list and use that to get hold of the
correct per cpu tvec_base. This is only used in lock_timer_base() and
the slightly larger code is peanuts versus the spinlock operation and
the d-cache foot print of the timer wheel.
Aside of that this allows to get rid of following nuisances:
- boot_tvec_base
That statically allocated 4k bss data is just kept around so the
timer has a home when it gets statically initialized. It serves no
other purpose.
With the CPU index we assign the timer to CPU0 at static
initialization time and therefor can avoid the whole boot_tvec_base
dance. That also simplifies the init code, which just can use the
per cpu base.
Before:
text data bss dec hex filename
17491 9201 4160 30852 7884 ../build/kernel/time/timer.o
After:
text data bss dec hex filename
17440 9193 0 26633 6809 ../build/kernel/time/timer.o
- Overloading the base pointer with various flags
The CPU index has enough space to hold the flags (deferrable,
irqsafe) so we can get rid of the extra masking and bit fiddling
with the base pointer.
As a benefit we reduce the size of struct timer_list on 64 bit
machines. 4 - 8 bytes, a size reduction up to 15% per struct timer_list,
which is a real win as we have tons of them embedded in other structs.
This changes also the newly added deferrable printout of the timer
start trace point to capture and print all timer->flags, which allows
us to decode the target cpu of the timer as well.
We might have used bitfields for this, but that would change the
static initializers and the init function for no value to accomodate
big endian bitfields.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Badhri Jagan Sridharan <Badhri@google.com>
Link: http://lkml.kernel.org/r/20150526224511.950084301@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This reduces the size of struct tvec_base by 50% and results in
slightly smaller code as well.
Before:
struct tvec_base: size: 8256, cachelines: 129
text data bss dec hex filename
17698 13297 8256 39251 9953 ../build/kernel/time/timer.o
After:
struct tvec_base: 4160, cachelines: 65
text data bss dec hex filename
17491 9201 4160 30852 7884 ../build/kernel/time/timer.o
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224511.854731214@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The FIFO guarantee is only there if two timers are queued into the
same bucket at the same jiffie on the same cpu:
- The slack value depends on the delta between expiry and enqueue
time, so the resulting expiry time can be different for timers
which are queued in different jiffies.
- Timers which are queued into the secondary array end up after a
later queued timer which was queued into the primary array due to
cascading.
- Timers can end up on different cpus due to the NOHZ target moving
around. Obviously there is no guarantee of expiry ordering between
cpus.
So anything which relies on FIFO behaviour of the timer wheel is
broken already.
This is a preparatory patch for converting the timer wheel to hlist
which reduces the memory foot print of the wheel by 50%.
It's a seperate patch so any (unlikely to happen) regression caused by
this can be identified clearly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Cc: George Spelvin <linux@horizon.com>
Link: http://lkml.kernel.org/r/20150526224511.757520403@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
catchup_timer_jiffies() has been applied blindly to several functions
without looking for possible better ways to do it.
1) internal_add_timer()
Move the update to base->all_timers before we actually insert the
timer into the wheel.
2) detach_if_pending()
Again the update to base->all_timers allows us to explicitely do
the timer_jiffies update in place, if this was the last timer which
got removed.
3) __run_timers()
We only check on entry, which is silly, because base->timer_jiffies
can be behind - especially on NOHZ kernels - and if there is a
single deferrable timer somewhere between base->timer_jiffies and
jiffies we expire it and then loop until base->timer_jiffies ==
jiffies.
Move it into the loop.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224511.662994644@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* pm-sleep:
PM / sleep: trace_device_pm_callback coverage in dpm_prepare/complete
PM / wakeup: add a dummy wakeup_source to record statistics
PM / sleep: Make suspend-to-idle-specific code depend on CONFIG_SUSPEND
PM / sleep: Return -EBUSY from suspend_enter() on wakeup detection
PM / tick: Add tracepoints for suspend-to-idle diagnostics
PM / sleep: Fix symbol name in a comment in kernel/power/main.c
leds / PM: fix hibernation on arm when gpio-led used with CPU led trigger
ARM: omap-device: use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
bus: omap_l3_noc: add missed callbacks for suspend-to-disk
PM / sleep: Add macro to define common noirq system PM callbacks
PM / sleep: Refine diagnostic messages in enter_state()
PM / wakeup: validate wakeup source before activating it.
* pm-runtime:
PM / Runtime: Update last_busy in rpm_resume
PM / runtime: add note about re-calling in during device probe()
Currently an hrtimer callback function cannot free its own timer
because __run_hrtimer() still needs to clear HRTIMER_STATE_CALLBACK
after it. Freeing the timer would result in a clear use-after-free.
Solve this by using a scheme similar to regular timers; track the
current running timer in hrtimer_clock_base::running.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: wanpeng.li@linux.intel.com
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.471563047@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The fix in d151832650 (time: Move clock_was_set_seq update
before updating shadow-timekeeper) was unfortunately incomplete.
The main gist of that change was to do the shadow-copy update
last, so that any state changes were properly duplicated, and
we wouldn't accidentally have stale data in the shadow.
Unfortunately in the main update_wall_time() logic, we update
use the shadow-timekeeper to calculate the next update values,
then while holding the lock, copy the shadow-timekeeper over,
then call timekeeping_update() to do some additional
bookkeeping, (skipping the shadow mirror). The bug with this is
the additional bookkeeping isn't all read-only, and some
changes timkeeper state. Thus we might then overwrite this state
change on the next update.
To avoid this problem, do the timekeeping_update() on the
shadow-timekeeper prior to copying the full state over to
the real-timekeeper.
This avoids problems with both the clock_was_set_seq and
next_leap_ktime being overwritten and possibly the
fast-timekeepers as well.
Many thanks to Prarit for his rigorous testing, which discovered
this problem, along with Prarit and Daniel's work validating this
fix.
Reported-by: Prarit Bhargava <prarit@redhat.com>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434560753-7441-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
CLOCK_EVT_MODE_* macros are present for backward compatibility (as most
of the drivers are still using old ->set_mode() interface).
These macro's shouldn't be used anymore in code, that is common to both
driver interfaces, i.e. ->set_mode() and ->set_state_*().
Drivers implementing ->set_state_*() interface, which have their
clkevt->mode set to 0 (clkevt device structures are normally globally
defined), will not participate in suspend/resume as they will always be
marked as UNUSED.
Fix this by checking state of the clockevent device instead of mode,
which is updated for both the interfaces.
Fixes: ac34ad27fc ("clockevents: Do not suspend/resume if unused")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: alexandre.belloni@free-electrons.com
Cc: sylvain.rochet@finsecur.com
Link: http://lkml.kernel.org/r/a1964eef6e8a47d02b1ff9083c6c91f73f0ff643.1434537215.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since the leapsecond is applied at tick-time, this means there is a
small window of time at the start of a leap-second where we cross into
the next second before applying the leap.
This patch modified adjtimex so that the leap-second is applied on the
second edge. Providing more correct leapsecond behavior.
This does make it so that adjtimex()'s returned time values can be
inconsistent with time values read from gettimeofday() or
clock_gettime(CLOCK_REALTIME,...) for a brief period of one tick at
the leapsecond. However, those other interfaces do not provide the
TIME_OOP time_state return that adjtimex() provides, which allows the
leapsecond to be properly represented. They instead only see a time
discontinuity, and cannot tell the first 23:59:59 from the repeated
23:59:59 leap second.
This seems like a reasonable tradeoff given clock_gettime() /
gettimeofday() cannot properly represent a leapsecond, and users
likely care more about performance, while folks who are using
adjtimex() more likely care about leap-second correctness.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently, leapsecond adjustments are done at tick time. As a result,
the leapsecond was applied at the first timer tick *after* the
leapsecond (~1-10ms late depending on HZ), rather then exactly on the
second edge.
This was in part historical from back when we were always tick based,
but correcting this since has been avoided since it adds extra
conditional checks in the gettime fastpath, which has performance
overhead.
However, it was recently pointed out that ABS_TIME CLOCK_REALTIME
timers set for right after the leapsecond could fire a second early,
since some timers may be expired before we trigger the timekeeping
timer, which then applies the leapsecond.
This isn't quite as bad as it sounds, since behaviorally it is similar
to what is possible w/ ntpd made leapsecond adjustments done w/o using
the kernel discipline. Where due to latencies, timers may fire just
prior to the settimeofday call. (Also, one should note that all
applications using CLOCK_REALTIME timers should always be careful,
since they are prone to quirks from settimeofday() disturbances.)
However, the purpose of having the kernel do the leap adjustment is to
avoid such latencies, so I think this is worth fixing.
So in order to properly keep those timers from firing a second early,
this patch modifies the ntp and timekeeping logic so that we keep
enough state so that the update_base_offsets_now accessor, which
provides the hrtimer core the current time, can check and apply the
leapsecond adjustment on the second edge. This prevents the hrtimer
core from expiring timers too early.
This patch does not modify any other time read path, so no additional
overhead is incurred. However, this also means that the leap-second
continues to be applied at tick time for all other read-paths.
Apologies to Richard Cochran, who pushed for similar changes years
ago, which I resisted due to the concerns about the performance
overhead.
While I suspect this isn't extremely critical, folks who care about
strict leap-second correctness will likely want to watch
this. Potentially a -stable candidate eventually.
Originally-suggested-by: Richard Cochran <richardcochran@gmail.com>
Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Reported-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently the leapsecond logic uses what looks like magic values.
Improve this by defining SECS_PER_DAY and using that macro
to make the logic more clear.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
It was reported that 868a3e915f (hrtimer: Make offset
update smarter) was causing timer problems after suspend/resume.
The problem with that change is the modification to
clock_was_set_seq in timekeeping_update is done prior to
mirroring the time state to the shadow-timekeeper. Thus the
next time we do update_wall_time() the updated sequence is
overwritten by whats in the shadow copy.
This patch moves the shadow-timekeeper mirroring to the end
of the function, after all updates have been made, so all data
is kept in sync.
(This patch also affects the update_fast_timekeeper calls which
were also problematically done prior to the mirroring).
Reported-and-tested-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1434063297-28657-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
clocksource messages aren't prefixed in dmesg so it's a bit unclear
what subsystem emits the messages.
Use pr_fmt and pr_<level> to auto-prefix the messages appropriately.
Miscellanea:
o Remove "Warning" from KERN_WARNING level messages
o Align "timekeeping watchdog: " messages
o Coalesce formats
o Align multiline arguments
Signed-off-by: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1432579795.2846.75.camel@perches.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor the usecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability. This is analogous to the msecs_to_jiffies()
cleanup in commit ca42aaf0c8 ("time: Refactor msecs_to_jiffies")
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1432832996-12129-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The only sensible way to make abuse of core internal fields obvious
and easy to grep for.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
We want to rename dev->state, so provide proper get and set
functions. Rename clockevents_set_state() to
clockevents_switch_state() to avoid confusion.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Because with latches there is a strict data dependency on the seq load
we can avoid the rmb in favour of a read_barrier_depends.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Improve the documentation of the latch technique as used in the
current timekeeping code, such that it can be readily employed
elsewhere.
Borrow from the comments in timekeeping and replace those with a
reference to this more generic comment.
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
There is no point in calling suspend/resume for unused clockevents as
they are already stopped and disabled.
This is really important for AT91 as the hardware is a trainwreck and
takes ages to synchronize.
Reported-by: Sylvain Rochet <sylvain.rochet@finsecur.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1421399151-26800-1-git-send-email-alexandre.belloni@free-electrons.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that we have a read_boot_clock64() function available on every
architecture, and converted all the users to it, it's time to remove
the (now unused) read_boot_clock() completely from the kernel.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
[jstultz: Minor commit message tweak suggested by Ingo]
Signed-off-by: John Stultz <john.stultz@linaro.org>
The timer_start event now shows whether the timer is
deferrable in case of a low-res timer. The debug_activate
function now includes a deferrable flag while calling
the trace_timer_start event.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
[jstultz: Fixed minor whitespace and grammer tweaks
pointed out by Ingo]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Ingo suggested that the timekeeping debugging variables
recently added should not be global, and should be tied
to the timekeeper's read_base.
Thus this patch implements that suggestion.
This version is different from the earlier versions
as it keeps the variables in the timekeeper structure
rather then in the tkr.
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This patch series introduces a new function
u32 ktime_get_resolution_ns(void)
which allows to clean up some driver code.
In particular the IIO subsystem has a function to provide timestamps for
events but no means to get their resolution. So currently the dht11 driver
tries to guess the resolution in a rather messy and convoluted way. We
can do much better with the new code.
This API is not designed to be exposed to user space.
This has been tested on i386, sunxi and mxs.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Harald Geyer <harald@ccbib.org>
[jstultz: Tweaked to make it build after upstream changes]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Invalid values may overflow later, leading to undefined behaviour when
multiplied by 60 to get the amount of seconds.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
To avoid getting spurious interrupts on a tickless CPU, clockevent
device can now be stopped by switching to ONESHOT_STOPPED state.
The natural place for handling this transition is tick_program_event().
On 'expires == KTIME_MAX', we skip programming the event and so we need
to fix such call sites as well, to always call tick_program_event()
irrespective of the expires value.
Once the clockevent device is required again, check if it was earlier
put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT
before programming its event.
To make sure we haven't missed any corner case, add a WARN() for the
case where we try to reprogram clockevent device while we aren't
configured in ONESHOT_STOPPED state.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5146b07be7f0bc497e0ebae036590ec2fa73e540.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When no timers/hrtimers are pending, the expiry time is set to a
special value: 'KTIME_MAX'. This normally happens with
NO_HZ_{IDLE|FULL} in both LOWRES/HIGHRES modes.
When 'expiry == KTIME_MAX', we either cancel the 'tick-sched' hrtimer
(NOHZ_MODE_HIGHRES) or skip reprogramming clockevent device
(NOHZ_MODE_LOWRES). But, the clockevent device is already
reprogrammed from the tick-handler for next tick.
As the clock event device is programmed in ONESHOT mode it will at
least fire one more time (unnecessarily). Timers on few
implementations (like arm_arch_timer, etc.) only support PERIODIC mode
and their drivers emulate ONESHOT over that. Which means that on these
platforms we will get spurious interrupts periodically (at last
programmed interval rate, normally tick rate).
In order to avoid spurious interrupts, the clockevent device should be
stopped or its interrupts should be masked.
A simple (yet hacky) solution to get this fixed could be: update
hrtimer_force_reprogram() to always reprogram clockevent device and
update clockevent drivers to STOP generating events (or delay it to
max time) when 'expires' is set to KTIME_MAX. But the drawback here is
that every clockevent driver has to be hacked for this particular case
and its very easy for new ones to miss this.
However, Thomas suggested to add an optional state ONESHOT_STOPPED to
solve this problem: lkml.org/lkml/2014/5/9/508.
This patch adds support for ONESHOT_STOPPED state in clockevents
core. It will only be available to drivers that implement the
state-specific callbacks instead of the legacy ->set_mode() callback.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/b8b383a03ac07b13312c16850b5106b82e4245b5.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor the msecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability.
[ tglx: Verified that there is no binary code change ]
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-2-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kernel/time/timeconst.h is moved to include/generated/ and generated
by the top level Kbuild. This allows using timeconst.h in an earlier
build stage.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since idle_should_freeze() is defined to always return 'false'
for CONFIG_SUSPEND unset, all of the code depending on it in
cpuidle_idle_call() is not necessary in that case.
Make that code depend on CONFIG_SUSPEND too to avoid building it
when it is not going to be used.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Add suspend/resume tracepoints to tick_freeze() and tick_unfreeze()
to catch when timekeeping is suspended and resumed during suspend-to-idle
so as to be able to check whether or not we enter the "frozen" state
and to measure the time spent in it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
It was noted that the 32bit implementation of ktime_divns()
was doing unsigned division and didn't properly handle
negative values.
And when a ktime helper was changed to utilize
ktime_divns, it caused a regression on some IR blasters.
See the following bugzilla for details:
https://bugzilla.redhat.com/show_bug.cgi?id=1200353
This patch fixes the problem in ktime_divns by checking
and preserving the sign bit, and then reapplying it if
appropriate after the division, it also changes the return
type to a s64 to make it more obvious this is expected.
Nicolas also pointed out that negative dividers would
cause infinite loops on 32bit systems, negative dividers
is unlikely for users of this function, but out of caution
this patch adds checks for negative dividers for both
32-bit (BUG_ON) and 64-bit(WARN_ON) versions to make sure
no such use cases creep in.
[ tglx: Hand an u64 to do_div() to avoid the compiler warning ]
Fixes: 166afb6451 'ktime: Sanitize ktime_to_us/ms conversion'
Reported-and-tested-by: Trevor Cordes <trevor@tecnopolis.ca>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1431118043-23452-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull timer fix from Thomas Gleixner:
"A simple fix to actually shut down a detached device instead of
keeping it active"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clockevents: Shutdown detached clockevent device
Recent optimizations were made to thread_group_cputimer to improve its
scalability by keeping track of cputime stats without a lock. However,
the values were open coded to the structure, causing them to be at
a different abstraction level from the regular task_cputime structure.
Furthermore, any subsequent similar optimizations would not be able to
share the new code, since they are specific to thread_group_cputimer.
This patch adds the new task_cputime_atomic data structure (introduced in
the previous patch in the series) to thread_group_cputimer for keeping
track of the cputime atomically, which also helps generalize the code.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1430251224-5764-6-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While running a database workload, we found a scalability issue with itimers.
Much of the problem was caused by the thread_group_cputimer spinlock.
Each time we account for group system/user time, we need to obtain a
thread_group_cputimer's spinlock to update the timers. On larger systems
(such as a 16 socket machine), this caused more than 30% of total time
spent trying to obtain this kernel lock to update these group timer stats.
This patch converts the timers to 64-bit atomic variables and use
atomic add to update them without a lock. With this patch, the percent
of total time spent updating thread group cputimer timers was reduced
from 30% down to less than 1%.
Note: On 32-bit systems using the generic 64-bit atomics, this causes
sample_group_cputimer() to take locks 3 times instead of just 1 time.
However, we tested this patch on a 32-bit system ARM system using the
generic atomics and did not find the overhead to be much of an issue.
An explanation for why this isn't an issue is that 32-bit systems usually
have small numbers of CPUs, and cacheline contention from extra spinlocks
called periodically is not really apparent on smaller systems.
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1430251224-5764-4-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
ACCESS_ONCE doesn't work reliably on non-scalar types. This patch removes
the rest of the existing usages of ACCESS_ONCE() in the scheduler, and use
the new READ_ONCE() and WRITE_ONCE() APIs as appropriate.
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Waiman Long <Waiman.Long@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1430251224-5764-2-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Simon Horman reported this crash on a system with
high-res timers disabled but nohz enabled:
> ------------[ cut here ]------------
> kernel BUG at kernel/irq_work.c:135!
BUG_ON(!irqs_disabled());
So something enabled interrupts in the periodic tick handling machinery,
and that code path indeed has a local_irq_disable()/enable pair in
tick_nohz_switch_to_nohz() which causes havoc. Fix it.
This patch also fixes a +nohz -hrtimers hang reported by Ingo Molnar.
Reported-by: Simon Horman <horms@verge.net.au>
Reported-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505071425520.4225@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The hrtimer callback in the hrtimer's tick broadcast code sometimes
incorrectly ends up scheduling events at the current tick causing the
kernel to hang servicing the same hrtimer forever. This typically
happens when a device is swapped out by
tick_install_broadcast_device(), which replaces the event handler with
clock_events_handle_noop() and sets the device mode to
CLOCK_EVT_MODE_UNUSED. If the timer is scheduled when this happens,
the next_event field will not be updated and the hrtimer ends up being
restarted at the current tick. To prevent this from happening, only
try to restart the hrtimer if the broadcast clock event device is in
one of the active modes and try to cancel the timer when entering the
CLOCK_EVT_MODE_UNUSED mode.
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1429880765-5558-1-git-send-email-andreas.sandberg@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Today the number of bits of the broadcast masks that is output into
/proc/timer_list is sizeof(unsigned long). This means that on machines
with a larger number of CPUs, the bitmasks of CPUs beyond this range do
not appear.
Fix this by using bitmap printing through "%*pb" instead, so as to
output the broadcast masks for the range of nr_cpu_ids into
/proc/timer_list.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: peterz@infradead.org
Cc: linuxppc-dev@ozlabs.org
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/20150428084520.3314.62668.stgit@preeti.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Simplify the oneshot logic by avoiding the reprogramming loops. That
also allows to call the cpu local handler outside of the
broadcast_lock held region.
Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With the removal of the hrtimer softirq the switch to highres/nohz
mode happens in the tick interrupt. That leads to a livelock when the
per cpu event handler is directly called from the broadcast handler
under broadcast lock because broadcast lock needs to be taken for the
highres/nohz switch as well.
Solve this by calling the cpu local handler outside the broadcast_lock
held region.
Fixes: c6eb3f70d4 "hrtimer: Get rid of hrtimer softirq"
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
A clockevent device is marked DETACHED when it is replaced by another
clockevent device.
The device is shutdown properly for drivers that implement legacy
->set_mode() callback, as we call ->set_mode() for CLOCK_EVT_MODE_UNUSED
as well.
But for the new per-state callback interface, we skip shutting down the
device, as we thought its an internal state change. That wasn't correct.
The effect is that the device is left programmed in oneshot or periodic
mode.
Fall-back to 'case CLOCK_EVT_STATE_SHUTDOWN', to shutdown the device.
Fixes: bd624d75db "clockevents: Introduce mode specific callbacks"
Reported-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/eef0a91c51b74d4e52c8e5a95eca27b5a0563f07.1428650683.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Because we drop cpu_base->lock around calling hrtimer::function, it is
possible for hrtimer_start() to come in between and enqueue the timer.
If hrtimer::function then returns HRTIMER_RESTART we'll hit the BUG_ON
because HRTIMER_STATE_ENQUEUED will be set.
Since the above is a perfectly valid scenario, remove the BUG_ON and
make the enqueue_hrtimer() call conditional on the timer not being
enqueued already.
NOTE: in that concurrent scenario its entirely common for both sites
to want to modify the hrtimer, since hrtimers don't provide
serialization themselves be sure to provide some such that the
hrtimer::function and the hrtimer_start() caller don't both try and
fudge the expiration state at the same time.
To that effect, add a WARN when someone tries to forward an already
enqueued timer, the most common way to change the expiry of self
restarting timers. Ideally we'd put the WARN in everything modifying
the expiry but most of that is inlines and we don't need the bloat.
Fixes: 2d44ae4d71 ("hrtimer: clean up cpu->base locking tricks")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20150415113105.GT5029@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
do_usleep_range() and schedule_hrtimeout_range() are __sched as
well. So it makes no sense to have the exported function in a
different section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.833709502@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The only user ignores it anyway and rightfully so.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.756060258@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We can do a lockless check for hrtimer_active before actually taking
the lock in hrtimer[_try_to]_cancel. This is useful for hotpath users
like nanosleep as they avoid the lock dance when the timer has
expired.
This is safe because active is true when the timer is enqueued or the
callback is running. Taking the hrtimer base lock does not protect
against concurrent hrtimer_start calls, the callsite has to do the
proper serialization itself.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.580273114@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
No user was ever interested whether the timer was active or not when
it was started. All abusers of the return value are gone, so get rid
of it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.483556394@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The assignment of bc_moved in the conditional construct relies on the
fact that in the case of hrtimer_start() invocation the return value
is always 0. It took me a while to understand it.
We want to get rid of the hrtimer_start() return value. Open code the
logic which makes it readable as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.404751457@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We want to get rid of the hrtimer_start() return value and the alarm
timer return value is nowhere used. Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20150414203503.243910615@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The check for hrtimer_active() after starting the timer is
pointless. If the timer is inactive it has expired already and
therefor the task pointer is already NULL.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203502.907149271@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
No point for an extra export just to set the extra argument of
hrtimer_start_range_ns() to 0.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203502.808544539@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The evaluation of the next timer in the nohz code is based on jiffies
while all the tick internals are nano seconds based. We have also to
convert hrtimer nanoseconds to jiffies in the !highres case. That's
just wrong and introduces interesting corner cases.
Turn it around and convert the next timer wheel timer expiry and the
rcu event to clock monotonic and base all calculations on
nanoseconds. That identifies the case where no timer is pending
clearly with an absolute expiry value of KTIME_MAX.
Makes the code more readable and gets rid of the jiffies magic in the
nohz code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.184198593@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Get rid of one indentation level. Preparatory patch for a major
rework. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.101563235@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We already got rid of the hrtimer reprogramming loops and hoops as
hrtimer now enforces an interrupt if the enqueued time is in the past.
Do the same for the nohz non highres mode. That gets rid of the need
to raise the softirq which only serves the purpose of getting the
machine out of the inner idle loop.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.023464878@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hrtimer_start() enforces a timer interrupt if the timer is already
expired. Get rid of the checks and the forward loop.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203501.943658239@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hrtimer softirq is a leftover from the initial implementation and
serves only the purpose to handle the enqueueing of already expired
timers in the high resolution timer mode. We discussed whether we
change the return value and force all start sites to handle that the
timer is already expired, but that would be a Herculean task and I'm
not sure whether its a good idea to enforce that handling on
everyone.
A simpler solution is to enforce a timer interrupt instead of raising
and scheduling a softirq. Just use the existing infrastructure to do
so and remove all the softirq leftovers.
The HRTIMER softirq enum is now unused, but kept around because trace
parsers rely on the existing numbering.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.840834708@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
__remove_hrtimer() needs to evaluate the expiry time to figure out
whether the timer which is removed is eventually the first expiring
timer on the cpu. Keep a pointer to it, which is lazily updated, so we
can avoid the evaluation dance and retrieve the information from there.
Generates slightly better code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.752838019@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Use the return value instead of reevaluating the information.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.658152945@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The active_bases field is guaranteed to be in sync with the timerqueue
of the corresponding clock base. So we can use it for iterating over
the clock bases. This allows to break out early if no more active
clock bases are available and avoids touching the cache lines of
inactive clock bases.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.322887675@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
On every tick/hrtimer interrupt we update the offset variables of the
clock bases. That's silly because these offsets change very seldom.
Add a sequence counter to the time keeping code which keeps track of
the offset updates (clock_was_set()). Have a sequence cache in the
hrtimer cpu bases to evaluate whether the offsets must be updated or
not. This allows us later to avoid pointless cacheline pollution.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20150414203501.132820245@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
The softirq time field in the clock bases is an optimization from the
early days of hrtimers. It provides a coarse "jiffies" like time
mostly for self rearming timers.
But that comes with a price:
- Larger code size
- Extra storage space
- Duplicated functions with really small differences
The benefit of this is optimization is marginal for contemporary
systems.
Consolidate everything on the high resolution timer
implementation. This makes further optimizations possible.
Text size reduction:
x8664 -95, i386 -356, ARM -148, ARM64 -40, power64 -16
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.039977424@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
No point in having usigned long for /proc/timer_list statistics. Make
them unsigned int.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.959773467@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The resolution is directly accessible now. So its simpler just to fill
in the values of the timespec and be done with it.
Text size reduction (combined with "hrtimer: Get rid of the resolution
field in hrtimer_clock_base"):
x8664 -61, i386 -221, ARM -60, power64 -48
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.879888080@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The field has no value because all clock bases have the same
resolution. The resolution only changes when we switch to high
resolution timer mode. We can evaluate that from a single static
variable as well. In the !HIGHRES case its simply a constant.
Export the variable, so we can simplify the usage sites.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
'active_bases' indicates which clock-base have active timer. The
intention of this bit field was to avoid evaluating inactive bases. It
was introduced with the introduction of the BOOTTIME and TAI clock
bases, but it was never brought into full use.
We want to use it now, but in __remove_hrtimer() the update happens
after the calling hrtimer_force_reprogram() which has to evaluate all
clock bases for the next expiring timer. So in case the last timer of
a clock base got removed we still see the active bit and therefor
evaluate the clock base for no value. There are further optimizations
possible when active_bases is updated in the right place.
Move the update before the call to hrtimer_force_reprogram()
[ tglx: Massaged changelog ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/20150414203500.533438642@linutronix.de
Link: http://lkml.kernel.org/r/c7c8ebcd9ed88bb09d76059c745a1fafb48314e7.1428039899.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Document the calling context conditions.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150413210035.178751779@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
commit 61edec81d2 "timekeeping: Simplify timekeeping_clocktai()"
implemented timekeeping_clocktai() as an inline function, but left the
old extern prototype in the header file. Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This macro can be converted to a static function to reduce
object size.
(x86-64 defconfig)
$ size kernel/time/timer_list.o*
text data bss dec hex filename
6583 8 0 6591 19bf kernel/time/timer_list.o.old
4647 8 0 4655 122f kernel/time/timer_list.o.new
Signed-off-by: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1429295958.2850.104.camel@perches.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Here's the big char/misc driver patchset for 4.1-rc1.
Lots of different driver subsystem updates here, nothing major, full
details are in the shortlog below.
All of this has been in linux-next for a while.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here's the big char/misc driver patchset for 4.1-rc1.
Lots of different driver subsystem updates here, nothing major, full
details are in the shortlog.
All of this has been in linux-next for a while"
* tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits)
mei: trace: remove unused TRACE_SYSTEM_STRING
DTS: ARM: OMAP3-N900: Add lis3lv02d support
Documentation: DT: lis302: update wakeup binding
lis3lv02d: DT: add wakeup unit 2 and wakeup threshold
lis3lv02d: DT: use s32 to support negative values
Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case
Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case
mei: replace check for connection instead of transitioning
mei: use mei_cl_is_connected consistently
mei: fix mei_poll operation
hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()
Drivers: hv: hv_balloon: survive ballooning request with num_pages=0
Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function
Drivers: hv: hv_balloon: do not online pages in offline blocks
hv: remove the per-channel workqueue
hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind()
hv: run non-blocking message handlers in the dispatch tasklet
coresight: moving to new "hwtracing" directory
coresight-tmc: Adding a status interface to sysfs
coresight: remove the unnecessary configuration coresight-default-sink
...
Arch specific management of xtime/jiffies/wall_to_monotonic is
gone for quite a while. Zap the stale comment.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/2422730.dmO29q661S@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.
Split out the cleanup function for a dead cpu and invoke it
directly from the cpu down code. Make it conditional on
CPU_HOTPLUG as well.
Temporary change, will be refined in the future.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased, added clockevents_notify() removal ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1735025.raBZdQHM3m@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.
Split out the tick_handover call and invoke it explicitely from
the hotplug code. Temporary solution will be cleaned up in later
patches.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebase ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1658173.RkEEILFiQZ@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that all users are converted over to explicit calls into the
clockevents state machine, remove the notification chain leftovers.
Original-from: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/14018863.NQUzkFuafr@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.
Split out the broadcast oneshot control into a separate function
and provide inline helpers. Switch clockevents_notify() over.
This will go away once all callers are converted.
This also gets rid of the nested locking of clockevents_lock and
broadcast_lock. The broadcast oneshot control functions do not
require clockevents_lock. Only the managing functions
(setup/shutdown/suspend/resume of the broadcast device require
clockevents_lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/13000649.8qZuEDV0OA@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All users converted. Remove the notify leftovers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/2076318.76XJZ8QYP3@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.
Split out the broadcast control into a separate function and
provide inline helpers. Switch clockevents_notify() over. This
will go away once all callers are converted.
This also gets rid of the nested locking of clockevents_lock and
broadcast_lock. The broadcast control functions do not require
clockevents_lock. Only the managing functions
(setup/shutdown/suspend/resume of the broadcast device require
clockevents_lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/8086559.ttsuS0n1Xr@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ingo noted that the description of clocks_calc_max_nsecs()'s
50% safety margin was somewhat circular. So this patch tries
to improve the comment to better explain what we mean by the
50% safety margin and why we need it.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-20-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If a system does not provide a persistent_clock(), the time
will be updated on resume by rtc_resume(). With the addition
of the non-stop clocksources for suspend timing, those systems
set the time on resume in timekeeping_resume(), but may not
provide a valid persistent_clock().
This results in the rtc_resume() logic thinking no one has set
the time and it then will over-write the suspend time again,
which is not necessary and only increases clock error.
So, fix this for rtc_resume().
This patch also improves the name of persistent_clock_exist to
make it more grammatical.
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-19-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When there's no persistent clock, normally
timekeeping_suspend_time should always be zero, but this can
break in timekeeping_suspend().
At T1, there was a system suspend, so old_delta was assigned T1.
After some time, one time adjustment happened, and xtime got the
value of T1-dt(0s<dt<2s). Then, there comes another system
suspend soon after this adjustment, obviously we will get a
small negative delta_delta, resulting in a negative
timekeeping_suspend_time.
This is problematic, when doing timekeeping_resume() if there is
no nonstop clocksource for example, it will hit the else leg and
inject the improper sleeptime which is the wrong logic.
So, we can solve this problem by only doing delta related code
when the persistent clock is existent. Actually the code only
makes sense for persistent clock cases.
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-18-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
timekeeping_inject_sleeptime64() is only used by RTC
suspend/resume, so add build dependencies on the necessary RTC
related macros.
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
[ Improve commit message clarity. ]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-16-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As part of addressing in-kernel y2038 issues, this patch adds
update_persistent_clock64() and replaces all the call sites of
update_persistent_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
update_persistent_clock().
This allows architecture specific implementations to be
converted independently, and eventually y2038-unsafe
update_persistent_clock() can be removed after all its
architecture specific implementations have been converted to
update_persistent_clock64().
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As part of addressing in-kernel y2038 issues, this patch adds
read_persistent_clock64() and replaces all the call sites of
read_persistent_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
read_persistent_clock().
This allows architecture specific implementations to be
converted independently, and eventually the y2038 unsafe
read_persistent_clock() can be removed after all its
architecture specific implementations have been converted to
read_persistent_clock64().
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As part of addressing in-kernel y2038 issues, this patch adds
read_boot_clock64() and replaces all the call sites of
read_boot_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
read_boot_clock().
This allows architecture specific implementations to be
converted independently, and eventually the y2038 unsafe
read_boot_clock() can be removed after all its architecture
specific implementations have been converted to
read_boot_clock64().
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove one CONFIG_HOTPLUG_CPU #ifdef in trade for introducing one
CONFIG_SMP #ifdef.
The CONFIG_SMP ifdef avoids declaring the per-CPU __tvec_bases storage
on UP systems since they already have boot_tvec_bases.
Also (re)add a runtime check on the base alignment -- for the paranoid
amongst us :-)
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/fdd2d35e169bdc554ffa3fe77f77716298c75ada.1427814611.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no need to call init_timers_cpu() on every CPU hotplug event,
there is not much we need to reset.
- Timer-lists are already empty at the end of migrate_timers().
- timer_jiffies will be refreshed while adding a new timer, after the
CPU is online again.
- active_timers and all_timers can be reset from migrate_timers().
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/54a1c30ea7b805af55beb220cadf5a07a21b0a4d.1427814611.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Memory for the 'tvec_base' array is allocated separately for the boot CPU (statically)
and non-boot CPUs (dynamically).
The reason is because __TIMER_INITIALIZER() needs to set ->base to a
valid pointer (because we've made NULL special, hint: lock_timer_base())
and we cannot get a compile time pointer to per-cpu entries because we
don't know where we'll map the section, even for the boot cpu.
This can be simplified a bit by statically allocating per-cpu memory.
The only disadvantage is that memory for one of the structures will stay
unused, i.e. for the boot CPU, which uses boot_tvec_bases.
This will also guarantee that tvec_base is cacheline aligned. Even
though tvec_base has ____cacheline_aligned stuck on, kzalloc_node() does
not actually respect that (but guarantees a minimum u64 alignment).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/17cdf560f2727f687ab159707d0aa591f8a2f82d.1427814611.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was found when doing a hotplug stress test on POWER, that the
machine either hit softlockups or rcu_sched stall warnings. The
issue was traced to commit:
7cba160ad7 ("powernv/cpuidle: Redesign idle states management")
which exposed the cpu_down() race with hrtimer based broadcast mode:
5d1638acb9 ("tick: Introduce hrtimer based broadcast")
The race is the following:
Assume CPU1 is the CPU which holds the hrtimer broadcasting duty
before it is taken down.
CPU0 CPU1
cpu_down() take_cpu_down()
disable_interrupts()
cpu_die()
while (CPU1 != CPU_DEAD) {
msleep(100);
switch_to_idle();
stop_cpu_timer();
schedule_broadcast();
}
tick_cleanup_cpu_dead()
take_over_broadcast()
So after CPU1 disabled interrupts it cannot handle the broadcast
hrtimer anymore, so CPU0 will be stuck forever.
Fix this by explicitly taking over broadcast duty before cpu_die().
This is a temporary workaround. What we really want is a callback
in the clockevent device which allows us to do that from the dying
CPU by pushing the hrtimer onto a different cpu. That might involve
an IPI and is definitely more complex than this immediate fix.
Changelog was picked up from:
https://lkml.org/lkml/2015/2/16/213
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: nicolas.pitre@linaro.org
Cc: peterz@infradead.org
Cc: rjw@rjwysocki.net
Fixes: http://linuxppc.10917.n7.nabble.com/offlining-cpus-breakage-td88619.html
Link: http://lkml.kernel.org/r/20150330092410.24979.59887.stgit@preeti.in.ibm.com
[ Merged it to the latest timer tree, renamed the callback, tidied up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move the broadcasting related section to the GENERIC_CLOCKEVENTS=y
section - this also solves build failures on architectures that
don't use generic clockevents yet.
Also standardize include file style to make it easier to read, and
use nesting depth aware preprocessor directives to make future merges
easier.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use the new tick_suspend/resume_local() and get rid of the
homebrewn implementation of these in the ARM bL switcher. The
check for the cpumask is completely pointless. There is no harm
to suspend a per cpu tick device unconditionally. If that's a
real issue then we fix it proper at the core level and not with
some completely undocumented hacks in some random core code.
Move the tick internals to the core code, now that this nuisance
is gone.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Rebase, changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/1655112.Ws17YsMfN7@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Xen calls on every cpu into tick_resume() which is just wrong.
tick_resume() is for the syscore global suspend/resume
invocation. What XEN really wants is a per cpu local resume
function.
Provide a tick_resume_local() function and use it in XEN.
Also provide a complementary tick_suspend_local() and modify
tick_unfreeze() and tick_freeze(), respectively, to use the
new local tick resume/suspend functions.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Combined two patches, rebased, modified subject/changelog. ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1698741.eezk9tnXtG@vostro.rjw.lan
[ Merged to latest timers/core. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Solely used in tick-broadcast.c and the return value is
hardcoded 0. Make it static and void.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1689058.QkHYDJSRKu@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call.
We are way better off to have explicit calls instead of this
monstrosity. Split out the suspend/resume() calls and invoke
them directly from the call sites.
No locking required at this point because these calls happen
with interrupts disabled and a single cpu online.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased on top of 4.0-rc5. ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/713674030.jVm1qaHuPf@vostro.rjw.lan
[ Rebased on top of latest timers/core. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Called with 'clockevents_lock' held and interrupts disabled
already.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/51005827.yXt5tjZMBs@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
No point to expose everything to the world. People just believe
such functions can be abused for whatever purposes. Sigh.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased on top of 4.0-rc5 ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/28017337.VbCUc39Gme@vostro.rjw.lan
[ Merged to latest timers/core ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
tick-internal.h is pretty confusing as a lot of the stub inlines
are there several times.
Distangle the maze and make clear functional sections.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/16068264.vcNp79HLaT@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move clocksource related stuff to timekeeping.h and remove the
pointless include from ntp.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/2714218.nM5AEfAHj0@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This option was for simpler migration to the clock events code.
Most architectures have been converted and the option has been
disfunctional as a standalone option for quite some time. Remove
it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5021859.jl9OC1medj@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was a requirement in the legacy interface that drivers must
initialize ->mode field to 'CLOCK_EVT_MODE_UNUSED'. This field
isn't used anymore by the new interface and so should be only
checked for the legacy interface.
Probably it can be dropped as well as core doesn't rely on it
anymore, but lets keep it to support legacy interface.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/c6604fa1a77fe1fc8dcab87769857228fb1dadd5.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'enum clock_event_mode' is used for two purposes today:
- to pass mode to the driver of clockevent device::set_mode().
- for managing state of the device for clockevents core.
For supporting new modes/states we have moved away from the
legacy set_mode() callback to new per-mode/state callbacks. New
modes/states shouldn't be exposed to the legacy (now OBSOLOTE)
callbacks and so we shouldn't add new states to 'enum
clock_event_mode'.
Lets have separate enums for the two use cases mentioned above.
Keep using the earlier enum for legacy set_mode() callback and
mark it OBSOLETE. And add another enum to clearly specify the
possible states of a clockevent device.
This also renames the newly added per-mode callbacks to reflect
state changes.
We haven't got rid of 'mode' member of 'struct
clock_event_device' as it is used by some of the clockevent
drivers and it would automatically die down once we migrate
those drivers to the new interface. It ('mode') is only updated
now for the drivers using the legacy interface.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/b6b0143a8a57bd58352ad35e08c25424c879c0cb.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Upcoming patch will redefine possible states of a clockevent
device. The RESUME mode is a special case only for tick's
clockevent devices. In future it can be replaced by ->resume()
callback already available for clockevent devices.
Lets handle it separately so that clockevents_set_mode() only
handles states valid across all devices. This also renames
set_mode_resume() to tick_resume() to make it more explicit.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/c1b0112410870f49e7bf06958e1483eac6c15e20.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for more tk_fast instances, remove all hard-coded
tk_fast_mono references.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150319093400.484279927@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Introduce tkr_raw and make use of it.
base_raw -> tkr_raw.base
clock->{mult,shift} -> tkr_raw.{mult.shift}
Kill timekeeping_get_ns_raw() in favour of
timekeeping_get_ns(&tkr_raw), this removes all mono_raw special
casing.
Duplicate the updates to tkr_mono.cycle_last into tkr_raw.cycle_last,
both need the same value.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150319093400.422589590@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation of adding another tkr field, rename this one to
tkr_mono. Also rename tk_read_base::base_mono to tk_read_base::base,
since the structure is not specific to CLOCK_MONOTONIC and the mono
name got added to the tk_read_base instance.
Lots of trivial churn.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150319093400.344679419@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Trivial cleanups, to improve the readability of the generic sched_clock() code:
- Improve and standardize comments
- Standardize the coding style
- Use vertical spacing where appropriate
- etc.
No code changed:
md5:
19a053b31e0c54feaeff1492012b019a sched_clock.o.before.asm
19a053b31e0c54feaeff1492012b019a sched_clock.o.after.asm
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently it is possible for an NMI (or FIQ on ARM) to come in
and read sched_clock() whilst update_sched_clock() has locked
the seqcount for writing. This results in the NMI handler
locking up when it calls raw_read_seqcount_begin().
This patch fixes the NMI safety issues by providing banked clock
data. This is a similar approach to the one used in Thomas
Gleixner's 4396e058c52e("timekeeping: Provide fast and NMI safe
access to CLOCK_MONOTONIC").
Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-6-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently update_sched_clock() is marked as notrace but this
function is not called by ftrace. This is trivially fixed by
removing the mark up.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently cd.read_data.suspended is read by the hotpath function
sched_clock(). This variable need not be accessed on the
hotpath. In fact, once it is removed, we can remove the
conditional branches from sched_clock() and install a dummy
read_sched_clock function to suspend the clock.
The new master copy of the function pointer
(actual_read_sched_clock) is introduced and is used for all
reads of the clock hardware except those within sched_clock
itself.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently sched_clock(), a very hot code path, is not optimized
to minimise its cache profile. In particular:
1. cd is not ____cacheline_aligned,
2. struct clock_data does not distinguish between hotpath and
coldpath data, reducing locality of reference in the hotpath,
3. Some hotpath data is missing from struct clock_data and is marked
__read_mostly (which more or less guarantees it will not share a
cache line with cd).
This patch corrects these problems by extracting all hotpath
data into a separate structure and using ____cacheline_aligned
to ensure the hotpath uses a single (64 byte) cache line.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the scope of the raw_write_seqcount_begin/end() in
sched_clock_register() far exceeds the scope of the read section
in sched_clock(). This gives the impression of safety during
cursory review but achieves little.
Note that this is likely to be a latent issue at present because
sched_clock_register() is typically called before we enable
interrupts, however the issue does risk bugs being needlessly
introduced as the code evolves.
This patch fixes the problem by increasing the scope of the read
locking performed by sched_clock() to cover all data modified by
sched_clock_register.
We also improve clarity by moving writes to struct clock_data
that do not impact sched_clock() outside of the critical
section.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
[ Reworked it slightly to apply to tip/timers/core]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The hrtimer mode of broadcast queues hrtimers in the idle entry
path so as to wakeup cpus in deep idle states. The associated
call graph is :
cpuidle_idle_call()
|____ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, ....))
|_____tick_broadcast_set_event()
|____clockevents_program_event()
|____bc_set_next()
The hrtimer_{start/cancel} functions call into tracing which uses RCU.
But it is not legal to call into RCU in cpuidle because it is one of the
quiescent states. Hence protect this region with RCU_NONIDLE which informs
RCU that the cpu is momentarily non-idle.
As an aside it is helpful to point out that the clock event device that is
programmed here is not a per-cpu clock device; it is a
pseudo clock device, used by the broadcast framework alone.
The per-cpu clock device programming never goes through bc_set_next().
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: linuxppc-dev@ozlabs.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Link: http://lkml.kernel.org/r/20150318104705.17763.56668.stgit@preeti.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ingo requested this function be renamed to improve readability,
so I've renamed __clocksource_updatefreq_scale() as well as the
__clocksource_updatefreq_hz/khz() functions to avoid
squishedtogethernames.
This touches some of the sh clocksources, which I've not tested.
The arch/arm/plat-omap change is just a comment change for
consistency.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-13-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Print the mask, max_cycles, and max_idle_ns values for
clocksources being registered.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-12-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A long running project has been to clean up remaining uses
of clocksource_register(), replacing it with the simpler
clocksource_register_khz/hz() functions.
However, there are a few cases where we need to self-define
our mult/shift values, so switch the function to a more
obviously internal __clocksource_register() name, and
consolidate much of the internal logic so we don't have
duplication.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-10-git-send-email-john.stultz@linaro.org
[ Minor cleanups. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The clocksource watchdog reporting has been less helpful
then desired, as it just printed the delta between
the two clocksources. This prevents any useful analysis
of why the skew occurred.
Thus this patch tries to improve the output when we
mark a clocksource as unstable, printing out the cycle
last and now values for both the current clocksource
and the watchdog clocksource. This will allow us to see
if the result was due to a false positive caused by
a problematic watchdog.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-9-git-send-email-john.stultz@linaro.org
[ Minor cleanups of kernel messages. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was suggested that the underflow/overflow protection
should probably throw some sort of warning out, rather
than just silently fixing the issue.
So this patch adds some warnings here. The flag variables
used are not protected by locks, but since we can't print
from the reading functions, just being able to say we
saw an issue in the update interval is useful enough,
and can be slightly racy without real consequence.
The big complication is that we're only under a read
seqlock, so the data could shift under us during
our calculation to see if there was a problem. This
patch avoids this issue by nesting another seqlock
which allows us to snapshot the just required values
atomically. So we shouldn't see false positives.
I also added some basic rate-limiting here, since
on one build machine w/ skewed TSCs it was fairly
noisy at bootup.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-8-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the case where there is a broken clocksource
where there are multiple actual clocks that
aren't perfectly aligned, we may see small "negative"
deltas when we subtract 'now' from 'cycle_last'.
The values are actually negative with respect to the
clocksource mask value, not necessarily negative
if cast to a s64, but we can check by checking the
delta to see if it is a small (relative to the mask)
negative value (again negative relative to the mask).
If so, we assume we jumped backwards somehow and
instead use zero for our delta.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-7-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When calculating the current delta since the last tick, we
currently have no hard protections to prevent a multiplication
overflow from occuring.
This patch introduces infrastructure to allow a cap that
limits the clocksource read delta value to the 'max_cycles' value,
which is where an overflow would occur.
Since this is in the hotpath, it adds the extra checking under
CONFIG_DEBUG_TIMEKEEPING=y.
There was some concern that capping time like this could cause
problems as we may stop expiring timers, which could go circular
if the timer that triggers time accumulation were mis-scheduled
too far in the future, which would cause time to stop.
However, since the mult overflow would result in a smaller time
value, we would effectively have the same problem there.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-6-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recently there's been requests for better sanity
checking in the time code, so that it's more clear
when something is going wrong, since timekeeping issues
could manifest in a large number of strange ways in
various subsystems.
Thus, this patch adds some extra infrastructure to
add a check to update_wall_time() to print two new
warnings:
1) if we see the call delayed beyond the 'max_cycles'
overflow point,
2) or if we see the call delayed beyond the clocksource's
'max_idle_ns' value, which is currently 50% of the
overflow point.
This extra infrastructure is conditional on
a new CONFIG_DEBUG_TIMEKEEPING option, also
added in this patch - default off.
Tested this a bit by halting qemu for specified
lengths of time to trigger the warnings.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-5-git-send-email-john.stultz@linaro.org
[ Improved the changelog and the messages a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to facilitate clocksource validation, add a
'max_cycles' field to the clocksource structure which
will hold the maximum cycle value that can safely be
multiplied without potentially causing an overflow.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The clocksource logic has a number of places where we try to
include a safety margin. Most of these are 12% safety margins,
but they are inconsistently applied and sometimes are applied
on top of each other.
Additionally, in the previous patch, we corrected an issue
where we unintentionally in effect created a 50% safety margin,
which these 12.5% margins where then added to.
So to simplify the logic here, this patch removes the various
12.5% margins, and consolidates adding the margin in one place:
clocks_calc_max_nsecs().
Additionally, Linus prefers a 50% safety margin, as it allows
bad clock values to be more easily caught. This should really
have no net effect, due to the corrected issue earlier which
caused greater then 50% margins to be used w/o issue.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Stephen Boyd <sboyd@codeaurora.org> (for the sched_clock.c bit)
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The previous clocks_calc_max_nsecs() code had some unecessarily
complex bit logic to find the max interval that could cause
multiplication overflows. Since this is not in the hot
path, just do the divide to make it easier to read.
The previous implementation also had a subtle issue
that it avoided overflows with signed 64-bit values, where
as the intervals are always unsigned. This resulted in
overly conservative intervals, which other safety margins
were then added to, reducing the intended interval length.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'v4.0-rc2' into timers/core, to refresh the tree before pulling more changes
It looks like clockevents_unbind is being exported by mistake as:
- it is static;
- it is not listed in include/linux/clockchips.h;
- EXPORT_SYMBOL_GPL(clockevents_unbind) follows clockevents_unbind_device()
implementation.
I think clockevents_unbind_device should be exported instead. This is going to
be used to teardown Hyper-V clockevent devices on module unload.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull ntp fix from Ingo Molnar:
"An adjtimex interface regression fix for 32-bit systems"
[ A check that was added in a previous commit is really only a concern
for 64bit systems, but was applied to both 32 and 64bit systems, which
results in breaking 32bit systems.
Thus the fix here is to make the check only apply to 64bit systems ]
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ntp: Fixup adjtimex freq validation on 32-bit systems
It is not possible for the clockevents core to know which modes (other than
those with a corresponding feature flag) are supported by a particular
implementation. And drivers are expected to handle transition to all modes
elegantly, as ->set_mode() would be issued for them unconditionally.
Now, adding support for a new mode complicates things a bit if we want to use
the legacy ->set_mode() callback. We need to closely review all clockevents
drivers to see if they would break on addition of a new mode. And after such
reviews, it is found that we have to do non-trivial changes to most of the
drivers [1].
Introduce mode-specific set_mode_*() callbacks, some of which the drivers may or
may not implement. A missing callback would clearly convey the message that the
corresponding mode isn't supported.
A driver may still choose to keep supporting the legacy ->set_mode() callback,
but ->set_mode() wouldn't be supporting any new modes beyond RESUME. If a driver
wants to benefit from using a new mode, it would be required to migrate to
the mode specific callbacks.
The legacy ->set_mode() callback and the newly introduced mode-specific
callbacks are mutually exclusive. Only one of them should be supported by the
driver.
Sanity check is done at the time of registration to distinguish between optional
and required callbacks and to make error recovery and handling simpler. If the
legacy ->set_mode() callback is provided, all mode specific ones would be
ignored by the core but a warning is thrown if they are present.
Call sites calling ->set_mode() directly are also updated to use
__clockevents_set_mode() instead, as ->set_mode() may not be available anymore
for few drivers.
[1] https://lkml.org/lkml/2014/12/9/605
[2] https://lkml.org/lkml/2015/1/23/255
Suggested-by: Thomas Gleixner <tglx@linutronix.de> [2]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Link: http://lkml.kernel.org/r/792d59a40423f0acffc9bb0bec9de1341a06fa02.1423788565.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Additional validation of adjtimex freq values to avoid
potential multiplication overflows were added in commit
5e5aeb4367 (time: adjtimex: Validate the ADJ_FREQUENCY values)
Unfortunately the patch used LONG_MAX/MIN instead of
LLONG_MAX/MIN, which was fine on 64-bit systems, but being
much smaller on 32-bit systems caused false positives
resulting in most direct frequency adjustments to fail w/
EINVAL.
ntpd only does direct frequency adjustments at startup, so
the issue was not as easily observed there, but other time
sync applications like ptpd and chrony were more effected by
the bug.
See bugs:
https://bugzilla.kernel.org/show_bug.cgi?id=92481https://bugzilla.redhat.com/show_bug.cgi?id=1188074
This patch changes the checks to use LLONG_MAX for
clarity, and additionally the checks are disabled
on 32-bit systems since LLONG_MAX/PPM_SCALE is always
larger then the 32-bit long freq value, so multiplication
overflows aren't possible there.
Reported-by: Josh Boyer <jwboyer@fedoraproject.org>
Reported-by: George Joseph <george.joseph@fairview5.com>
Tested-by: George Joseph <george.joseph@fairview5.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v3.19+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/r/1423553436-29747-1-git-send-email-john.stultz@linaro.org
[ Prettified the changelog and the comments a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Till now suspend-to-idle has not been able to save much more energy
than runtime PM because of timer interrupts that periodically bring
CPUs out of idle while they are waiting for a wakeup interrupt. Of
course, the timer interrupts are not wakeup ones, so the handling of
them can be deferred until a real wakeup interrupt happens, but at
the same time we don't want to mass-expire timers at that point.
The solution is to suspend the entire timekeeping when the last CPU
is entering an idle state and resume it when the first CPU goes out
of idle. That has to be done with care, though, so as to avoid
accessing suspended clocksources etc. end we need extra support
from idle drivers for that.
This series of commits adds support for quiescing timers during
suspend-to-idle and adds the requisite callbacks to intel_idle
and the ACPI cpuidle driver.
/
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Merge tag 'suspend-to-idle-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull suspend-to-idle updates from Rafael Wysocki:
"Suspend-to-idle timer quiescing support for v3.20-rc1
Until now suspend-to-idle has not been able to save much more energy
than runtime PM because of timer interrupts that periodically bring
CPUs out of idle while they are waiting for a wakeup interrupt. Of
course, the timer interrupts are not wakeup ones, so the handling of
them can be deferred until a real wakeup interrupt happens, but at the
same time we don't want to mass-expire timers at that point.
The solution is to suspend the entire timekeeping when the last CPU is
entering an idle state and resume it when the first CPU goes out of
idle. That has to be done with care, though, so as to avoid accessing
suspended clocksources etc. end we need extra support from idle
drivers for that.
This series of commits adds support for quiescing timers during
suspend-to-idle and adds the requisite callbacks to intel_idle and the
ACPI cpuidle driver"
* tag 'suspend-to-idle-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI / idle: Implement ->enter_freeze callback routine
intel_idle: Add ->enter_freeze callbacks
PM / sleep: Make it possible to quiesce timers during suspend-to-idle
timekeeping: Make it safe to use the fast timekeeper while suspended
timekeeping: Pass readout base to update_fast_timekeeper()
PM / sleep: Re-implement suspend-to-idle handling
The efficiency of suspend-to-idle depends on being able to keep CPUs
in the deepest available idle states for as much time as possible.
Ideally, they should only be brought out of idle by system wakeup
interrupts.
However, timer interrupts occurring periodically prevent that from
happening and it is not practical to chase all of the "misbehaving"
timers in a whack-a-mole fashion. A much more effective approach is
to suspend the local ticks for all CPUs and the entire timekeeping
along the lines of what is done during full suspend, which also
helps to keep suspend-to-idle and full suspend reasonably similar.
The idea is to suspend the local tick on each CPU executing
cpuidle_enter_freeze() and to make the last of them suspend the
entire timekeeping. That should prevent timer interrupts from
triggering until an IO interrupt wakes up one of the CPUs. It
needs to be done with interrupts disabled on all of the CPUs,
though, because otherwise the suspended clocksource might be
accessed by an interrupt handler which might lead to fatal
consequences.
Unfortunately, the existing ->enter callbacks provided by cpuidle
drivers generally cannot be used for implementing that, because some
of them re-enable interrupts temporarily and some idle entry methods
cause interrupts to be re-enabled automatically on exit. Also some
of these callbacks manipulate local clock event devices of the CPUs
which really shouldn't be done after suspending their ticks.
To overcome that difficulty, introduce a new cpuidle state callback,
->enter_freeze, that will be guaranteed (1) to keep interrupts
disabled all the time (and return with interrupts disabled) and (2)
not to touch the CPU timer devices. Modify cpuidle_enter_freeze() to
look for the deepest available idle state with ->enter_freeze present
and to make the CPU execute that callback with suspended tick (and the
last of the online CPUs to execute it with suspended timekeeping).
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Theoretically, ktime_get_mono_fast_ns() may be executed after
timekeeping has been suspended (or before it is resumed) which
in turn may lead to undefined behavior, for example, when the
clocksource read from timekeeping_get_ns() called by it is
not accessible at that time.
Prevent that from happening by setting up a dummy readout base for
the fast timekeeper during timekeeping_suspend() such that it will
always return the same number of cycles.
After the last timekeeping_update() in timekeeping_suspend() the
clocksource is read and the result is stored as cycles_at_suspend.
The readout base from the current timekeeper is copied onto the
dummy and the ->read pointer of the dummy is set to a routine
unconditionally returning cycles_at_suspend. Next, the dummy is
passed to update_fast_timekeeper().
Then, ktime_get_mono_fast_ns() will work until the subsequent
timekeeping_resume() and the proper readout base for the fast
timekeeper will be restored by the timekeeping_update() called
right after clearing timekeeping_suspended.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
printk and friends can now format bitmaps using '%*pb[l]'. cpumask
and nodemask also provide cpumask_pr_args() and nodemask_pr_args()
respectively which can be used to generate the two printf arguments
necessary to format the specified cpu/nodemask.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Modify update_fast_timekeeper() to take a struct tk_read_base
pointer as its argument (instead of a struct timekeeper pointer)
and update its kerneldoc comment to reflect that.
That will allow a struct tk_read_base that is not part of a
struct timekeeper to be passed to it in the next patch.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <john.stultz@linaro.org>
If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target. This is because the
restart_block is held in the same memory allocation as the kernel stack.
Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.
Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.
It's also a decent simplification, since the restart code is more or less
identical on all architectures.
[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull networking updates from David Miller:
1) More iov_iter conversion work from Al Viro.
[ The "crypto: switch af_alg_make_sg() to iov_iter" commit was
wrong, and this pull actually adds an extra commit on top of the
branch I'm pulling to fix that up, so that the pre-merge state is
ok. - Linus ]
2) Various optimizations to the ipv4 forwarding information base trie
lookup implementation. From Alexander Duyck.
3) Remove sock_iocb altogether, from CHristoph Hellwig.
4) Allow congestion control algorithm selection via routing metrics.
From Daniel Borkmann.
5) Make ipv4 uncached route list per-cpu, from Eric Dumazet.
6) Handle rfs hash collisions more gracefully, also from Eric Dumazet.
7) Add xmit_more support to r8169, e1000, and e1000e drivers. From
Florian Westphal.
8) Transparent Ethernet Bridging support for GRO, from Jesse Gross.
9) Add BPF packet actions to packet scheduler, from Jiri Pirko.
10) Add support for uniqu flow IDs to openvswitch, from Joe Stringer.
11) New NetCP ethernet driver, from Muralidharan Karicheri and Wingman
Kwok.
12) More sanely handle out-of-window dupacks, which can result in
serious ACK storms. From Neal Cardwell.
13) Various rhashtable bug fixes and enhancements, from Herbert Xu,
Patrick McHardy, and Thomas Graf.
14) Support xmit_more in be2net, from Sathya Perla.
15) Group Policy extensions for vxlan, from Thomas Graf.
16) Remove Checksum Offload support for vxlan, from Tom Herbert.
17) Like ipv4, support lockless transmit over ipv6 UDP sockets. From
Vlad Yasevich.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1494+1 commits)
crypto: fix af_alg_make_sg() conversion to iov_iter
ipv4: Namespecify TCP PMTU mechanism
i40e: Fix for stats init function call in Rx setup
tcp: don't include Fast Open option in SYN-ACK on pure SYN-data
openvswitch: Only set TUNNEL_VXLAN_OPT if VXLAN-GBP metadata is set
ipv6: Make __ipv6_select_ident static
ipv6: Fix fragment id assignment on LE arches.
bridge: Fix inability to add non-vlan fdb entry
net: Mellanox: Delete unnecessary checks before the function call "vunmap"
cxgb4: Add support in cxgb4 to get expansion rom version via ethtool
ethtool: rename reserved1 memeber in ethtool_drvinfo for expansion ROM version
net: dsa: Remove redundant phy_attach()
IB/mlx4: Reset flow support for IB kernel ULPs
IB/mlx4: Always use the correct port for mirrored multicast attachments
net/bonding: Fix potential bad memory access during bonding events
tipc: remove tipc_snprintf
tipc: nl compat add noop and remove legacy nl framework
tipc: convert legacy nl stats show to nl compat
tipc: convert legacy nl net id get to nl compat
tipc: convert legacy nl net id set to nl compat
...
Pull timer updates from Ingo Molnar:
"The main changes in this cycle were:
- rework hrtimer expiry calculation in hrtimer_interrupt(): the
previous code had a subtle bug where expiry caching would miss an
expiry, resulting in occasional bogus (late) expiry of hrtimers.
- continuing Y2038 fixes
- ktime division optimization
- misc smaller fixes and cleanups"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hrtimer: Make __hrtimer_get_next_event() static
rtc: Convert rtc_set_ntp_time() to use timespec64
rtc: Remove redundant rtc_valid_tm() from rtc_hctosys()
rtc: Modify rtc_hctosys() to address y2038 issues
rtc: Update rtc-dev to use y2038-safe time interfaces
rtc: Update interface.c to use y2038-safe time interfaces
time: Expose get_monotonic_boottime64 for in-kernel use
time: Expose getboottime64 for in-kernel uses
ktime: Optimize ktime_divns for constant divisors
hrtimer: Prevent stale expiry time in hrtimer_interrupt()
ktime.h: Introduce ktime_ms_delta
I noticed some CLOCK_TAI timer test failures on one of my
less-frequently used configurations. And after digging in I
found in 76f4108892 (Cleanup hrtimer accessors to the
timekepeing state), the hrtimer_get_softirq_time tai offset
calucation was incorrectly rewritten, as the tai offset we
return shold be from CLOCK_MONOTONIC, and not CLOCK_REALTIME.
This results in CLOCK_TAI timers expiring early on non-highres
capable machines.
This patch fixes the issue, calculating the tai time properly
from the monotonic base.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable <stable@vger.kernel.org> # 3.17+
Link: http://lkml.kernel.org/r/1423097126-10236-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Conflicts:
arch/arm/boot/dts/imx6sx-sdb.dts
net/sched/cls_bpf.c
Two simple sets of overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull timer fixes from Thomas Gleixner:
"A set of small fixes:
- regression fix for exynos_mct clocksource
- trivial build fix for kona clocksource
- functional one liner fix for the sh_tmu clocksource
- two validation fixes to prevent (root only) data corruption in the
kernel via settimeofday and adjtimex. Tagged for stable"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: adjtimex: Validate the ADJ_FREQUENCY values
time: settimeofday: Validate the values of tv from user
clocksource: sh_tmu: Set cpu_possible_mask to fix SMP broadcast
clocksource: kona: fix __iomem annotation
clocksource: exynos_mct: Fix bitmask regression for exynos4_mct_write
kernel/time/hrtimer.c:444:9: sparse: symbol '__hrtimer_get_next_event' was not declared. Should it be static?
Fixes: 9bc7491906 hrtimer: Prevent stale expiry time in hrtimer_interrupt()
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: kbuild-all@01.org
Link: http://lkml.kernel.org/r/20150123121206.GA4766@snb
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ktime division optimization
* Expose a few more y2038-safe timekeeping interfaces
* RTC core changes to address y2038
Signed-off-by: John Stultz <john.stultz@linaro.org>
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Merge tag 'fortglx-3.20-time' of https://git.linaro.org/people/john.stultz/linux into timers/core
Pull time updates from John Stultz for 3.20:
* ktime division optimization
* Expose a few more y2038-safe timekeeping interfaces
* RTC core changes to address y2038
rtc_set_ntp_time() uses timespec which is y2038-unsafe,
so modify to use timespec64 which is y2038-safe, then
replace rtc_time_to_tm() with rtc_time64_to_tm().
Also adjust all its call sites(only NTP uses it) accordingly.
Cc: pang.xunlei <pang.xunlei@linaro.org>
Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Adds a timespec64 based getboottime64() implementation
that can be used as we convert internal users of
getboottime away from using timespecs.
Cc: pang.xunlei <pang.xunlei@linaro.org>
Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
At least on ARM, do_div() is optimized to turn constant divisors into
an inline multiplication by the reciprocal value at compile time.
However this optimization is missed entirely whenever ktime_divns() is
used and the slow out-of-line division code is used all the time.
Let ktime_divns() use do_div() inline whenever the divisor is constant
and small enough. This will make things like ktime_to_us() and
ktime_to_ms() much faster.
Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nicolas Pitre <nico@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
hrtimer_interrupt() has the following subtle issue:
hrtimer_interrupt()
lock(cpu_base);
expires_next = KTIME_MAX;
expire_timers(CLOCK_MONOTONIC);
expires = get_next_timer(CLOCK_MONOTONIC);
if (expires < expires_next)
expires_next = expires;
expire_timers(CLOCK_REALTIME);
unlock(cpu_base);
wakeup()
hrtimer_start(CLOCK_MONOTONIC, newtimer);
lock(cpu_base();
expires = get_next_timer(CLOCK_REALTIME);
if (expires < expires_next)
expires_next = expires;
So because we already evaluated the next expiring timer of
CLOCK_MONOTONIC we ignore that the expiry time of newtimer might be
earlier than the overall next expiry time in hrtimer_interrupt().
To solve this, remove the caching of the next expiry value from
hrtimer_interrupt() and reevaluate all active clock bases for the next
expiry value. To avoid another code duplication, create a shared
evaluation function and use it for hrtimer_get_next_event(),
hrtimer_force_reprogram() and hrtimer_interrupt().
There is another subtlety in this mechanism:
While hrtimer_interrupt() is running, we want to avoid to touch the
hardware device because we will reprogram it anyway at the end of
hrtimer_interrupt(). This works nicely for hrtimers which get rearmed
via the HRTIMER_RESTART mechanism, because we drop out when the
callback on that CPU is running. But that fails, if a new timer gets
enqueued like in the example above.
This has another implication: While hrtimer_interrupt() is running we
refuse remote enqueueing of timers - see hrtimer_interrupt() and
hrtimer_check_target().
hrtimer_interrupt() tries to prevent this by setting cpu_base->expires
to KTIME_MAX, but that fails if a new timer gets queued.
Prevent both the hardware access and the remote enqueue
explicitely. We can loosen the restriction on the remote enqueue now
due to reevaluation of the next expiry value, but that needs a
seperate patch.
Folded in a fix from Vignesh Radhakrishnan.
Reported-and-tested-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Based-on-patch-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: vigneshr@codeaurora.org
Cc: john.stultz@linaro.org
Cc: viresh.kumar@linaro.org
Cc: fweisbec@gmail.com
Cc: cl@linux.com
Cc: stuart.w.hayes@gmail.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1501202049190.5526@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Verify that the frequency value from userspace is valid and makes sense.
Unverified values can cause overflows later on.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
[jstultz: Fix up bug for negative values and drop redunent cap check]
Signed-off-by: John Stultz <john.stultz@linaro.org>
An unvalidated user input is multiplied by a constant, which can result in
an undefined behaviour for large values. While this is validated later,
we should avoid triggering undefined behaviour.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
[jstultz: include trivial milisecond->microsecond correction noticed
by Andy]
Signed-off-by: John Stultz <john.stultz@linaro.org>
The current timecounter implementation will drop a variable amount
of resolution, depending on the magnitude of the time delta. In
other words, reading the clock too often or too close to a time
stamp conversion will introduce errors into the time values. This
patch fixes the issue by introducing a fractional nanosecond field
that accumulates the low order bits.
Reported-by: Janusz Użycki <j.uzycki@elproma.com.pl>
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The timecounter code has almost nothing to do with the clocksource
code. Let it live in its own file. This will help isolate the
timecounter users from the clocksource users in the source tree.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull NOHZ update from Thomas Gleixner:
"Remove the call into the nohz idle code from the fake 'idle' thread in
the powerclamp driver along with the export of those functions which
was smuggeled in via the thermal tree. People have tried to hack
around it in the nohz core code, but it just violates all rightful
assumptions of that code about the only valid calling context (i.e.
the proper idle task).
The powerclamp trainwreck will still work, it just wont get the
benefit of long idle sleeps"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/powerclamp: Remove tick_nohz_idle abuse
commit 4dbd27711c "tick: export nohz tick idle symbols for module
use" was merged via the thermal tree without an explicit ack from the
relevant maintainers.
The exports are abused by the intel powerclamp driver which implements
a fake idle state from a sched FIFO task. This causes all kinds of
wreckage in the NOHZ core code which rightfully assumes that
tick_nohz_idle_enter/exit() are only called from the idle task itself.
Recent changes in the NOHZ core lead to a failure of the powerclamp
driver and now people try to hack completely broken and backwards
workarounds into the NOHZ core code. This is completely unacceptable
and just papers over the real problem. There are way more subtle
issues lurking around the corner.
The real solution is to fix the powerclamp driver by rewriting it with
a sane concept, but that's beyond the scope of this.
So the only solution for now is to remove the calls into the core NOHZ
code from the powerclamp trainwreck along with the exports.
Fixes: d6d71ee4a1 "PM: Introduce Intel PowerClamp Driver"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Pan Jacob jun <jacob.jun.pan@intel.com>
Cc: LKP <lkp@01.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412181110110.17382@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull drm updates from Dave Airlie:
"Highlights:
- AMD KFD driver merge
This is the AMD HSA interface for exposing a lowlevel interface for
GPGPU use. They have an open source userspace built on top of this
interface, and the code looks as good as it was going to get out of
tree.
- Initial atomic modesetting work
The need for an atomic modesetting interface to allow userspace to
try and send a complete set of modesetting state to the driver has
arisen, and been suffering from neglect this past year. No more,
the start of the common code and changes for msm driver to use it
are in this tree. Ongoing work to get the userspace ioctl finished
and the code clean will probably wait until next kernel.
- DisplayID 1.3 and tiled monitor exposed to userspace.
Tiled monitor property is now exposed for userspace to make use of.
- Rockchip drm driver merged.
- imx gpu driver moved out of staging
Other stuff:
- core:
panel - MIPI DSI + new panels.
expose suggested x/y properties for virtual GPUs
- i915:
Initial Skylake (SKL) support
gen3/4 reset work
start of dri1/ums removal
infoframe tracking
fixes for lots of things.
- nouveau:
tegra k1 voltage support
GM204 modesetting support
GT21x memory reclocking work
- radeon:
CI dpm fixes
GPUVM improvements
Initial DPM fan control
- rcar-du:
HDMI support added
removed some support for old boards
slave encoder driver for Analog Devices adv7511
- exynos:
Exynos4415 SoC support
- msm:
a4xx gpu support
atomic helper conversion
- tegra:
iommu support
universal plane support
ganged-mode DSI support
- sti:
HDMI i2c improvements
- vmwgfx:
some late fixes.
- qxl:
use suggested x/y properties"
* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits)
drm: sti: fix module compilation issue
drm/i915: save/restore GMBUS freq across suspend/resume on gen4
drm: sti: correctly cleanup CRTC and planes
drm: sti: add HQVDP plane
drm: sti: add cursor plane
drm: sti: enable auxiliary CRTC
drm: sti: fix delay in VTG programming
drm: sti: prepare sti_tvout to support auxiliary crtc
drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off}
drm: sti: fix hdmi avi infoframe
drm: sti: remove event lock while disabling vblank
drm: sti: simplify gdp code
drm: sti: clear all mixer control
drm: sti: remove gpio for HDMI hot plug detection
drm: sti: allow to change hdmi ddc i2c adapter
drm/doc: Document drm_add_modes_noedid() usage
drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
drm: Zero out DRM object memory upon cleanup
drm/i915/bdw: Fix the write setting up the WIZ hashing mode
...
Pull percpu updates from Tejun Heo:
"Nothing interesting. A patch to convert the remaining __get_cpu_var()
users, another to fix non-critical off-by-one in an assertion and a
cosmetic conversion to lockless_dereference() in percpu-ref.
The back-merge from mainline is to receive lockless_dereference()"
* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: Replace smp_read_barrier_depends() with lockless_dereference()
percpu: Convert remaining __get_cpu_var uses in 3.18-rcX
percpu: off by one in BUG_ON()
Pull more 2038 timer work from Thomas Gleixner:
"Two more patches for the ongoing 2038 work:
- New accessors to clock MONOTONIC and REALTIME seconds
This is a seperate branch as Arnd has follow up work depending on
this"
* 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Provide y2038 safe accessor to the seconds portion of CLOCK_REALTIME
timekeeping: Provide fast accessor to the seconds part of CLOCK_MONOTONIC
Pull timer core updates from Thomas Gleixner:
"The time(r) departement provides:
- more infrastructure work on the year 2038 issue
- a few fixes in the Armada SoC timers
- the usual pile of fixlets and improvements"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource: armada-370-xp: Use the reference clock on A375 SoC
watchdog: orion: Use the reference clock on Armada 375 SoC
clocksource: armada-370-xp: Add missing clock enable
time: Fix sign bug in NTP mult overflow warning
time: Remove timekeeping_inject_sleeptime()
rtc: Update suspend/resume timing to use 64bit time
rtc/lib: Provide y2038 safe rtc_tm_to_time()/rtc_time_to_tm() replacement
time: Fixup comments to reflect usage of timespec64
time: Expose get_monotonic_coarse64() for in-kernel uses
time: Expose getrawmonotonic64 for in-kernel uses
time: Provide y2038 safe mktime() replacement
time: Provide y2038 safe timekeeping_inject_sleeptime() replacement
time: Provide y2038 safe do_settimeofday() replacement
time: Complete NTP adjustment threshold judging conditions
time: Avoid possible NTP adjustment mult overflow.
time: Rename udelay_test.c to test_udelay.c
clocksource: sirf: Remove hard-coded clock rate
Pull RCU updates from Ingo Molnar:
"These are the main changes in this cycle:
- Streamline RCU's use of per-CPU variables, shifting from "cpu"
arguments to functions to "this_"-style per-CPU variable
accessors.
- signal-handling RCU updates.
- real-time updates.
- torture-test updates.
- miscellaneous fixes.
- documentation updates"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
rcu: Fix FIXME in rcu_tasks_kthread()
rcu: More info about potential deadlocks with rcu_read_unlock()
rcu: Optimize cond_resched_rcu_qs()
rcu: Add sparse check for RCU_INIT_POINTER()
documentation: memory-barriers.txt: Correct example for reorderings
documentation: Add atomic_long_t to atomic_ops.txt
documentation: Additional restriction for control dependencies
documentation: Document RCU self test boot params
rcutorture: Fix rcu_torture_cbflood() memory leak
rcutorture: Remove obsolete kversion param in kvm.sh
rcutorture: Remove stale test configurations
rcutorture: Enable RCU self test in configs
rcutorture: Add early boot self tests
torture: Run Linux-kernel binary out of results directory
cpu: Avoid puts_pending overflow
rcu: Remove "cpu" argument to rcu_cleanup_after_idle()
rcu: Remove "cpu" argument to rcu_prepare_for_idle()
rcu: Remove "cpu" argument to rcu_needs_cpu()
rcu: Remove "cpu" argument to rcu_note_context_switch()
rcu: Remove "cpu" argument to rcu_preempt_check_callbacks()
...
We've lost the +1 required for correct timeouts in
commit 5ed0bdf21a
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Wed Jul 16 21:05:06 2014 +0000
drm: i915: Use nsec based interfaces
Use ktime_get_raw_ns() and get rid of the back and forth timespec
conversions.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: John Stultz <john.stultz@linaro.org>
So fix this up by reinstating our handrolled _timeout function. While
at it bother with handling MAX_JIFFIES.
v2: Convert to usecs (we don't care about the accuracy anyway) first
to avoid overflow issues Dave Gordon spotted.
v3: Drop the explicit MAX_JIFFY_OFFSET check, usecs_to_jiffies should
take care of that already. It might be a bit too enthusiastic about it
though.
v4: Chris has a much nicer color, so use his implementation.
This requires to export nsec_to_jiffies from time.c.
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82749
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
In commit 6067dc5a8c ("time: Avoid possible NTP adjustment
mult overflow") a new check was added to watch for adjustments
that could cause a mult overflow.
Unfortunately the check compares a signed with unsigned value
and ignored the case where the adjustment was negative, which
causes spurious warn-ons on some systems (and seems like it
would result in problematic time adjustments there as well, due
to the early return).
Thus this patch adds a check to make sure the adjustment is
positive before we check for an overflow, and resovles the issue
in my testing.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Debugged-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1416890145-30048-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix up a few comments that weren't updated when the
functions were converted to use timespec64 structures.
Acked-by: Arnd Bergmann <arnd.bergmann@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Adds a timespec64 based get_monotonic_coarse64() implementation
that can be used as we convert internal users of
get_monotonic_coarse away from using timespecs.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Adds a timespec64 based getrawmonotonic64() implementation
that can be used as we convert internal users of
getrawmonotonic away from using timespecs.
Signed-off-by: John Stultz <john.stultz@linaro.org>
As part of addressing "y2038 problem" for in-kernel uses, this
patch adds safe mktime64() using time64_t.
After this patch, mktime() is deprecated and all its call sites
will be fixed using mktime64(), after that it can be removed.
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
As part of addressing "y2038 problem" for in-kernel uses, this
patch adds timekeeping_inject_sleeptime64() using timespec64.
After this patch, timekeeping_inject_sleeptime() is deprecated
and all its call sites will be fixed using the new interface,
after that it can be removed.
NOTE: timekeeping_inject_sleeptime() is safe actually, but we
want to eliminate timespec eventually, so comes this patch.
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The kernel uses 32-bit signed value(time_t) for seconds elapsed
1970-01-01:00:00:00, thus it will overflow at 2038-01-19 03:14:08
on 32-bit systems. This is widely known as the y2038 problem.
As part of addressing "y2038 problem" for in-kernel uses, this patch
adds safe do_settimeofday64() using timespec64.
After this patch, do_settimeofday() is deprecated and all its call
sites will be fixed using do_settimeofday64(), after that it can be
removed.
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The clocksource mult-adjustment threshold is [mult-maxadj, mult+maxadj],
timekeeping_adjust() only deals with the upper threshold, but misses the
lower threshold.
This patch adds the lower threshold judging condition.
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
[jstultz: Minor fix for > 80 char line]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Ideally, __clocksource_updatefreq_scale, selects the largest shift
value possible for a clocksource. This results in the mult memember of
struct clocksource being particularly large, although not so large
that NTP would adjust the clock to cause it to overflow.
That said, nothing actually prohibits an overflow from occuring, its
just that it "shouldn't" occur.
So while very unlikely, and so far never observed, the value of
(cs->mult+cs->maxadj) may have a chance to reach very near 0xFFFFFFFF,
so there is a possibility it may overflow when doing NTP positive
adjustment
See the following detail: When NTP slewes the clock, kernel goes
through update_wall_time()->...->timekeeping_apply_adjustment():
tk->tkr.mult += mult_adj;
Since there is no guard against it, its possible tk->tkr.mult may
overflow during this operation.
This patch avoids any possible mult overflow by judging the overflow
case before adding mult_adj to mult, also adds the WARNING message
when capturing such case.
Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
[jstultz: Reworded commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Kees requested that this test module be renamed for consistency sake,
so this patch renames the udelay_test.c file (recently added to
tip/timers/core for 3.17) to test_udelay.c
Cc: Kees Cook <keescook@chromium.org>
Cc: Greg KH <greg@kroah.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Linux-Next <linux-next@vger.kernel.org>
Cc: David Riley <davidriley@chromium.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
While looking over the cpu-timer code I found that we appear to add
the delta for the calling task twice, through:
cpu_timer_sample_group()
thread_group_cputimer()
thread_group_cputime()
times->sum_exec_runtime += task_sched_runtime();
*sample = cputime.sum_exec_runtime + task_delta_exec();
Which would make the sample run ahead, making the sleep short.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20141112113737.GI10476@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The "cpu" argument to rcu_needs_cpu() is always the current CPU, so drop
it. This in turn allows the "cpu" argument to rcu_cpu_has_callbacks()
to be removed, which allows the uses of "cpu" in both functions to be
replaced with a this_cpu_ptr(). Again, the anticipated cross-CPU uses
of these functions has been replaced by NO_HZ_FULL.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
The "cpu" argument was kept around on the off-chance that RCU might
offload scheduler-clock interrupts. However, this offload approach
has been replaced by NO_HZ_FULL, which offloads -all- RCU processing
from qualifying CPUs. It is therefore time to remove the "cpu" argument
to rcu_check_callbacks(), which this commit does.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
During the 3.18 merge period additional __get_cpu_var uses were
added. The patch converts these to this_cpu_ptr().
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
ktime_get_real_seconds() is the replacement function for get_seconds()
returning the seconds portion of CLOCK_REALTIME in a time64_t. For
64bit the function is equivivalent to get_seconds(), but for 32bit it
protects the readout with the timekeeper sequence count. This is
required because 32-bit machines cannot access 64-bit tk->xtime_sec
variable atomically.
[tglx: Massaged changelog and added docbook comment ]
Signed-off-by: Heena Sirwani <heenasirwani@gmail.com>
Reviewed-by: Arnd Bergman <arnd@arndb.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: opw-kernel@googlegroups.com
Link: http://lkml.kernel.org/r/7adcfaa8962b8ad58785d9a2456c3f77d93c0ffb.1414578445.git.heenasirwani@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This is the counterpart to get_seconds() based on CLOCK_MONOTONIC. The
use case for this interface are kernel internal coarse grained
timestamps which do neither require the nanoseconds fraction of
current time nor the CLOCK_REALTIME properties. Such timestamps can
currently only retrieved by calling ktime_get_ts64() and using the
tv_sec field of the returned timespec64. That's inefficient as it
involves the read of the clocksource, math operations and must be
protected by the timekeeper sequence counter.
To avoid the sequence counter protection we restrict the return value
to unsigned 32bit on 32bit machines. This covers ~136 years of uptime
and therefor an overflow is not expected to hit anytime soon.
To avoid math in the function we calculate the current seconds portion
of CLOCK_MONOTONIC when the timekeeper gets updated in
tk_update_ktime_data() similar to the CLOCK_REALTIME counterpart
xtime_sec.
[ tglx: Massaged changelog, simplified and commented the update
function, added docbook comment ]
Signed-off-by: Heena Sirwani <heenasirwani@gmail.com>
Reviewed-by: Arnd Bergman <arnd@arndb.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: opw-kernel@googlegroups.com
Link: http://lkml.kernel.org/r/da0b63f4bdf3478909f92becb35861197da3a905.1414578445.git.heenasirwani@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Andrey reported that on a kernel with UBSan enabled he found:
UBSan: Undefined behaviour in ../kernel/time/clockevents.c:75:34
I guess it should be 1ULL here instead of 1U:
(!ismax || evt->mult <= (1U << evt->shift)))
That's indeed the correct solution because shift might be 32.
Reported-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If userland creates a timer without specifying a sigevent info, we'll
create one ourself, using a stack local variable. Particularly will we
use the timer ID as sival_int. But as sigev_value is a union containing
a pointer and an int, that assignment will only partially initialize
sigev_value on systems where the size of a pointer is bigger than the
size of an int. On such systems we'll copy the uninitialized stack bytes
from the timer_create() call to userland when the timer actually fires
and we're going to deliver the signal.
Initialize sigev_value with 0 to plug the stack info leak.
Found in the PaX patch, written by the PaX Team.
Fixes: 5a9fa73072 ("posix-timers: kill ->it_sigev_signo and...")
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: PaX Team <pageexec@freemail.hu>
Cc: <stable@vger.kernel.org> # v2.6.28+
Link: http://lkml.kernel.org/r/1412456799-32339-1-git-send-email-minipli@googlemail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull percpu consistent-ops changes from Tejun Heo:
"Way back, before the current percpu allocator was implemented, static
and dynamic percpu memory areas were allocated and handled separately
and had their own accessors. The distinction has been gone for many
years now; however, the now duplicate two sets of accessors remained
with the pointer based ones - this_cpu_*() - evolving various other
operations over time. During the process, we also accumulated other
inconsistent operations.
This pull request contains Christoph's patches to clean up the
duplicate accessor situation. __get_cpu_var() uses are replaced with
with this_cpu_ptr() and __this_cpu_ptr() with raw_cpu_ptr().
Unfortunately, the former sometimes is tricky thanks to C being a bit
messy with the distinction between lvalues and pointers, which led to
a rather ugly solution for cpumask_var_t involving the introduction of
this_cpu_cpumask_var_ptr().
This converts most of the uses but not all. Christoph will follow up
with the remaining conversions in this merge window and hopefully
remove the obsolete accessors"
* 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (38 commits)
irqchip: Properly fetch the per cpu offset
percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t -fix
ia64: sn_nodepda cannot be assigned to after this_cpu conversion. Use __this_cpu_write.
percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t
Revert "powerpc: Replace __get_cpu_var uses"
percpu: Remove __this_cpu_ptr
clocksource: Replace __this_cpu_ptr with raw_cpu_ptr
sparc: Replace __get_cpu_var uses
avr32: Replace __get_cpu_var with __this_cpu_write
blackfin: Replace __get_cpu_var uses
tile: Use this_cpu_ptr() for hardware counters
tile: Replace __get_cpu_var uses
powerpc: Replace __get_cpu_var uses
alpha: Replace __get_cpu_var
ia64: Replace __get_cpu_var uses
s390: cio driver &__get_cpu_var replacements
s390: Replace __get_cpu_var uses
mips: Replace __get_cpu_var uses
MIPS: Replace __get_cpu_var uses in FPU emulator.
arm: Replace __this_cpu_ptr with raw_cpu_ptr
...
Pull s390 updates from Martin Schwidefsky:
"This patch set contains the main portion of the changes for 3.18 in
regard to the s390 architecture. It is a bit bigger than usual,
mainly because of a new driver and the vector extension patches.
The interesting bits are:
- Quite a bit of work on the tracing front. Uprobes is enabled and
the ftrace code is reworked to get some of the lost performance
back if CONFIG_FTRACE is enabled.
- To improve boot time with CONFIG_DEBIG_PAGEALLOC, support for the
IPTE range facility is added.
- The rwlock code is re-factored to improve writer fairness and to be
able to use the interlocked-access instructions.
- The kernel part for the support of the vector extension is added.
- The device driver to access the CD/DVD on the HMC is added, this
will hopefully come in handy to improve the installation process.
- Add support for control-unit initiated reconfiguration.
- The crypto device driver is enhanced to enable the additional AP
domains and to allow the new crypto hardware to be used.
- Bug fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (39 commits)
s390/ftrace: simplify enabling/disabling of ftrace_graph_caller
s390/ftrace: remove 31 bit ftrace support
s390/kdump: add support for vector extension
s390/disassembler: add vector instructions
s390: add support for vector extension
s390/zcrypt: Toleration of new crypto hardware
s390/idle: consolidate idle functions and definitions
s390/nohz: use a per-cpu flag for arch_needs_cpu
s390/vtime: do not reset idle data on CPU hotplug
s390/dasd: add support for control unit initiated reconfiguration
s390/dasd: fix infinite loop during format
s390/mm: make use of ipte range facility
s390/setup: correct 4-level kernel page table detection
s390/topology: call set_sched_topology early
s390/uprobes: architecture backend for uprobes
s390/uprobes: common library for kprobes and uprobes
s390/rwlock: use the interlocked-access facility 1 instructions
s390/rwlock: improve writer fairness
s390/rwlock: remove interrupt-enabling rwlock variant.
s390/mm: remove change bit override support
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Optimized support for Intel "Cluster-on-Die" (CoD) topologies (Dave
Hansen)
- Various sched/idle refinements for better idle handling (Nicolas
Pitre, Daniel Lezcano, Chuansheng Liu, Vincent Guittot)
- sched/numa updates and optimizations (Rik van Riel)
- sysbench speedup (Vincent Guittot)
- capacity calculation cleanups/refactoring (Vincent Guittot)
- Various cleanups to thread group iteration (Oleg Nesterov)
- Double-rq-lock removal optimization and various refactorings
(Kirill Tkhai)
- various sched/deadline fixes
... and lots of other changes"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
sched/dl: Use dl_bw_of() under rcu_read_lock_sched()
sched/fair: Delete resched_cpu() from idle_balance()
sched, time: Fix build error with 64 bit cputime_t on 32 bit systems
sched: Improve sysbench performance by fixing spurious active migration
sched/x86: Fix up typo in topology detection
x86, sched: Add new topology for multi-NUMA-node CPUs
sched/rt: Use resched_curr() in task_tick_rt()
sched: Use rq->rd in sched_setaffinity() under RCU read lock
sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask'
sched: Use dl_bw_of() under RCU read lock
sched/fair: Remove duplicate code from can_migrate_task()
sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW
sched: print_rq(): Don't use tasklist_lock
sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()
sched: Fix the task-group check in tg_has_rt_tasks()
sched/fair: Leverage the idle state info when choosing the "idlest" cpu
sched: Let the scheduler see CPU idle states
sched/deadline: Fix inter- exclusive cpusets migrations
sched/deadline: Clear dl_entity params when setscheduling to different class
sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()
...
Pull timer updates from Thomas Gleixner:
"Nothing really exciting this time:
- a few fixlets in the NOHZ code
- a new ARM SoC timer abomination. One should expect that we have
enough of them already, but they insist on inventing new ones.
- the usual bunch of ARM SoC timer updates. That feels like herding
cats"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource: arm_arch_timer: Consolidate arch_timer_evtstrm_enable
clocksource: arm_arch_timer: Enable counter access for 32-bit ARM
clocksource: arm_arch_timer: Change clocksource name if CP15 unavailable
clocksource: sirf: Disable counter before re-setting it
clocksource: cadence_ttc: Add support for 32bit mode
clocksource: tcb_clksrc: Sanitize IRQ request
clocksource: arm_arch_timer: Discard unavailable timers correctly
clocksource: vf_pit_timer: Support shutdown mode
ARM: meson6: clocksource: Add Meson6 timer support
ARM: meson: documentation: Add timer documentation
clocksource: sh_tmu: Document r8a7779 binding
clocksource: sh_mtu2: Document r7s72100 binding
clocksource: sh_cmt: Document SoC specific bindings
timerfd: Remove an always true check
nohz: Avoid tick's double reprogramming in highres mode
nohz: Fix spurious periodic tick behaviour in low-res dynticks mode
Pull timer fixes from Ingo Molnar:
"Main changes:
- Fix the deadlock reported by Dave Jones et al
- Clean up and fix nohz_full interaction with arch abilities
- nohz init code consolidation/cleanup"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz: nohz full depends on irq work self IPI support
nohz: Consolidate nohz full init code
arm64: Tell irq work about self IPI support
arm: Tell irq work about self IPI support
x86: Tell irq work about self IPI support
irq_work: Force raised irq work to run on irq work interrupt
irq_work: Introduce arch_irq_work_has_interrupt()
nohz: Move nohz full init call to tick init
Move the nohz_delay bit from the s390_idle data structure to the
per-cpu flags. Clear the nohz delay flag in __cpu_disable and
remove the cpu hotplug notifier that used to do this.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The nohz full functionality depends on IRQ work to trigger its own
interrupts. As it's used to restart the tick, we can't rely on the tick
fallback for irq work callbacks, ie: we can't use the tick to restart
the tick itself.
Lets reject the full dynticks initialization if that arch support isn't
available.
As a side effect, this makes sure that nohz kick is never called from
the tick. That otherwise would result in illegal hrtimer self-cancellation
and lockup.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The supports for CONFIG_NO_HZ_FULL_ALL=y and the nohz_full= kernel
parameter both have their own way to do the same thing: allocate
full dynticks cpumasks, fill them and initialize some state variables.
Lets consolidate that all in the same place.
While at it, convert some regular printk message to warnings when
fundamental allocations fail.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The nohz full kick, which restarts the tick when any resource depend
on it, can't be executed anywhere given the operation it does on timers.
If it is called from the scheduler or timers code, chances are that
we run into a deadlock.
This is why we run the nohz full kick from an irq work. That way we make
sure that the kick runs on a virgin context.
However if that's the case when irq work runs in its own dedicated
self-ipi, things are different for the big bunch of archs that don't
support the self triggered way. In order to support them, irq works are
also handled by the timer interrupt as fallback.
Now when irq works run on the timer interrupt, the context isn't blank.
More precisely, they can run in the context of the hrtimer that runs the
tick. But the nohz kick cancels and restarts this hrtimer and cancelling
an hrtimer from itself isn't allowed. This is why we run in an endless
loop:
Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 2
CPU: 2 PID: 7538 Comm: kworker/u8:8 Not tainted 3.16.0+ #34
Workqueue: btrfs-endio-write normal_work_helper [btrfs]
ffff880244c06c88 000000001b486fe1 ffff880244c06bf0 ffffffff8a7f1e37
ffffffff8ac52a18 ffff880244c06c78 ffffffff8a7ef928 0000000000000010
ffff880244c06c88 ffff880244c06c20 000000001b486fe1 0000000000000000
Call Trace:
<NMI[<ffffffff8a7f1e37>] dump_stack+0x4e/0x7a
[<ffffffff8a7ef928>] panic+0xd4/0x207
[<ffffffff8a1450e8>] watchdog_overflow_callback+0x118/0x120
[<ffffffff8a186b0e>] __perf_event_overflow+0xae/0x350
[<ffffffff8a184f80>] ? perf_event_task_disable+0xa0/0xa0
[<ffffffff8a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
[<ffffffff8a187934>] perf_event_overflow+0x14/0x20
[<ffffffff8a020386>] intel_pmu_handle_irq+0x206/0x410
[<ffffffff8a01937b>] perf_event_nmi_handler+0x2b/0x50
[<ffffffff8a007b72>] nmi_handle+0xd2/0x390
[<ffffffff8a007aa5>] ? nmi_handle+0x5/0x390
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a008062>] default_do_nmi+0x72/0x1c0
[<ffffffff8a008268>] do_nmi+0xb8/0x100
[<ffffffff8a7ff66a>] end_repeat_nmi+0x1e/0x2e
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
<<EOE><IRQ[<ffffffff8a0ccd2f>] lock_acquired+0xaf/0x450
[<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a7fc678>] _raw_spin_lock_irqsave+0x78/0x90
[<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a0f74c5>] lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a0f7723>] hrtimer_try_to_cancel+0x33/0x1e0
[<ffffffff8a0f78ea>] hrtimer_cancel+0x1a/0x30
[<ffffffff8a109237>] tick_nohz_restart+0x17/0x90
[<ffffffff8a10a213>] __tick_nohz_full_check+0xc3/0x100
[<ffffffff8a10a25e>] nohz_full_kick_work_func+0xe/0x10
[<ffffffff8a17c884>] irq_work_run_list+0x44/0x70
[<ffffffff8a17c8da>] irq_work_run+0x2a/0x50
[<ffffffff8a0f700b>] update_process_times+0x5b/0x70
[<ffffffff8a109005>] tick_sched_handle.isra.21+0x25/0x60
[<ffffffff8a109b81>] tick_sched_timer+0x41/0x60
[<ffffffff8a0f7aa2>] __run_hrtimer+0x72/0x470
[<ffffffff8a109b40>] ? tick_sched_do_timer+0xb0/0xb0
[<ffffffff8a0f8707>] hrtimer_interrupt+0x117/0x270
[<ffffffff8a034357>] local_apic_timer_interrupt+0x37/0x60
[<ffffffff8a80010f>] smp_apic_timer_interrupt+0x3f/0x50
[<ffffffff8a7fe52f>] apic_timer_interrupt+0x6f/0x80
To fix this we force non-lazy irq works to run on irq work self-IPIs
when available. That ability of the arch to trigger irq work self IPIs
is available with arch_irq_work_has_interrupt().
Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Reported-by: Dave Jones <davej@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This way we unbloat a bit main.c and more importantly we initialize
nohz full after init_IRQ(). This dependency will be needed in further
patches because nohz full needs irq work to raise its own IRQ.
Information about the support for this ability on ARM64 is obtained on
init_IRQ() which initialize the pointer to __smp_call_function.
Since tick_init() is called right after init_IRQ(), this is a good place
to call tick_nohz_init() and prepare for that dependency.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Locks the k_itimer's it_lock member when handling the alarm timer's
expiry callback.
The regular posix timers defined in posix-timers.c have this lock held
during timout processing because their callbacks are routed through
posix_timer_fn(). The alarm timers follow a different path, so they
ought to grab the lock somewhere else.
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Avoids sending a signal to alarm timers created with sigev_notify set to
SIGEV_NONE by checking for that special case in the timeout callback.
The regular posix timers avoid sending signals to SIGEV_NONE timers by
not scheduling any callbacks for them in the first place. Although it
would be possible to do something similar for alarm timers, it's simpler
to handle this as a special case in the timeout.
Prior to this patch, the alarm timer would ignore the sigev_notify value
and try to deliver signals to the process anyway. Even worse, the
sanity check for the value of sigev_signo is skipped when SIGEV_NONE was
specified, so the signal number could be bogus. If sigev_signo was an
unitialized value (as it often would be if SIGEV_NONE is used), then
it's hard to predict which signal will be sent.
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Returns the time remaining for an alarm timer, rather than the time at
which it is scheduled to expire. If the timer has already expired or it
is not currently scheduled, the it_value's members are set to zero.
This new behavior matches that of the other posix-timers and the POSIX
specifications.
This is a change in user-visible behavior, and may break existing
applications. Hopefully, few users rely on the old incorrect behavior.
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
[jstultz: minor style tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:
setitimer(ITIMER_PROF, &val, NULL);
setitimer(ITIMER_PROF, NULL, &val);
would add a full tick to val, _even if it was exactly representable in
terms of jiffies_ (say, the result of a previous rounding.) Doing
this repeatedly would cause unbounded growth in val. So fix the math.
Here's what was wrong with the conversion: we essentially computed
(eliding seconds)
jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:
jiffies = (usec * x) >> USEC_JIFFIE_SC
and rounded this calculation up in the intermediate form (since we
can't necessarily exactly represent TICK_NSEC in usec.) But the
scaling arithmetic is a (very slight) *over*approximation of the true
value; that is, instead of dividing by (1 usec/ 1 jiffie), we
effectively divided by (1 usec/1 jiffie)-epsilon (rounding
down). This would normally be fine, but we want to round timeouts up,
and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this
would be fine if our division was exact, but dividing this by the
slightly smaller factor was equivalent to adding just _over_ 1 to the
final result (instead of just _under_ 1, as desired.)
In particular, with HZ=1000, we consistently computed that 10000 usec
was 11 jiffies; the same was true for any exact multiple of
TICK_NSEC.
We could possibly still round in the intermediate form, adding
something less than 2^USEC_JIFFIE_SC - 1, but easier still is to
convert usec->nsec, round in nanoseconds, and then convert using
time*spec*_to_jiffies. This adds one constant multiplication, and is
not observably slower in microbenchmarks on recent x86 hardware.
Tested: the following program:
int main() {
struct itimerval zero = {{0, 0}, {0, 0}};
/* Initially set to 10 ms. */
struct itimerval initial = zero;
initial.it_interval.tv_usec = 10000;
setitimer(ITIMER_PROF, &initial, NULL);
/* Save and restore several times. */
for (size_t i = 0; i < 10; ++i) {
struct itimerval prev;
setitimer(ITIMER_PROF, &zero, &prev);
/* on old kernels, this goes up by TICK_USEC every iteration */
printf("previous value: %ld %ld %ld %ld\n",
prev.it_interval.tv_sec, prev.it_interval.tv_usec,
prev.it_value.tv_sec, prev.it_value.tv_usec);
setitimer(ITIMER_PROF, &prev, NULL);
}
return 0;
}
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Paul Turner <pjt@google.com>
Reported-by: Aaron Jacobs <jacobsa@google.com>
Signed-off-by: Andrew Hunter <ahh@google.com>
[jstultz: Tweaked to apply to 3.17-rc]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Both times() and clock_gettime(CLOCK_PROCESS_CPUTIME_ID) have scalability
issues on large systems, due to both functions being serialized with a
lock.
The lock protects against reporting a wrong value, due to a thread in the
task group exiting, its statistics reporting up to the signal struct, and
that exited task's statistics being counted twice (or not at all).
Protecting that with a lock results in times() and clock_gettime() being
completely serialized on large systems.
This can be fixed by using a seqlock around the events that gather and
propagate statistics. As an additional benefit, the protection code can
be moved into thread_group_cputime(), slightly simplifying the calling
functions.
In the case of posix_cpu_clock_get_task() things can be simplified a
lot, because the calling function already ensures that the task sticks
around, and the rest is now taken care of in thread_group_cputime().
This way the statistics reporting code can run lockless.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guillaume Morin <guillaume@morinfr.org>
Cc: Ionut Alexa <ionut.m.alexa@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Link: http://lkml.kernel.org/r/20140816134010.26a9b572@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The update_walltime() code works on the shadow timekeeper to make the
seqcount protected region as short as possible. But that update to the
shadow timekeeper does not update all timekeeper fields because it's
sufficient to do that once before it becomes life. One of these fields
is tkr.base_mono. That stays stale in the shadow timekeeper unless an
operation happens which copies the real timekeeper to the shadow.
The update function is called after the update calls to vsyscall and
pvclock. While not correct, it did not cause any problems because none
of the invoked update functions used base_mono.
commit cbcf2dd3b3 (x86: kvm: Make kvm_get_time_and_clockread()
nanoseconds based) changed that in the kvm pvclock update function, so
the stale mono_base value got used and caused kvm-clock to malfunction.
Put the update where it belongs and fix the issue.
Reported-by: Chris J Arges <chris.j.arges@canonical.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409050000570.3333@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The local nohz kick is currently used by perf which needs it to be
NMI-safe. Recent commit though (7d1311b93e)
changed its implementation to fire the local kick using the remote kick
API. It was convenient to make the code more generic but the remote kick
isn't NMI-safe.
As a result:
WARNING: CPU: 3 PID: 18062 at kernel/irq_work.c:72 irq_work_queue_on+0x11e/0x140()
CPU: 3 PID: 18062 Comm: trinity-subchil Not tainted 3.16.0+ #34
0000000000000009 00000000903774d1 ffff880244e06c00 ffffffff9a7f1e37
0000000000000000 ffff880244e06c38 ffffffff9a0791dd ffff880244fce180
0000000000000003 ffff880244e06d58 ffff880244e06ef8 0000000000000000
Call Trace:
<NMI> [<ffffffff9a7f1e37>] dump_stack+0x4e/0x7a
[<ffffffff9a0791dd>] warn_slowpath_common+0x7d/0xa0
[<ffffffff9a07930a>] warn_slowpath_null+0x1a/0x20
[<ffffffff9a17ca1e>] irq_work_queue_on+0x11e/0x140
[<ffffffff9a10a2c7>] tick_nohz_full_kick_cpu+0x57/0x90
[<ffffffff9a186cd5>] __perf_event_overflow+0x275/0x350
[<ffffffff9a184f80>] ? perf_event_task_disable+0xa0/0xa0
[<ffffffff9a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
[<ffffffff9a187934>] perf_event_overflow+0x14/0x20
[<ffffffff9a020386>] intel_pmu_handle_irq+0x206/0x410
[<ffffffff9a0b54d3>] ? arch_vtime_task_switch+0x63/0x130
[<ffffffff9a01937b>] perf_event_nmi_handler+0x2b/0x50
[<ffffffff9a007b72>] nmi_handle+0xd2/0x390
[<ffffffff9a007aa5>] ? nmi_handle+0x5/0x390
[<ffffffff9a0d131b>] ? lock_release+0xab/0x330
[<ffffffff9a008062>] default_do_nmi+0x72/0x1c0
[<ffffffff9a0c925f>] ? cpuacct_account_field+0xcf/0x200
[<ffffffff9a008268>] do_nmi+0xb8/0x100
Lets fix this by restoring the use of local irq work for the nohz local
kick.
Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Reported-and-tested-by: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Convert all uses of __get_cpu_var for address calculation to use
this_cpu_ptr instead.
[Uses of __get_cpu_var with cpumask_var_t are no longer
handled by this patch]
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Convert uses of __get_cpu_var for creating a address from a percpu
offset to this_cpu_ptr.
The two cases where get_cpu_var is used to actually access a percpu
variable are changed to use this_cpu_read/raw_cpu_read.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In highres mode, the tick reschedules itself unconditionally to the
next jiffies.
However while this clock reprogramming is relevant when the tick is
in periodic mode, it's not that interesting when we run in dynticks mode
because irq exit is likely going to overwrite the next tick to some
randomly deferred future.
So lets just get rid of this tick self rescheduling in dynticks mode.
This way we can avoid some clockevents double write in favourable
scenarios like when we stop the tick completely in idle while no other
hrtimer is pending.
Suggested-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
When we reach the end of the tick handler, we unconditionally reschedule
the next tick to the next jiffy. Then on irq exit, the nohz code
overrides that setting if needed and defers the next tick as far away in
the future as possible.
Now in the best dynticks case, when we actually don't need any tick in
the future (ie: expires == KTIME_MAX), low-res and high-res behave
differently. What we want in this case is to cancel the next tick
programmed by the previous one. That's what we do in high-res mode. OTOH
we lack a low-res mode equivalent of hrtimer_cancel() so we simply don't
do anything in this case and the next tick remains scheduled to jiffies + 1.
As a result, in low-res mode, when the dynticks code determines that no
tick is needed in the future, we can recursively get a spurious tick
every jiffy because then the next tick is always reprogrammed from the
tick handler and is never cancelled. And this can happen indefinetly
until some subsystem actually needs a precise tick in the future and only
then we eventually overwrite the previous tick handler setting to defer
the next tick.
We are fixing this by introducing the ONESHOT_STOPPED mode which will
let us pause a clockevent when no further interrupt is needed. Meanwhile
we can't expect all drivers to support this new mode.
So lets reduce much of the symptoms by skipping the nohz-blind tick
rescheduling from the tick-handler when the CPU is in dynticks mode.
That tick rescheduling wrongly assumed periodicity and the low-res
dynticks code can't cancel such decision. This breaks the recursive (and
thus the worst) part of the problem. In the worst case now, we'll get
only one extra tick due to uncancelled tick scheduled before we entered
dynticks mode.
This also removes a needless clockevent write on idle ticks. Since those
clock write are usually considered to be slow, it's a general win.
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Benjamin Herrenschmidt pointed out that I further missed modifying
update_vsyscall after the wall_to_mono value was changed to a
timespec64. This causes issues on powerpc32, which expects a 32bit
timespec.
This patch fixes the problem by properly converting from a timespec64 to
a timespec before passing the value on to the arch-specific vsyscall
logic.
[ Thomas is currently on vacation, but reviewed it and wanted me to send
this fix on to you directly. ]
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull timer and time updates from Thomas Gleixner:
"A rather large update of timers, timekeeping & co
- Core timekeeping code is year-2038 safe now for 32bit machines.
Now we just need to fix all in kernel users and the gazillion of
user space interfaces which rely on timespec/timeval :)
- Better cache layout for the timekeeping internal data structures.
- Proper nanosecond based interfaces for in kernel users.
- Tree wide cleanup of code which wants nanoseconds but does hoops
and loops to convert back and forth from timespecs. Some of it
definitely belongs into the ugly code museum.
- Consolidation of the timekeeping interface zoo.
- A fast NMI safe accessor to clock monotonic for tracing. This is a
long standing request to support correlated user/kernel space
traces. With proper NTP frequency correction it's also suitable
for correlation of traces accross separate machines.
- Checkpoint/restart support for timerfd.
- A few NOHZ[_FULL] improvements in the [hr]timer code.
- Code move from kernel to kernel/time of all time* related code.
- New clocksource/event drivers from the ARM universe. I'm really
impressed that despite an architected timer in the newer chips SoC
manufacturers insist on inventing new and differently broken SoC
specific timers.
[ Ed. "Impressed"? I don't think that word means what you think it means ]
- Another round of code move from arch to drivers. Looks like most
of the legacy mess in ARM regarding timers is sorted out except for
a few obnoxious strongholds.
- The usual updates and fixlets all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits)
timekeeping: Fixup typo in update_vsyscall_old definition
clocksource: document some basic timekeeping concepts
timekeeping: Use cached ntp_tick_length when accumulating error
timekeeping: Rework frequency adjustments to work better w/ nohz
timekeeping: Minor fixup for timespec64->timespec assignment
ftrace: Provide trace clocks monotonic
timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC
seqcount: Add raw_write_seqcount_latch()
seqcount: Provide raw_read_seqcount()
timekeeping: Use tk_read_base as argument for timekeeping_get_ns()
timekeeping: Create struct tk_read_base and use it in struct timekeeper
timekeeping: Restructure the timekeeper some more
clocksource: Get rid of cycle_last
clocksource: Move cycle_last validation to core code
clocksource: Make delta calculation a function
wireless: ath9k: Get rid of timespec conversions
drm: vmwgfx: Use nsec based interfaces
drm: i915: Use nsec based interfaces
timekeeping: Provide ktime_get_raw()
hangcheck-timer: Use ktime_get_ns()
...
Here's the big pull request for the staging driver tree for 3.17-rc1.
Lots of things in here, over 2000 patches, but the best part is this:
1480 files changed, 39070 insertions(+), 254659 deletions(-)
Thanks to the great work of Kristina Martšenko, 14 different staging
drivers have been removed from the tree as they were obsolete and no one
was willing to work on cleaning them up. Other than the driver
removals, loads of cleanups are in here (comedi, lustre, etc.) as well
as the usual IIO driver updates and additions.
All of this has been in the linux-next tree for a while.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging driver updates from Greg KH:
"Here's the big pull request for the staging driver tree for 3.17-rc1.
Lots of things in here, over 2000 patches, but the best part is this:
1480 files changed, 39070 insertions(+), 254659 deletions(-)
Thanks to the great work of Kristina Martšenko, 14 different staging
drivers have been removed from the tree as they were obsolete and no
one was willing to work on cleaning them up. Other than the driver
removals, loads of cleanups are in here (comedi, lustre, etc.) as well
as the usual IIO driver updates and additions.
All of this has been in the linux-next tree for a while"
* tag 'staging-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (2199 commits)
staging: comedi: addi_apci_1564: remove diagnostic interrupt support code
staging: comedi: addi_apci_1564: add subdevice to check diagnostic status
staging: wlan-ng: coding style problem fix
staging: wlan-ng: fixing coding style problems
staging: comedi: ii_pci20kc: request and ioremap memory
staging: lustre: bitwise vs logical typo
staging: dgnc: Remove unneeded dgnc_trace.c and dgnc_trace.h
staging: dgnc: rephrase comment
staging: comedi: ni_tio: remove some dead code
staging: rtl8723au: Fix static symbol sparse warning
staging: rtl8723au: usb_dvobj_init(): Remove unused variable 'pdev_desc'
staging: rtl8723au: Do not duplicate kernel provided USB macros
staging: rtl8723au: Remove never set struct pwrctrl_priv.bHWPowerdown
staging: rtl8723au: Remove two never set variables
staging: rtl8723au: RSSI_test is never set
staging:r8190: coding style: Fixed checkpatch reported Error
staging:r8180: coding style: Fixed too long lines
staging:r8180: coding style: Fixed commenting style
staging: lustre: ptlrpc: lproc_ptlrpc.c - fix dereferenceing user space buffer
staging: lustre: ldlm: ldlm_resource.c - fix dereferenceing user space buffer
...
Pull scheduler updates from Ingo Molnar:
- Move the nohz kick code out of the scheduler tick to a dedicated IPI,
from Frederic Weisbecker.
This necessiated quite some background infrastructure rework,
including:
* Clean up some irq-work internals
* Implement remote irq-work
* Implement nohz kick on top of remote irq-work
* Move full dynticks timer enqueue notification to new kick
* Move multi-task notification to new kick
* Remove unecessary barriers on multi-task notification
- Remove proliferation of wait_on_bit() action functions and allow
wait_on_bit_action() functions to support a timeout. (Neil Brown)
- Another round of sched/numa improvements, cleanups and fixes. (Rik
van Riel)
- Implement fast idling of CPUs when the system is partially loaded,
for better scalability. (Tim Chen)
- Restructure and fix the CPU hotplug handling code that may leave
cfs_rq and rt_rq's throttled when tasks are migrated away from a dead
cpu. (Kirill Tkhai)
- Robustify the sched topology setup code. (Peterz Zijlstra)
- Improve sched_feat() handling wrt. static_keys (Jason Baron)
- Misc fixes.
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
sched/fair: Fix 'make xmldocs' warning caused by missing description
sched: Use macro for magic number of -1 for setparam
sched: Robustify topology setup
sched: Fix sched_setparam() policy == -1 logic
sched: Allow wait_on_bit_action() functions to support a timeout
sched: Remove proliferation of wait_on_bit() action functions
sched/numa: Revert "Use effective_load() to balance NUMA loads"
sched: Fix static_key race with sched_feat()
sched: Remove extra static_key*() function indirection
sched/rt: Fix replenish_dl_entity() comments to match the current upstream code
sched: Transform resched_task() into resched_curr()
sched/deadline: Kill task_struct->pi_top_task
sched: Rework check_for_tasks()
sched/rt: Enqueue just unthrottled rt_rq back on the stack in __disable_runtime()
sched/fair: Disable runtime_enabled on dying rq
sched/numa: Change scan period code to match intent
sched/numa: Rework best node setting in task_numa_migrate()
sched/numa: Examine a task move when examining a task swap
sched/numa: Simplify task_numa_compare()
sched/numa: Use effective_load() to balance NUMA loads
...
Pull RCU changes from Ingo Molar:
"The main changes:
- torture-test updates
- callback-offloading changes
- maintainership changes
- update RCU documentation
- miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
rcu: Allow for NULL tick_nohz_full_mask when nohz_full= missing
rcu: Fix a sparse warning in rcu_report_unblock_qs_rnp()
rcu: Fix a sparse warning in rcu_initiate_boost()
rcu: Fix __rcu_reclaim() to use true/false for bool
rcu: Remove CONFIG_PROVE_RCU_DELAY
rcu: Use __this_cpu_read() instead of per_cpu_ptr()
rcu: Don't use NMIs to dump other CPUs' stacks
rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs
rcu: Simplify priority boosting by putting rt_mutex in rcu_node
rcu: Check both root and current rcu_node when setting up future grace period
rcu: Allow post-unlock reference for rt_mutex
rcu: Loosen __call_rcu()'s rcu_head alignment constraint
rcu: Eliminate read-modify-write ACCESS_ONCE() calls
rcu: Remove redundant ACCESS_ONCE() from tick_do_timer_cpu
rcu: Make rcu node arrays static const char * const
signal: Explain local_irq_save() call
rcu: Handle obsolete references to TINY_PREEMPT_RCU
rcu: Document deadlock-avoidance information for rcu_read_unlock()
scripts: Teach get_maintainer.pl about the new "R:" tag
rcu: Update rcu torture maintainership filename patterns
...
During suspend we call sched_clock_poll() to update the epoch and
accumulated time and reprogram the sched_clock_timer to fire
before the next wrap-around time. Unfortunately,
sched_clock_poll() doesn't restart the timer, instead it relies
on the hrtimer layer to do that and during suspend we aren't
calling that function from the hrtimer layer. Instead, we're
reprogramming the expires time while the hrtimer is enqueued,
which can cause the hrtimer tree to be corrupted. Furthermore, we
restart the timer during suspend but we update the epoch during
resume which seems counter-intuitive.
Let's fix this by saving the accumulated state and canceling the
timer during suspend. On resume we can update the epoch and
restart the timer similar to what we would do if we were starting
the clock for the first time.
Fixes: a08ca5d108 "sched_clock: Use an hrtimer instead of timer"
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1406174630-23458-1-git-send-email-john.stultz@linaro.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
By caching the ntp_tick_length() when we correct the frequency error,
and then using that cached value to accumulate error, we avoid large
initial errors when the tick length is changed.
This makes convergence happen much faster in the simulator, since the
initial error doesn't have to be slowly whittled away.
This initially seems like an accounting error, but Miroslav pointed out
that ntp_tick_length() can change mid-tick, so when we apply it in the
error accumulation, we are applying any recent change to the entire tick.
This approach chooses to apply changes in the ntp_tick_length() only to
the next tick, which allows us to calculate the freq correction before
using the new tick length, which avoids accummulating error.
Credit to Miroslav for pointing this out and providing the original patch
this functionality has been pulled out from, along with the rational.
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reported-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The existing timekeeping_adjust logic has always been complicated
to understand. Further, since it was developed prior to NOHZ becoming
common, its not surprising it performs poorly when NOHZ is enabled.
Since Miroslav pointed out the problematic nature of the existing code
in the NOHZ case, I've tried to refactor the code to perform better.
The problem with the previous approach was that it tried to adjust
for the total cumulative error using a scaled dampening factor. This
resulted in large errors to be corrected slowly, while small errors
were corrected quickly. With NOHZ the timekeeping code doesn't know
how far out the next tick will be, so this results in bad
over-correction to small errors, and insufficient correction to large
errors.
Inspired by Miroslav's patch, I've refactored the code to try to
address the correction in two steps.
1) Check the future freq error for the next tick, and if the frequency
error is large, try to make sure we correct it so it doesn't cause
much accumulated error.
2) Then make a small single unit adjustment to correct any cumulative
error that has collected over time.
This method performs fairly well in the simulator Miroslav created.
Major credit to Miroslav for pointing out the issue, providing the
original patch to resolve this, a simulator for testing, as well as
helping debug and resolve issues in my implementation so that it
performed closer to his original implementation.
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reported-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In the GENERIC_TIME_VSYSCALL_OLD update_vsyscall implementation,
we take the tk_xtime() value, which returns a timespec64, and
store it in a timespec.
This luckily is ok, since the only architectures that use
GENERIC_TIME_VSYSCALL_OLD are ia64 and ppc64, which are both
64 bit systems where timespec64 is the same as a timespec.
Even so, for cleanliness reasons, use the conversion function
to assign the proper type.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tracers want a correlated time between the kernel instrumentation and
user space. We really do not want to export sched_clock() to user
space, so we need to provide something sensible for this.
Using separate data structures with an non blocking sequence count
based update mechanism allows us to do that. The data structure
required for the readout has a sequence counter and two copies of the
timekeeping data.
On the update side:
smp_wmb();
tkf->seq++;
smp_wmb();
update(tkf->base[0], tk);
smp_wmb();
tkf->seq++;
smp_wmb();
update(tkf->base[1], tk);
On the reader side:
do {
seq = tkf->seq;
smp_rmb();
idx = seq & 0x01;
now = now(tkf->base[idx]);
smp_rmb();
} while (seq != tkf->seq)
So if a NMI hits the update of base[0] it will use base[1] which is
still consistent, but this timestamp is not guaranteed to be monotonic
across an update.
The timestamp is calculated by:
now = base_mono + clock_delta * slope
So if the update lowers the slope, readers who are forced to the
not yet updated second array are still using the old steeper slope.
tmono
^
| o n
| o n
| u
| o
|o
|12345678---> reader order
o = old slope
u = update
n = new slope
So reader 6 will observe time going backwards versus reader 5.
While other CPUs are likely to be able observe that, the only way
for a CPU local observation is when an NMI hits in the middle of
the update. Timestamps taken from that NMI context might be ahead
of the following timestamps. Callers need to be aware of that and
deal with it.
V2: Got rid of clock monotonic raw and reorganized the data
structures. Folded in the barrier fix from Mathieu.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
All the function needs is in the tk_read_base struct. No functional
change for the current code, just a preparatory patch for the NMI safe
accessor to clock monotonic which will use struct tk_read_base as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The members of the new struct are the required ones for the new NMI
safe accessor to clcok monotonic. In order to reuse the existing
timekeeping code and to make the update of the fast NMI safe
timekeepers a simple memcpy use the struct for the timekeeper as well
and convert all users.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Access to time requires to touch two cachelines at minimum
1) The timekeeper data structure
2) The clocksource data structure
The access to the clocksource data structure can be avoided as almost
all clocksource implementations ignore the argument to the read
callback, which is a pointer to the clocksource.
But the core needs to touch it to access the members @read and @mask.
So we are better off by copying the @read function pointer and the
@mask from the clocksource to the core data structure itself.
For the most used ktime_get() access all required data including the
@read and @mask copies fits together with the sequence counter into a
single 64 byte cacheline.
For the other time access functions we touch in the current code three
cache lines in the worst case. But with the clocksource data copies we
can reduce that to two adjacent cachelines, which is more efficient
than disjunct cache lines.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
cycle_last was added to the clocksource to support the TSC
validation. We moved that to the core code, so we can get rid of the
extra copy.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The only user of the cycle_last validation is the x86 TSC. In order to
provide NMI safe accessor functions for clock monotonic and
monotonic_raw we need to do that in the core.
We can't do the TSC specific
if (now < cycle_last)
now = cycle_last;
for the other wrapping around clocksources, but TSC has
CLOCKSOURCE_MASK(64) which actually does not mask out anything so if
now is less than cycle_last the subtraction will give a negative
result. So we can check for that in clocksource_delta() and return 0
for that case.
Implement and enable it for x86
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
We want to move the TSC sanity check into core code to make NMI safe
accessors to clock monotonic[_raw] possible. For this we need to
sanity check the delta calculation. Create a helper function and
convert all sites to use it.
[ Build fix from jstultz ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Provide a ktime_t based interface for raw monotonic time.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
timekeeping_clocktai() is not used in fast pathes, so the extra
timespec conversion is not problematic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Subtracting plain nsec values and converting to timespec is simpler
than the whole timespec math. Not really fastpath code, so the
division is not an issue.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
get_monotonic_boottime() is not used in fast pathes, so the extra
timespec conversion is not problematic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Required for moving drivers to the nanosecond based interfaces.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
ktime based conversion function to map a monotonic time stamp to a
different CLOCK.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Provide a helper function which lets us implement ktime_t based
interfaces for real, boot and tai clocks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Speed up ktime_get() by using ktime_t based data. Text size shrinks by
64 bytes on x8664.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The ktime_t based interfaces are used a lot in performance critical
code pathes. Add ktime_t based data so the interfaces don't have to
convert from the xtime/timespec based data.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
We already have a function which does the right thing, that also makes
sure that the coming ktime_t based cached values are getting updated.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
struct timekeeper is quite badly sorted for the hot readout path. Most
time access functions need to load two cache lines.
Rearrange it so ktime_get() and getnstimeofday() are happy with a
single cache line.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
To convert callers of the core code to timespec64 we need to provide
the proper interfaces.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Right now we have time related prototypes in 3 different header
files. Move it to a single timekeeping header file and move the core
internal stuff into a core private header.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Convert the core timekeeping logic to use timespec64s. This moves the
2038 issues out of the core logic and into all of the accessor
functions.
Future changes will need to push the timespec64s out to all
timekeeping users, but that can be done interface by interface.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Helper and conversion functions for timespec64.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
With the plain nanoseconds based ktime_t we can simply use
ktime_divns() instead of going through loops and hoops of
timespec/timeval conversion.
Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The non-scalar ktime_t implementation is basically a timespec
which has to be changed to support dates past 2038 on 32bit
systems.
This patch removes the non-scalar ktime_t implementation, forcing
the scalar s64 nanosecond version on all architectures.
This may have additional performance overhead on some 32bit
systems when converting between ktime_t and timespec structures,
however the majority of 32bit systems (arm and i386) were already
using scalar ktime_t, so no performance regressions will be seen
on those platforms.
On affected platforms, I'm open to finding optimizations, including
avoiding converting to timespecs where possible.
[ tglx: We can now cleanup the ktime_t.tv64 mess, but thats a
different issue and we can throw a coccinelle script at it ]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Rather then having two similar but totally different implementations
that provide timekeeping state to the hrtimer code, try to unify the
two implementations to be more simliar.
Thus this clarifies ktime_get_update_offsets to
ktime_get_update_offsets_now and changes get_xtime... to
ktime_get_update_offsets_tick.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Provide a default stub function instead of having the extra
conditional. Cuts binary size on a m68k build by ~100 bytes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Create a module that allows udelay() to be executed to ensure that
it is delaying at least as long as requested (with a little bit of
error allowed).
There are some configurations which don't have reliably udelay
due to using a loop delay with cpufreq changes which should use
a counter time based delay instead. This test aims to identify
those configurations where timing is unreliable.
Signed-off-by: David Riley <davidriley@chromium.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Binding the grace-period kthreads to the timekeeping CPU resulted in
significant performance decreases for some workloads. For more detail,
see:
https://lkml.org/lkml/2014/6/3/395 for benchmark numbers
https://lkml.org/lkml/2014/6/4/218 for CPU statistics
It turns out that it is necessary to bind the grace-period kthreads
to the timekeeping CPU only when all but CPU 0 is a nohz_full CPU
on the one hand or if CONFIG_NO_HZ_FULL_SYSIDLE=y on the other.
In other cases, it suffices to bind the grace-period kthreads to the
set of non-nohz_full CPUs.
This commit therefore creates a tick_nohz_not_full_mask that is the
complement of tick_nohz_full_mask, and then binds the grace-period
kthread to the set of CPUs indicated by this new mask, which covers
the CONFIG_NO_HZ_FULL_SYSIDLE=n case. The CONFIG_NO_HZ_FULL_SYSIDLE=y
case still binds the grace-period kthreads to the timekeeping CPU.
This commit also includes the tick_nohz_full_enabled() check suggested
by Frederic Weisbecker.
Reported-by: Jet Chen <jet.chen@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Created housekeeping_affine() and housekeeping_mask per
fweisbec feedback. ]
Sharvil noticed with the posix timer_settime interface, using the
CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users
tried to specify a relative time timer, it would incorrectly be
treated as absolute regardless of the state of the flags argument.
This patch corrects this, properly checking the absolute/relative flag,
as well as adds further error checking that no invalid flag bits are set.
Reported-by: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Cc: stable <stable@vger.kernel.org> #3.0+
Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We call hrtimer_enqueue_reprogram() only when we are in high resolution
mode now so we don't need to check that again in hrtimer_enqueue_reprogram().
Once the check is removed, hrtimer_enqueue_reprogram() turns to be an
useless wrapper over hrtimer_reprogram() and can be dropped.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In lowres mode, hrtimers are serviced by the tick instead of a clock
event. It works well as long as the tick stays periodic but we must also
make sure that the hrtimers are serviced in dynticks mode targets,
pretty much like timer list timers do.
Note that all dynticks modes are concerned: get_nohz_timer_target()
tries not to return remote idle CPUs but there is nothing to prevent
the elected target from entering dynticks idle mode until we lock its
base. It's also prefectly legal to enqueue hrtimers on full dynticks CPU.
So there are two requirements to correctly handle dynticks:
1) On target's tick stop time, we must not delay the next tick further
the next hrtimer.
2) On hrtimer queue time. If the tick of the target is stopped, we must
wake up that CPU such that it sees the new hrtimer and recalculate
the next tick accordingly.
The point 1 is well handled currently through get_nohz_timer_interrupt() and
cmp_next_hrtimer_event().
But the point 2 isn't handled at all.
Fixing this is easy though as we have the necessary API ready for that.
All we need is to call wake_up_nohz_cpu() on a target when a newly
enqueued hrtimer requires tick rescheduling, like timer list timer do.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/3d7ea08ce008698e26bd39fe10f55949391073ab.1403507178.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In lowres mode, hrtimers are serviced by the tick instead of a clock
event. Now it works well as long as the tick stays periodic but we
must also make sure that the hrtimers are serviced in dynticks mode.
Part of that job consist in kicking a dynticks hrtimer target in order
to make it reconsider the next tick to schedule to correctly handle the
hrtimer's expiring time. And that part isn't handled by the hrtimers
subsystem.
To prepare for fixing this, we need __hrtimer_start_range_ns() to be
able to resolve the CPU target associated to a hrtimer's object
'cpu_base' so that the kick can be centralized there.
So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU
without overhead. It is set once at CPU's online notification.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When a timer is enqueued or modified on a dynticks target, that CPU
must re-evaluate the next tick to service that timer.
The tick re-evaluation is performed by an IPI kick on the target.
Now while we correctly call wake_up_nohz_cpu() from add_timer_on(), the
mod_timer*() API family doesn't support so well dynticks targets.
The reason for this is likely that __mod_timer() isn't supposed to
select an idle target for a timer, unless that target is the current
CPU, in which case a dynticks idle kick isn't actually needed.
But there is a small race window lurking behind that assumption: the
elected target has all the time to turn dynticks idle between the call
to get_nohz_timer_target() and the locking of its base. Hence a risk
that we enqueue a timer on a dynticks idle destination without kicking
it. As a result, the timer might be serviced too late in the future.
Also a target elected by __mod_timer() can be in full dynticks mode
and thus require to be kicked as well. And unlike idle dynticks, this
concern both local and remote targets.
To fix this whole issue, lets centralize the dynticks kick to
internal_add_timer() so that it is well handled for all sort of timer
enqueue. Even timer migration is concerned so that a full dynticks target
is correctly kicked as needed when timers are migrating to it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Timers are serviced by the tick. But when a timer is enqueued on a
dynticks target, we need to kick it in order to make it reconsider the
next tick to schedule to correctly handle the timer's expiring time.
Now while this kick is correctly performed for add_timer_on(), the
mod_timer*() family has been a bit neglected.
To prepare for fixing this, we need internal_add_timer() to be able to
resolve the CPU target associated to a timer's object 'base' so that the
kick can be centralized there.
This can't be passed as an argument as not all the callers know the CPU
number of a timer's base. So lets store it in the struct tvec_base to
resolve the CPU without much overhead. It is set once for good at every
CPU's first boot.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Export symbol of alarmtimer_get_rtcdev so that it is used by
any driver when built as module like,
drivers/staging/android/alarm-dev.c.
CC: John Stultz <john.stultz@linaro.org>
CC: Marcus Gelderie <redmnic@gmail.com>
Signed-off-by: Pramod Gurav <pramod.gurav.etc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remotely kicking a full nohz CPU in order to make it re-evaluate its
next tick is currently implemented using the scheduler IPI.
However this bloats a scheduler fast path with an off-topic feature.
The scheduler tick was abused here for its cool "callable
anywhere/anytime" properties.
But now that the irq work subsystem can queue remote callbacks, it's
a perfect fit to safely queue IPIs when interrupts are disabled
without worrying about concurrent callers.
So lets implement remote kick on top of irq work. This is going to
be used when a new event requires the next tick to be recalculated:
more than 1 task competing on the CPU, timer armed, ...
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Merge misc updates from Andrew Morton:
- a few fixes for 3.16. Cc'ed to stable so they'll get there somehow.
- various misc fixes and cleanups
- most of the ocfs2 queue. Review is slow...
- most of MM. The MM queue is pretty huge this time, but not much in
the way of feature work.
- some tweaks under kernel/
- printk maintenance work
- updates to lib/
- checkpatch updates
- tweaks to init/
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (276 commits)
fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init
fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul
init/main.c: remove an ifdef
kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND
init/main.c: add initcall_blacklist kernel parameter
init/main.c: don't use pr_debug()
fs/binfmt_flat.c: make old_reloc() static
fs/binfmt_elf.c: fix bool assignements
fs/efs: convert printk(KERN_DEBUG to pr_debug
fs/efs: add pr_fmt / use __func__
fs/efs: convert printk to pr_foo()
scripts/checkpatch.pl: device_initcall is not the only __initcall substitute
checkpatch: check stable email address
checkpatch: warn on unnecessary void function return statements
checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar);
checkpatch: add warning for kmalloc/kzalloc with multiply
checkpatch: warn on #defines ending in semicolon
checkpatch: make --strict a default for files in drivers/net and net/
checkpatch: always warn on missing blank line after variable declaration block
checkpatch: fix wildcard DT compatible string checking
...
Jiri Bohac pointed out that there are rare but potential deadlock
possibilities when calling printk while holding the timekeeping
seqlock.
This is due to printk() triggering console sem wakeup, which can
cause scheduling code to trigger hrtimers which may try to read
the time.
Specifically, as Jiri pointed out, that path is:
printk
vprintk_emit
console_unlock
up(&console_sem)
__up
wake_up_process
try_to_wake_up
ttwu_do_activate
ttwu_activate
activate_task
enqueue_task
enqueue_task_fair
hrtick_update
hrtick_start_fair
hrtick_start_fair
get_time
ktime_get
--> endless loop on
read_seqcount_retry(&timekeeper_seq, ...)
This patch tries to avoid this issue by using printk_deferred (previously
named printk_sched) which should defer printing via a irq_work_queue.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reported-by: Jiri Bohac <jbohac@suse.cz>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
is_error_status() is an inline function always called with the
global time_status as an argument, so there's zero functional
difference with this change, but the non-CONFIG_NTP_PPS version
uses the passed-in argument, while the CONFIG_NTP_PPS one ignores
its argument and uses the global.
Looks like is_error_status was refactored out, but someone forgot
to change the logic to check the local argument value.
Thus this patch makes it use the argument always; shorter variable
names are good.
Signed-off-by: George Spelvin <linux@horizon.com>
[jstultz: Tweaked commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Replace obsolete function simple_strtol w/ kstrtol
Inspired-By: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
[jstultz: Tweak commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Remove the 32-bit only setup_sched_clock() API now that all users
have been converted to the 64-bit friendly sched_clock_register().
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In tick_do_update_jiffies64() we are processing ticks only if delta is
greater than tick_period. This is what we are supposed to do here and
it broke a bit with this patch:
commit 47a1b796 (tick/timekeeping: Call update_wall_time outside the
jiffies lock)
With above patch, we might end up calling update_wall_time() even if
delta is found to be smaller that tick_period. Fix this by returning
when the delta is less than tick period.
[ tglx: Made it a 3 liner and massaged changelog ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: Arvind.Chauhan@arm.com
Cc: linaro-networking@linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Cc: <stable@vger.kernel.org> # v3.14+
Link: http://lkml.kernel.org/r/80afb18a494b0bd9710975bcc4de134ae323c74f.1397537987.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
To increase compiler portability there is <linux/compiler.h> which
provides convenience macros for various gcc constructs. Eg: __weak for
__attribute__((weak)). I've replaced all instances of gcc attributes
with the right macro in the kernel subsystem.
Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull timer changes from Thomas Gleixner:
"This assorted collection provides:
- A new timer based timer broadcast feature for systems which do not
provide a global accessible timer device. That allows those
systems to put CPUs into deep idle states where the per cpu timer
device stops.
- A few NOHZ_FULL related improvements to the timer wheel
- The usual updates to timer devices found in ARM SoCs
- Small improvements and updates all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
tick: Remove code duplication in tick_handle_periodic()
tick: Fix spelling mistake in tick_handle_periodic()
x86: hpet: Use proper destructor for delayed work
workqueue: Provide destroy_delayed_work_on_stack()
clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS
timer: Remove code redundancy while calling get_nohz_timer_target()
hrtimer: Rearrange comments in the order struct members are declared
timer: Use variable head instead of &work_list in __run_timers()
clocksource: exynos_mct: silence a static checker warning
arm: zynq: Add support for cpufreq
arm: zynq: Don't use arm_global_timer with cpufreq
clocksource/cadence_ttc: Overhaul clocksource frequency adjustment
clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs enabled
clocksource: Add Kconfig entries for CMT, MTU2, TMU and STI
sh: Remove Kconfig entries for TMU, CMT and MTU2
ARM: shmobile: Remove CMT, TMU and STI Kconfig entries
clocksource: armada-370-xp: Use atomic access for shared registers
clocksource: orion: Use atomic access for shared registers
clocksource: timer-keystone: Delete unnecessary variable
clocksource: timer-keystone: introduce clocksource driver for Keystone
...
In commit 47a1b79630 ("tick/timekeeping: Call
update_wall_time outside the jiffies lock"), we moved to calling
clock_was_set() due to the fact that we were no longer holding
the timekeeping or jiffies lock.
However, there is still the problem that clock_was_set()
triggers an IPI, which cannot be done from the timer's hard irq
context, and will generate WARN_ON warnings.
Apparently in my earlier testing, I'm guessing I didn't bump the
dmesg log level, so I somehow missed the WARN_ONs.
Thus we need to revert back to calling clock_was_set_delayed().
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1395963049-11923-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Include appropriate header file kernel/time/timekeeping_internal.h in
kernel/time/timekeeping_debug.c because it has prototype declaration of
function defined in kernel/time/timekeeping_debug.c.
This eliminates the following warning in
kernel/time/timekeeping_debug.c:
kernel/time/timekeeping_debug.c:68:6: warning: no previous prototype for ‘tk_debug_account_sleep_time’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The generic sched_clock registration function was previously
done lockless, due to the fact that it was expected to be called
only once. However, now there are systems that may register
multiple sched_clock sources, for which the lack of locking has
casued problems:
If two sched_clock sources are registered we may end up in a
situation where a call to sched_clock() may be accessing the
epoch cycle count for the old counter and the cycle count for the
new counter. This can lead to confusing results where
sched_clock() values jump and then are reset to 0 (due to the way
the registration function forces the epoch_ns to be 0).
Fix this by reorganizing the registration function to hold the
seqlock for as short a time as possible while we update the
clock_data structure for a new counter. We also put any
accumulated time into epoch_ns instead of resetting the time to
0 so that the clock doesn't reset after each successful
registration.
[jstultz: Added extra context to the commit message]
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This bit of information is in the Kconfig help text:
"Note the boot CPU will still be kept outside the range to
handle the timekeeping duty."
However neither the variable NO_HZ_FULL_ALL, or the prompt
convey this important detail, so lets add it to the prompt
to make it more explicitly obvious to the average user.
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1391711781-7466-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
AMD systems which use the C1E workaround in the amd_e400_idle routine
trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.
The reason is that the idle routine of those AMD systems switches the
cpu into forced broadcast mode early on before the newly brought up
CPU can switch over to high resolution / NOHZ mode. The timer related
CPU1 bringup looks like this:
clockevent_register_device(local_apic);
tick_setup(local_apic);
...
idle()
tick_broadcast_on_off(FORCE);
tick_broadcast_oneshot_control(ENTER)
cpumask_set(cpu, broadcast_oneshot_mask);
halt();
Now the broadcast interrupt on CPU0 sets CPU1 in the
broadcast_pending_mask and wakes CPU1. So CPU1 continues:
local_apic_timer_interrupt()
tick_handle_periodic();
softirq()
tick_init_highres();
cpumask_clr(cpu, broadcast_oneshot_mask);
tick_broadcast_oneshot_control(ENTER)
WARN_ON(cpumask_test(cpu, broadcast_pending_mask);
So while we remove CPU1 from the broadcast_oneshot_mask when we switch
over to highres mode, we do not clear the pending bit, which then
triggers the warning when we go back to idle.
The reason why this is only visible on C1E affected AMD systems is
that the other machines enter the deep sleep states via
acpi_idle/intel_idle and exit the broadcast mode before executing the
remote triggered local_apic_timer_interrupt. So the pending bit is
already cleared when the switch over to highres mode is clearing the
oneshot mask.
The solution is simple: Clear the pending bit together with the mask
bit when we switch over to highres mode.
Stanislaw came up independently with the same patch by enforcing the
C1E workaround and debugging the fallout. I picked mine, because mine
has a changelog :)
Reported-by: poma <pomidorabelisima@gmail.com>
Debugged-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Justin M. Forbes <jforbes@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The hrtimer mode of broadcast is supported only when
GENERIC_CLOCKEVENTS_BROADCAST and TICK_ONESHOT config options
are enabled. Hence compile in the functions for hrtimer mode
of broadcast only when these options are selected.
Also fix max_delta_ticks value for the pseudo clock device.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/52F719EE.9010304@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Make the stub function static inline instead of static and move the
clockevents related function into the proper ifdeffed section.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
On some architectures, in certain CPU deep idle states the local timers stop.
An external clock device is used to wakeup these CPUs. The kernel support for the
wakeup of these CPUs is provided by the tick broadcast framework by using the
external clock device as the wakeup source.
However not all implementations of architectures provide such an external
clock device. This patch includes support in the broadcast framework to handle
the wakeup of the CPUs in deep idle states on such systems by queuing a hrtimer
on one of the CPUs, which is meant to handle the wakeup of CPUs in deep idle states.
This patchset introduces a pseudo clock device which can be registered by the
archs as tick_broadcast_device in the absence of a real external clock
device. Once registered, the broadcast framework will work as is for these
architectures as long as the archs take care of the BROADCAST_ENTER
notification failing for one of the CPUs. This CPU is made the stand by CPU to
handle wakeup of the CPUs in deep idle and it *must not enter deep idle states*.
The CPU with the earliest wakeup is chosen to be this CPU. Hence this way the
stand by CPU dynamically moves around and so does the hrtimer which is queued
to trigger at the next earliest wakeup time. This is consistent with the case where
an external clock device is present. The smp affinity of this clock device is
set to the CPU with the earliest wakeup. This patchset handles the hotplug of
the stand by CPU as well by moving the hrtimer on to the CPU handling the CPU_DEAD
notification.
Originally-from: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080632.17187.80532.stgit@preeti.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
clockevent devices in periodic mode are not updated when the frequency
of the device changes. Issue a dev->set_mode() callback which forces
the device to reevaluate the timer settings.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-3-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
For better use of CPU idle time, allow the scheduler to select the CPU
on which the CMOS clock sync work would be scheduled. This improves
idle residency time and conserver power.
This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.
Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com>
[zoran.markovic@linaro.org: Added commit message. Aligned code.]
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull scheduler changes from Ingo Molnar:
- Add the initial implementation of SCHED_DEADLINE support: a real-time
scheduling policy where tasks that meet their deadlines and
periodically execute their instances in less than their runtime quota
see real-time scheduling and won't miss any of their deadlines.
Tasks that go over their quota get delayed (Available to privileged
users for now)
- Clean up and fix preempt_enable_no_resched() abuse all around the
tree
- Do sched_clock() performance optimizations on x86 and elsewhere
- Fix and improve auto-NUMA balancing
- Fix and clean up the idle loop
- Apply various cleanups and fixes
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
sched: Fix __sched_setscheduler() nice test
sched: Move SCHED_RESET_ON_FORK into attr::sched_flags
sched: Fix up attr::sched_priority warning
sched: Fix up scheduler syscall LTP fails
sched: Preserve the nice level over sched_setscheduler() and sched_setparam() calls
sched/core: Fix htmldocs warnings
sched/deadline: No need to check p if dl_se is valid
sched/deadline: Remove unused variables
sched/deadline: Fix sparse static warnings
m68k: Fix build warning in mac_via.h
sched, thermal: Clean up preempt_enable_no_resched() abuse
sched, net: Fixup busy_loop_us_clock()
sched, net: Clean up preempt_enable_no_resched() abuse
sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding
sched/preempt, locking: Rework local_bh_{dis,en}able()
sched/clock, x86: Avoid a runtime condition in native_sched_clock()
sched/clock: Fix up clear_sched_clock_stable()
sched/clock, x86: Use a static_key for sched_clock_stable
sched/clock: Remove local_irq_disable() from the clocks
sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs
...
Code usually starts with 'tab' instead of 7 'space' in kernel
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1386074112-30754-2-git-send-email-alex.shi@linaro.org
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
We don't need to fetch the timekeeping max deferment under the
jiffies_lock seqlock.
If the clocksource is updated concurrently while we stop the tick,
stop machine is called and the tick will be reevaluated again along with
uptodate jiffies and its related values.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-9-git-send-email-fweisbec@gmail.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This makes the code more symetric against the existing tick functions
called on irq exit: tick_irq_exit() and tick_nohz_irq_exit().
These function are also symetric as they mirror each other's action:
we start to account idle time on irq exit and we stop this accounting
on irq entry. Also the tick is stopped on irq exit and timekeeping
catches up with the tickless time elapsed until we reach irq entry.
This rename was suggested by Peter Zijlstra a long while ago but it
got forgotten in the mass.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Unfortunately the seqlock lockdep enablement can't be used
in sched_clock(), since the lockdep infrastructure eventually
calls into sched_clock(), which causes a deadlock.
Thus, this patch changes all generic sched_clock() usage
to use the raw_* methods.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Prior to 92bb1fcf57 (Only
do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD
systems), the comment here was accuate, but now we can
mostly avoid the extra rounding which causes the unlikey
to be actually likely here.
So remove the out of date comment.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Fix trivial comment typo for tk_setup_internals().
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since 48cdc135d4 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.
In the timekeeping suspend path, we udpate the timekeeper
structure, so we should be sure to update the shadow-timekeeper
before releasing the timekeeping locks. Currently this isn't done.
In most cases, the next time related code to run would be
timekeeping_resume, which does update the shadow-timekeeper, but
in an abundence of caution, this patch adds the call to
timekeeping_update() in the suspend path.
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
A think-o in the calculation of the monotonic -> tai time offset
results in CLOCK_TAI timers and nanosleeps to expire late (the
latency is ~2x the tai offset).
Fix this by adding the tai offset from the realtime offset instead
of subtracting.
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since the xtime lock was split into the timekeeping lock and
the jiffies lock, we no longer need to call update_wall_time()
while holding the jiffies lock.
Thus, this patch splits update_wall_time() out from do_timer().
This allows us to get away from calling clock_was_set_delayed()
in update_wall_time() and instead use the standard clock_was_set()
call that previously would deadlock, as it causes the jiffies lock
to be acquired.
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
As part of normal operaions, the hrtimer subsystem frequently calls
into the timekeeping code, creating a locking order of
hrtimer locks -> timekeeping locks
clock_was_set_delayed() was suppoed to allow us to avoid deadlocks
between the timekeeping the hrtimer subsystem, so that we could
notify the hrtimer subsytem the time had changed while holding
the timekeeping locks. This was done by scheduling delayed work
that would run later once we were out of the timekeeing code.
But unfortunately the lock chains are complex enoguh that in
scheduling delayed work, we end up eventually trying to grab
an hrtimer lock.
Sasha Levin noticed this in testing when the new seqlock lockdep
enablement triggered the following (somewhat abrieviated) message:
[ 251.100221] ======================================================
[ 251.100221] [ INFO: possible circular locking dependency detected ]
[ 251.100221] 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 Not tainted
[ 251.101967] -------------------------------------------------------
[ 251.101967] kworker/10:1/4506 is trying to acquire lock:
[ 251.101967] (timekeeper_seq){----..}, at: [<ffffffff81160e96>] retrigger_next_event+0x56/0x70
[ 251.101967]
[ 251.101967] but task is already holding lock:
[ 251.101967] (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[ 251.101967]
[ 251.101967] which lock already depends on the new lock.
[ 251.101967]
[ 251.101967]
[ 251.101967] the existing dependency chain (in reverse order) is:
[ 251.101967]
-> #5 (hrtimer_bases.lock#11){-.-...}:
[snipped]
-> #4 (&rt_b->rt_runtime_lock){-.-...}:
[snipped]
-> #3 (&rq->lock){-.-.-.}:
[snipped]
-> #2 (&p->pi_lock){-.-.-.}:
[snipped]
-> #1 (&(&pool->lock)->rlock){-.-...}:
[ 251.101967] [<ffffffff81194803>] validate_chain+0x6c3/0x7b0
[ 251.101967] [<ffffffff81194d9d>] __lock_acquire+0x4ad/0x580
[ 251.101967] [<ffffffff81194ff2>] lock_acquire+0x182/0x1d0
[ 251.101967] [<ffffffff84398500>] _raw_spin_lock+0x40/0x80
[ 251.101967] [<ffffffff81153e69>] __queue_work+0x1a9/0x3f0
[ 251.101967] [<ffffffff81154168>] queue_work_on+0x98/0x120
[ 251.101967] [<ffffffff81161351>] clock_was_set_delayed+0x21/0x30
[ 251.101967] [<ffffffff811c4bd1>] do_adjtimex+0x111/0x160
[ 251.101967] [<ffffffff811e2711>] compat_sys_adjtimex+0x41/0x70
[ 251.101967] [<ffffffff843a4b49>] ia32_sysret+0x0/0x5
[ 251.101967]
-> #0 (timekeeper_seq){----..}:
[snipped]
[ 251.101967] other info that might help us debug this:
[ 251.101967]
[ 251.101967] Chain exists of:
timekeeper_seq --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock#11
[ 251.101967] Possible unsafe locking scenario:
[ 251.101967]
[ 251.101967] CPU0 CPU1
[ 251.101967] ---- ----
[ 251.101967] lock(hrtimer_bases.lock#11);
[ 251.101967] lock(&rt_b->rt_runtime_lock);
[ 251.101967] lock(hrtimer_bases.lock#11);
[ 251.101967] lock(timekeeper_seq);
[ 251.101967]
[ 251.101967] *** DEADLOCK ***
[ 251.101967]
[ 251.101967] 3 locks held by kworker/10:1/4506:
[ 251.101967] #0: (events){.+.+.+}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[ 251.101967] #1: (hrtimer_work){+.+...}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[ 251.101967] #2: (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[ 251.101967]
[ 251.101967] stack backtrace:
[ 251.101967] CPU: 10 PID: 4506 Comm: kworker/10:1 Not tainted 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053
[ 251.101967] Workqueue: events clock_was_set_work
So the best solution is to avoid calling clock_was_set_delayed() while
holding the timekeeping lock, and instead using a flag variable to
decide if we should call clock_was_set() once we've released the locks.
This works for the case here, where the do_adjtimex() was the deadlock
trigger point. Unfortuantely, in update_wall_time() we still hold
the jiffies lock, which would deadlock with the ipi triggered by
clock_was_set(), preventing us from calling it even after we drop the
timekeeping lock. So instead call clock_was_set_delayed() at that point.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: stable <stable@vger.kernel.org> #3.10+
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In 780427f0e1 (Indicate that clock was set in the pvclock
gtod notifier), logic was added to pass a CLOCK_WAS_SET
notification to the pvclock notifier chain.
While that patch added a action flag returned from
accumulate_nsecs_to_secs(), it only uses the returned value
in one location, and not in the logarithmic accumulation.
This means if a leap second triggered during the logarithmic
accumulation (which is most likely where it would happen),
the notification that the clock was set would not make it to
the pv notifiers.
This patch extends the logarithmic_accumulation pass down
that action flag so proper notification will occur.
This patch also changes the varialbe action -> clock_set
per Ingo's suggestion.
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: <xen-devel@lists.xen.org>
Cc: stable <stable@vger.kernel.org> #3.11+
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since 48cdc135d4 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.
Unfortunately, the updates to the tai offset via adjtimex do not
trigger this update, causing adjustments to the tai offset to be
made and then over-written by the previous value at the next
update_wall_time() call.
This patch resovles the issue by calling timekeeping_update()
right after setting the tai offset.
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
A few functions use remote per CPU access APIs when they
deal with local values.
Just do the right conversion to improve performance, code
readability and debug checks.
While at it, lets extend some of these function names with *_this_cpu()
suffix in order to display their purpose more clearly.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ.
If CONFIG_NO_HZ=y and the nohz functionality is disabled via the
command line option "nohz=off" or not enabled due to missing hardware
support, then tick_nohz_get_sleep_length() returns 0. That happens
because ts->sleep_length is never set in that case.
Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive.
Reported-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since commit 1e75fa8be9 (time: Condense timekeeper.xtime
into xtime_sec - merged in v3.6), there has been an problem
with the error accounting in the timekeeping code, such that
when truncating to nanoseconds, we round up to the next nsec,
but the balancing adjustment to the ntp_error value was dropped.
This causes 1ns per tick drift forward of the clock.
In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD
architectures (s390, ia64, powerpc).
The fix is simply to balance the accounting and to subtract the
added nanosecond from ntp_error. This allows the internal long-term
clock steering to keep the clock accurate.
While this fix removes the regression added in 1e75fa8be9, the
ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD
and use the new VSYSCALL method, which avoids entirely the
nanosecond granular rounding, and the resulting short-term clock
adjustment oscillation needed to keep long term accurate time.
[ jstultz: Many thanks to Martin for his efforts identifying this
subtle bug, and providing the fix. ]
Originally-from: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable <stable@vger.kernel.org> #v3.6+
Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
RCU and the fine grained idle time accounting functions check
tick_nohz_enabled. But that variable is merily telling that NOHZ has
been enabled in the config and not been disabled on the command line.
But it does not tell anything about nohz being active. That's what all
this should check for.
Matthew reported, that the idle accounting on his old P1 machine
showed bogus values, when he enabled NOHZ in the config and did not
disable it on the kernel command line. The reason is that his machine
uses (refined) jiffies as a clocksource which explains why the "fine"
grained accounting went into lala land, because it depends on when the
system goes and leaves idle relative to the jiffies increment.
Provide a tick_nohz_active indicator and let RCU and the accounting
code use this instead of tick_nohz_enable.
Reported-and-tested-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: john.stultz@linaro.org
Cc: mwhitehe@redhat.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de
Pull timer changes from Ingo Molnar:
"Main changes in this cycle were:
- Updated full dynticks support.
- Event stream support for architected (ARM) timers.
- ARM clocksource driver updates.
- Move arm64 to using the generic sched_clock framework & resulting
cleanup in the generic sched_clock code.
- Misc fixes and cleanups"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
x86/time: Honor ACPI FADT flag indicating absence of a CMOS RTC
clocksource: sun4i: remove IRQF_DISABLED
clocksource: sun4i: Report the minimum tick that we can program
clocksource: sun4i: Select CLKSRC_MMIO
clocksource: Provide timekeeping for efm32 SoCs
clocksource: em_sti: convert to clk_prepare/unprepare
time: Fix signedness bug in sysfs_get_uname() and its callers
timekeeping: Fix some trivial typos in comments
alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist
clocksource: arch_timer: Do not register arch_sys_counter twice
timer stats: Add a 'Collection: active/inactive' line to timer usage statistics
sched_clock: Remove sched_clock_func() hook
arch_timer: Move to generic sched_clock framework
clocksource: tcb_clksrc: Remove IRQF_DISABLED
clocksource: tcb_clksrc: Improve driver robustness
clocksource: tcb_clksrc: Replace clk_enable/disable with clk_prepare_enable/disable_unprepare
clocksource: arm_arch_timer: Use clocksource for suspend timekeeping
clocksource: dw_apb_timer_of: Mark a few more functions as __init
clocksource: Put nodes passed to CLOCKSOURCE_OF_DECLARE callbacks centrally
arm: zynq: Enable arm_global_timer
...
Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use
clockevents_config_and_register() where possible" caused a regression
for some of the converted subarchs.
The reason is, that the clockevents core code converts the minimal
hardware tick delta to a nanosecond value for core internal
usage. This conversion is affected by integer math rounding loss, so
the backwards conversion to hardware ticks will likely result in a
value which is less than the configured hardware limitation. The
affected subarchs used their own workaround (SIGH!) which got lost in
the conversion.
The solution for the issue at hand is simple: adding evt->mult - 1 to
the shifted value before the integer divison in the core conversion
function takes care of it. But this only works for the case where for
the scaled math mult/shift pair "mult <= 1 << shift" is true. For the
case where "mult > 1 << shift" we can apply the rounding add only for
the minimum delta value to make sure that the backward conversion is
not less than the given hardware limit. For the upper bound we need to
omit the rounding add, because the backwards conversion is always
larger than the original latch value. That would violate the upper
bound of the hardware device.
Though looking closer at the details of that function reveals another
bogosity: The upper bounds check is broken as well. Checking for a
resulting "clc" value greater than KTIME_MAX after the conversion is
pointless. The conversion does:
u64 clc = (latch << evt->shift) / evt->mult;
So there is no sanity check for (latch << evt->shift) exceeding the
64bit boundary. The latch argument is "unsigned long", so on a 64bit
arch the handed in argument could easily lead to an unnoticed shift
overflow. With the above rounding fix applied the calculation before
the divison is:
u64 clc = (latch << evt->shift) + evt->mult - 1;
So we need to make sure, that neither the shift nor the rounding add
is overflowing the u64 boundary.
[ukl: move assignment to rnd after eventually changing mult, fix build
issue and correct comment with the right math]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: nicolas.ferre@atmel.com
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: john.stultz@linaro.org
Cc: kernel@pengutronix.de
Cc: Ronald Wahl <ronald.wahl@raritan.com>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
sysfs_get_uname() is erroneously declared as returning size_t even
though it may return a negative value, specifically -EINVAL. Its
callers then check whether its return value is less than zero and indeed
that is never the case for size_t.
This patch changes sysfs_get_uname() to return ssize_t and makes sure
its callers use ssize_t accordingly.
Signed-off-by: Patrick Palka <patrick@parcs.ath.cx>
[jstultz: Didn't apply cleanly, as a similar partial fix was also applied
so had to resolve the collisions]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide
on ARM. (http://bugs.ruby-lang.org/issues/9008)
Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no
RTC device is present) intruduced to return ENOTSUPP when
clock_get{time,res} can't find a RTC device. However this is incorrect.
First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the
closest userland equivlents).
Second, Posix and Linux man pages agree that clock_gettime and
clock_getres should return EINVAL if clk_id argument is invalid.
While the arugment that the clockid is valid, but just not supported
on this hardware could be made, this is just a technicality that
doesn't help userspace applicaitons, and only complicates error
handling.
Thus, this patch changes the code to use EINVAL.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: stable <stable@vger.kernel.org> #3.0 and up
Reported-by: Vit Ondruch <v.ondruch@tiscali.cz>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[jstultz: Tweaks to commit message to include full rational]
Signed-off-by: John Stultz <john.stultz@linaro.org>
We can enable/disable timer statistics collection via:
echo [1|0] > /proc/timers_stats
and it would be nice if apps had the ability to check
what the current collection status is.
This patch adds a 'Collection: active/inactive' line to display the
current timer collection status.
Also bump up the timer stats version to v0.3.
Signed-off-by: Dong Zhu <bluezhudong@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20131010075618.GH2139@zhudong.nay.redhat.com
[ Improved the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull more timekeeping items for v3.13 from John Stultz:
* Small cleanup in the clocksource code.
* Fix for rtc-pl031 to let it work with alarmtimers.
* Move arm64 to using the generic sched_clock framework & resulting
cleanup in the generic sched_clock code.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Nobody is using sched_clock_func() anymore now that sched_clock
supports up to 64 bits. Remove the hook so that new code only
uses sched_clock_register().
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Pull (mostly) ARM clocksource driver updates from Daniel Lezcano:
" - Soren Brinkmann added FEAT_PERCPU to a clock device when it is local
per cpu. This feature prevents the clock framework to choose a per cpu
timer as a broadcast timer. This problem arised when the ARM global
timer is used when switching to the broadcast timer which is the case
now on Xillinx with its cpuidle driver.
- Stephen Boyd extended the generic sched_clock code to support 64bit
counters and removes the setup_sched_clock deprecation, as that causes
lots of warnings since there's still users in the arch/arm tree. He
added also the CLOCK_SOURCE_SUSPEND_NONSTOP flag on the architected
timer as they continue counting during suspend.
- Uwe Kleine-König added some missing __init sections and consolidated the
code by moving the of_node_put call from the drivers to the function
clocksource_of_init. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge updated full dynticks support from Frederic Weisbecker:
- support 32-bit systems (full dynticks was 64-bit only before)
- support ARM
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'v3.12-rc3' into timers/core
Merge Linux 3.12-rc3 - refresh the tree with the latest fixes before merging new bits.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On most ARM systems the per-cpu clockevents are truly per-cpu in
the sense that they can't be controlled on any other CPU besides
the CPU that they interrupt. If one of these clockevents were to
become a broadcast source we will run into a lot of trouble
because the broadcast source is enabled on the first CPU to go
into deep idle (if that CPU suffers from FEAT_C3_STOP) and that
could be a different CPU than what the clockevent is interrupting
(or even worse the CPU that the clockevent interrupts could be
offline).
Theoretically it's possible to support per-cpu clockevents as the
broadcast source but so far we haven't needed this and supporting
it is rather complicated. Let's just deny the possibility for now
until this becomes a reality (let's hope it never does!).
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
The CONFIG_64BIT requirement on vtime can finally be removed
since we now depend on HAVE_VIRT_CPU_ACCOUNTING_GEN which
already takes care of the arch ability to handle nsecs based
cputime_t safely.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. In order
to use that feature, arch code should be audited to ensure there are no
races in concurrent read/write of cputime_t. For example,
reading/writing 64-bit cputime_t on some 32-bit arches may require
multiple accesses for low and high value parts, so proper locking
is needed to protect against concurrent accesses.
Therefore, add CONFIG_HAVE_VIRT_CPU_ACCOUNTING_GEN which arches can
enable after they've been audited for potential races.
This option is automatically enabled on 64-bit platforms.
Feature requested by Frederic Weisbecker.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Pull timer fix from Ingo Molnar:
"An NTP related lockup fix"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Fix HRTICK related deadlock from ntp lock changes
sysfs_override_clocksource(): The expression 'if (ret >= 0)' is always true.
This will cause clocksource_select() to always run.
Thus modified ret to be of type ssize_t.
sysfs_unbind_clocksource(): The expression 'if (ret < 0)' is always false.
So in case sysfs_get_uname() failed, the expression won't take an effect.
Thus modified ret to be of type ssize_t.
Signed-off-by: Elad Wexler <elad.wexler@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Gerlando Falauto reported that when HRTICK is enabled, it is
possible to trigger system deadlocks. These were hard to
reproduce, as HRTICK has been broken in the past, but seemed
to be connected to the timekeeping_seq lock.
Since seqlock/seqcount's aren't supported w/ lockdep, I added
some extra spinlock based locking and triggered the following
lockdep output:
[ 15.849182] ntpd/4062 is trying to acquire lock:
[ 15.849765] (&(&pool->lock)->rlock){..-...}, at: [<ffffffff810aa9b5>] __queue_work+0x145/0x480
[ 15.850051]
[ 15.850051] but task is already holding lock:
[ 15.850051] (timekeeper_lock){-.-.-.}, at: [<ffffffff810df6df>] do_adjtimex+0x7f/0x100
<snip>
[ 15.850051] Chain exists of: &(&pool->lock)->rlock --> &p->pi_lock --> timekeeper_lock
[ 15.850051] Possible unsafe locking scenario:
[ 15.850051]
[ 15.850051] CPU0 CPU1
[ 15.850051] ---- ----
[ 15.850051] lock(timekeeper_lock);
[ 15.850051] lock(&p->pi_lock);
[ 15.850051] lock(timekeeper_lock);
[ 15.850051] lock(&(&pool->lock)->rlock);
[ 15.850051]
[ 15.850051] *** DEADLOCK ***
The deadlock was introduced by 06c017fdd4 ("timekeeping:
Hold timekeepering locks in do_adjtimex and hardpps") in 3.10
This patch avoids this deadlock, by moving the call to
schedule_delayed_work() outside of the timekeeper lock
critical section.
Reported-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Tested-by: Lin Ming <minggr@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable <stable@vger.kernel.org> #3.11, 3.10
Link: http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull timers/nohz changes from Ingo Molnar:
"It mostly contains fixes and full dynticks off-case optimizations, by
Frederic Weisbecker"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
nohz: Include local CPU in full dynticks global kick
nohz: Optimize full dynticks's sched hooks with static keys
nohz: Optimize full dynticks state checks with static keys
nohz: Rename a few state variables
vtime: Always debug check snapshot source _before_ updating it
vtime: Always scale generic vtime accounting results
vtime: Optimize full dynticks accounting off case with static keys
vtime: Describe overriden functions in dedicated arch headers
m68k: hardirq_count() only need preempt_mask.h
hardirq: Split preempt count mask definitions
context_tracking: Split low level state headers
vtime: Fix racy cputime delta update
vtime: Remove a few unneeded generic vtime state checks
context_tracking: User/kernel broundary cross trace events
context_tracking: Optimize context switch off case with static keys
context_tracking: Optimize guest APIs off case with static key
context_tracking: Optimize main APIs off case with static key
context_tracking: Ground setup for static key use
context_tracking: Remove full dynticks' hacky dependency on wide context tracking
nohz: Only enable context tracking on full dynticks CPUs
...
Pull RCU updates from Paul E. McKenney:
"
* Update RCU documentation. These were posted to LKML at
https://lkml.org/lkml/2013/8/19/611.
* Miscellaneous fixes. These were posted to LKML at
https://lkml.org/lkml/2013/8/19/619.
* Full-system idle detection. This is for use by Frederic
Weisbecker's adaptive-ticks mechanism. Its purpose is
to allow the timekeeping CPU to shut off its tick when
all other CPUs are idle. These were posted to LKML at
https://lkml.org/lkml/2013/8/19/648.
* Improve rcutorture test coverage. These were posted to LKML at
https://lkml.org/lkml/2013/8/19/675.
"
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit adds the state machine that takes the per-CPU idle data
as input and produces a full-system-idle indication as output. This
state machine is driven out of RCU's quiescent-state-forcing
mechanism, which invokes rcu_sysidle_check_cpu() to collect per-CPU
idle state and then rcu_sysidle_report() to drive the state machine.
The full-system-idle state is sampled using rcu_sys_is_idle(), which
also drives the state machine if RCU is idle (and does so by forcing
RCU to become non-idle). This function returns true if all but the
timekeeping CPU (tick_do_timer_cpu) are idle and have been idle long
enough to avoid memory contention on the full_sysidle_state state
variable. The rcu_sysidle_force_exit() may be called externally
to reset the state machine back into non-idle state.
For large systems the state machine is driven out of RCU's
force-quiescent-state logic, which provides good scalability at the price
of millisecond-scale latencies on the transition to full-system-idle
state. This is not so good for battery-powered systems, which are usually
small enough that they don't need to care about scalability, but which
do care deeply about energy efficiency. Small systems therefore drive
the state machine directly out of the idle-entry code. The number of
CPUs in a "small" system is defined by a new NO_HZ_FULL_SYSIDLE_SMALL
Kconfig parameter, which defaults to 8. Note that this is a build-time
definition.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
[ paulmck: Use true and false for boolean constants per Lai Jiangshan. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Simplify logic and provide better comments for memory barriers,
based on review comments and questions by Lai Jiangshan. ]
Correct an issue with /proc/timer_list reported by Holger.
When reading from the proc file with a sufficiently small buffer, 2k so
not really that small, there was one could get hung trying to read the
file a chunk at a time.
The timer_list_start function failed to account for the possibility that
the offset was adjusted outside the timer_list_next.
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Reported-by: Holger Hans Peter Freyther <holger@freyther.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Berke Durak <berke.durak@xiphos.com>
Cc: Jeff Layton <jlayton@redhat.com>
Tested-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org> # 3.10.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current code requires that the scheduled update of the RTC happens
in the closest tick to the half of the second. This seems to be
difficult to achieve reliably. The scheduled work may be missing the
target time by a tick or two and be constantly rescheduled every second.
Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute
update interval by several milliseconds, this shouldn't affect the
overall accuracy of the RTC much.
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Pull timer fixes from Ingo Molnar:
"Three small fixlets"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz: fix compile warning in tick_nohz_init()
nohz: Do not warn about unstable tsc unless user uses nohz_full
sched_clock: Fix integer overflow
At least one CPU must keep the scheduling-clock tick running for
timekeeping purposes whenever there is a non-idle CPU. However, with
the new nohz_full adaptive-idle machinery, it is difficult to distinguish
between all CPUs really being idle as opposed to all non-idle CPUs being
in adaptive-ticks mode. This commit therefore adds a Kconfig parameter
as a first step towards enabling a scalable detection of full-system
idle state.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
[ paulmck: Update help text per Frederic Weisbecker. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
tick_nohz_full_kick_all() is useful to notify all full dynticks
CPUs that there is a system state change to checkout before
re-evaluating the need for the tick.
Unfortunately this is implemented using smp_call_function_many()
that ignores the local CPU. This CPU also needs to re-evaluate
the tick.
on_each_cpu_mask() is not useful either because we don't want to
re-evaluate the tick state in place but asynchronously from an IPI
to avoid messing up with any random locking scenario.
So lets call tick_nohz_full_kick() from tick_nohz_full_kick_all()
so that the usual irq work takes care of it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375460996-16329-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull nohz improvements from Frederic Weisbecker:
" It mostly contains fixes and full dynticks off-case optimizations. I believe that
distros want to enable this feature so it seems important to optimize the case
where the "nohz_full=" parameter is empty. ie: I'm trying to remove any performance
regression that comes with NO_HZ_FULL=y when the feature is not used.
This patchset improves the current situation a lot (off-case appears to be around 11% faster
with hackbench, although I guess it may vary depending on the configuration but it should be
significantly faster in any case) now there is still some work to do: I can still observe a
remaining loss of 1.6% throughput seen with hackbench compared to CONFIG_NO_HZ_FULL=n. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Scheduler IPIs and task context switches are serious fast path.
Let's try to hide as much as we can the impact of full
dynticks APIs' off case that are called on these sites
through the use of static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
These APIs are frequenctly accessed and priority is given
to optimize the full dynticks off-case in order to let
distros enable this feature without suffering from
significant performance regressions.
Let's inline these APIs and optimize them with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Rename the full dynticks's cpumask and cpumask state variables
to some more exportable names.
These will be used later from global headers to optimize
the main full dynticks APIs in conjunction with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Now that the full dynticks subsystem only enables the context tracking
on full dynticks CPUs, lets remove the dependency on CONTEXT_TRACKING_FORCE
This dependency was a hack to enable the context tracking widely for the
full dynticks susbsystem until the latter becomes able to enable it in a
more CPU-finegrained fashion.
Now CONTEXT_TRACKING_FORCE only stands for testing on archs that
work on support for the context tracking while full dynticks can't be
used yet due to unmet dependencies. It simulates a system where all CPUs
are full dynticks so that RCU user extended quiescent states and dynticks
cputime accounting can be tested on the given arch.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
The context tracking subsystem has the ability to selectively
enable the tracking on any defined subset of CPU. This means that
we can define a CPU range that doesn't run the context tracking
and another range that does.
Now what we want in practice is to enable the tracking on full
dynticks CPUs only. In order to perform this, we just need to pass
our full dynticks CPU range selection from the full dynticks
subsystem to the context tracking.
This way we can spare the overhead of RCU user extended quiescent
state and vtime maintainance on the CPUs that are outside the
full dynticks range. Just keep in mind the raw context tracking
itself is still necessary everywhere.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
The ARM architected system counter has at least 56 usable bits.
Add support for counters with more than 32 bits to the generic
sched_clock implementation so we can increase the time between
wakeups due to dealing with wrap-around on these devices while
benefiting from the irqtime accounting and suspend/resume
handling that the generic sched_clock code already has. On my
system using 56 bits over 32 bits changes the wraparound time
from a few minutes to an hour. For faster running counters (GHz
range) this is even more important because we may not be able to
execute the timer in time to deal with the wraparound if only 32
bits are used.
We choose a maxsec value of 3600 seconds because we assume no
system will go idle for more than an hour. In the future we may
need to increase this value.
Note: All users should switch over to the 64-bit read function so
we can remove setup_sched_clock() in favor of sched_clock_register().
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In the next patch we're going to increase the number of bits that
the generic sched_clock can handle to be greater than 32. With
more than 32 bits the wraparound time can be larger than what can
fit into the units that msecs_to_jiffies takes (unsigned int).
Luckily, the wraparound is initially calculated in nanoseconds
which we can easily use with hrtimers, so switch to using an
hrtimer.
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
[jstultz: Fixup hrtimer intitialization order issue]
Signed-off-by: John Stultz <john.stultz@linaro.org>
We're going to increase the cyc value to 64 bits in the near
future. Doing that is going to break the custom seqcount
implementation in the sched_clock code because 64 bit numbers
aren't guaranteed to be atomic. Replace the cyc_copy with a
seqcount to avoid this problem.
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
We need to calculate the same number in the clocksource code and
the sched_clock code, so extract this code into its own function.
We also drop the min_t and just use min() because the two types
are the same.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
cpu is not used after commit 5b8621a68f
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
If the user enables CONFIG_NO_HZ_FULL and runs the kernel on a machine
with an unstable TSC, it will produce a WARN_ON dump as well as taint
the kernel. This is a bit extreme for a kernel that just enables a
feature but doesn't use it.
The warning should only happen if the user tries to use the feature by
either adding nohz_full to the kernel command line, or by enabling
CONFIG_NO_HZ_FULL_ALL that makes nohz used on all CPUs at boot up. Note,
this second feature should not (yet) be used by distros or anyone that
doesn't care if NO_HZ is used or not.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The expression '(1 << 32)' happens to evaluate as 0 on ARM, but
it evaluates as 1 on xtensa and x86_64. This zeros sched_clock_mask,
and breaks sched_clock().
Set the type of 1 to 'unsigned long long' to get the value we need.
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: John Stultz <john.stultz@linaro.org>
If I explicitly disable the clocksource watchdog in the x86 Kconfig,
the x86 kernel will not compile unless this is properly defined.
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.
[1] https://lkml.org/lkml/2013/5/20/589
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
On ARM systems the dummy clockevent is registered with the cpu
hotplug notifier chain before any other per-cpu clockevent. This
has the side-effect of causing the dummy clockevent to be
registered first in every hotplug sequence. Because the dummy is
first, we'll try to turn the broadcast source on but the code in
tick_device_uses_broadcast() assumes the broadcast source is in
periodic mode and calls tick_broadcast_start_periodic()
unconditionally.
On boot this isn't a problem because we typically haven't
switched into oneshot mode yet (if at all). During hotplug, if
the broadcast source isn't in periodic mode we'll replace the
broadcast oneshot handler with the broadcast periodic handler and
start emulating oneshot mode when we shouldn't. Due to the way
the broadcast oneshot handler programs the next_event it's
possible for it to contain KTIME_MAX and cause us to hang the
system when the periodic handler tries to program the next tick.
Fix this by using the appropriate function to start the broadcast
source.
Reported-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mark Rutland <Mark.Rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: ARM kernel mailing list <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joseph Lo <josephl@nvidia.com>
Link: http://lkml.kernel.org/r/20130711140059.GA27430@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull nohz updates/fixes from Frederic Weisbecker:
' Note that "watchdog: Boot-disable by default on full dynticks" is a temporary
solution to solve the issue with the watchdog that prevents the tick from
stopping. This is to make sure that 3.11 doesn't have that problem as several
people complained about it.
A proper and longer term solution has been proposed by Peterz:
http://lkml.kernel.org/r/20130618103632.GO3204@twins.programming.kicks-ass.net
'
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Up to commit 5d33b883a (clocksource: Always verify highres capability)
we had no sanity check when selecting a clocksource, which prevented
that a non highres capable clocksource is used when the system already
switched to highres/nohz mode.
The new sanity check works as Alex and Tim found out. It prevents the
TSC from being used. This happens because on x86 the boot process
looks like this:
tsc_start_freqency_validation(TSC);
clocksource_register(HPET);
clocksource_done_booting();
clocksource_select()
Selects HPET which is valid for high-res
switch_to_highres();
clocksource_register(TSC);
TSC is not selected, because it is not yet
flagged as VALID_HIGH_RES
clocksource_watchdog()
Validates TSC for highres, but that does not make TSC
the current clocksource.
Before the sanity check was added, we installed TSC unvalidated which
worked most of the time. If the TSC was really detected as unstable,
then the unstable logic removed it and installed HPET again.
The sanity check is correct and needed. So the watchdog needs to kick
a reselection of the clocksource, when it qualifies TSC as a valid
high res clocksource.
To solve this, we mark the clocksource which got the flag
CLOCK_SOURCE_VALID_FOR_HRES set by the watchdog with an new flag
CLOCK_SOURCE_RESELECT and trigger the watchdog thread. The watchdog
thread evaluates the flag and invokes clocksource_select() when set.
To avoid that the clocksource_done_booting() code, which is about to
install the first real clocksource anyway, needs to go through
clocksource_select and tick_oneshot_notify() pointlessly, split out
the clocksource_watchdog_kthread() list walk code and invoke the
select/notify only when called from clocksource_watchdog_kthread().
So clocksource_done_booting() can utilize the same splitout code
without the select/notify invocation and the clocksource_mutex
unlock/relock dance.
Reported-and-tested-by: Alex Shi <alex.shi@intel.com>
Cc: Hans Peter Anvin <hpa@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Tested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1307042239150.11637@ionos.tec.linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core
Frederic sayed: "Most of these patches have been hanging around for
several month now, in -mmotm for a significant chunk. They already
missed a few releases."
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The recent implementation of a generic dummy timer resulted in a
different registration order of per cpu local timers which made the
broadcast control logic go belly up.
If the dummy timer is the first clock event device which is registered
for a CPU, then it is installed, the broadcast timer is initialized
and the CPU is marked as broadcast target.
If a real clock event device is installed after that, we can fail to
take the CPU out of the broadcast mask. In the worst case we end up
with two periodic timer events firing for the same CPU. One from the
per cpu hardware device and one from the broadcast.
Now the problem is that we have no way to distinguish whether the
system is in a state which makes broadcasting necessary or the
broadcast bit was set due to the nonfunctional dummy timer
installment.
To solve this we need to keep track of the system state seperately and
provide a more detailed decision logic whether we keep the CPU in
broadcast mode or not.
The old decision logic only clears the broadcast mode, if the newly
installed clock event device is not affected by power states.
The new logic clears the broadcast mode if one of the following is
true:
- The new device is not affected by power states.
- The system is not in a power state affected mode
- The system has switched to oneshot mode. The oneshot broadcast is
controlled from the deep idle state. The CPU is not in idle at
this point, so it's safe to remove it from the mask.
If we clear the broadcast bit for the CPU when a new device is
installed, we also shutdown the broadcast device when this was the
last CPU in the broadcast mask.
If the broadcast bit is kept, then we leave the new device in shutdown
state and rely on the broadcast to deliver the timer interrupts via
the broadcast ipis.
Reported-and-tested-by: Stehle Vincent-B46079 <B46079@freescale.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>,
Cc: Mark Rutland <mark.rutland@arm.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1307012153060.4013@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When the system switches from periodic to oneshot mode, the broadcast
logic causes a possibility that a CPU which has not yet switched to
oneshot mode puts its own clock event device into oneshot mode without
updating the state and the timer handler.
CPU0 CPU1
per cpu tickdev is in periodic mode
and switched to broadcast
Switch to oneshot mode
tick_broadcast_switch_to_oneshot()
cpumask_copy(tick_oneshot_broacast_mask,
tick_broadcast_mask);
broadcast device mode = oneshot
Timer interrupt
irq_enter()
tick_check_oneshot_broadcast()
dev->set_mode(ONESHOT);
tick_handle_periodic()
if (dev->mode == ONESHOT)
dev->next_event += period;
FAIL.
We fail, because dev->next_event contains KTIME_MAX, if the device was
in periodic mode before the uncontrolled switch to oneshot happened.
We must copy the broadcast bits over to the oneshot mask, because
otherwise a CPU which relies on the broadcast would not been woken up
anymore after the broadcast device switched to oneshot mode.
So we need to verify in tick_check_oneshot_broadcast() whether the CPU
has already switched to oneshot mode. If not, leave the device
untouched and let the CPU switch controlled into oneshot mode.
This is a long standing bug, which was never noticed, because the main
user of the broadcast x86 cannot run into that scenario, AFAICT. The
nonarchitected timer mess of ARM creates a gazillion of differently
broken abominations which trigger the shortcomings of that broadcast
code, which better had never been necessary in the first place.
Reported-and-tested-by: Stehle Vincent-B46079 <B46079@freescale.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>,
Cc: Mark Rutland <mark.rutland@arm.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1307012153060.4013@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In periodic mode we remove offline cpus from the broadcast propagation
mask. In oneshot mode we fail to do so. This was not a problem so far,
but the recent changes to the broadcast propagation introduced a
constellation which can result in a NULL pointer dereference.
What happens is:
CPU0 CPU1
idle()
arch_idle()
tick_broadcast_oneshot_control(OFF);
set cpu1 in tick_broadcast_force_mask
if (cpu_offline())
arch_cpu_dead()
cpu_dead_cleanup(cpu1)
cpu1 tickdevice pointer = NULL
broadcast interrupt
dereference cpu1 tickdevice pointer -> OOPS
We dereference the pointer because cpu1 is still set in
tick_broadcast_force_mask and tick_do_broadcast() expects a valid
cpumask and therefor lacks any further checks.
Remove the cpu from the tick_broadcast_force_mask before we set the
tick device pointer to NULL. Also add a sanity check to the oneshot
broadcast function, so we can detect such issues w/o crashing the
machine.
Reported-by: Prarit Bhargava <prarit@redhat.com>
Cc: athorlton@sgi.com
Cc: CAI Qian <caiqian@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1306261303260.4013@ionos.tec.linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If the clock was set (stepped), set the action parameter to functions
in the pvclock gtod notifier chain to non-zero. This allows the
callee to only do work if the clock was stepped.
This will be used on Xen as the synchronization of the Xen wallclock
to the control domain's (dom0) system time will be done with this
notifier and updating on every timer tick is unnecessary and too
expensive.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-4-git-send-email-david.vrabel@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Instead of passing multiple bools to timekeeping_updated(), define
flags and use a single 'action' parameter. It is then more obvious
what each timekeeping_update() call does.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-3-git-send-email-david.vrabel@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
On an SMP system with only one global clockevent and a dummy
clockevent per CPU we run into problems. We want the dummy
clockevents to be registered as the per CPU tick devices, but
we can only achieve that if we register the dummy clockevents
before the global clockevent or if we artificially inflate the
rating of the dummy clockevents to be higher than the rating
of the global clockevent. Failure to do so leads to boot
hangs when the dummy timers are registered on all other CPUs
besides the CPU that accepted the global clockevent as its tick
device and there is no broadcast timer to poke the dummy
devices.
If we're registering multiple clockevents and one clockevent is
global and the other is local to a particular CPU we should
choose to use the local clockevent regardless of the rating of
the device. This way, if the clockevent is a dummy it will take
the tick device duty as long as there isn't a higher rated tick
device and any global clockevent will be bumped out into
broadcast mode, fixing the problem described above.
Reported-and-tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: soren.brinkmann@xilinx.com
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20130613183950.GA32061@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The recent modification in the cpuidle framework consolidated the
timer broadcast code across the different drivers by setting a new
flag in the idle state. It tells the cpuidle core code to enter/exit
the broadcast mode for the cpu when entering a deep idle state. The
broadcast timer enter/exit is no longer handled by the back-end
driver.
This change made the local interrupt to be enabled *before* calling
CLOCK_EVENT_NOTIFY_EXIT.
On a tegra114, a four cores system, when the flag has been introduced
in the driver, the following warning appeared:
WARNING: at kernel/time/tick-broadcast.c:578 tick_broadcast_oneshot_control
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 3.10.0-rc3-next-20130529+ #15
[<c00667f8>] (tick_broadcast_oneshot_control+0x1a4/0x1d0) from [<c0065cd0>] (tick_notify+0x240/0x40c)
[<c0065cd0>] (tick_notify+0x240/0x40c) from [<c0044724>] (notifier_call_chain+0x44/0x84)
[<c0044724>] (notifier_call_chain+0x44/0x84) from [<c0044828>] (raw_notifier_call_chain+0x18/0x20)
[<c0044828>] (raw_notifier_call_chain+0x18/0x20) from [<c00650cc>] (clockevents_notify+0x28/0x170)
[<c00650cc>] (clockevents_notify+0x28/0x170) from [<c033f1f0>] (cpuidle_idle_call+0x11c/0x168)
[<c033f1f0>] (cpuidle_idle_call+0x11c/0x168) from [<c000ea94>] (arch_cpu_idle+0x8/0x38)
[<c000ea94>] (arch_cpu_idle+0x8/0x38) from [<c005ea80>] (cpu_startup_entry+0x60/0x134)
[<c005ea80>] (cpu_startup_entry+0x60/0x134) from [<804fe9a4>] (0x804fe9a4)
I don't have the hardware, so I wasn't able to reproduce the warning
but after looking a while at the code, I deduced the following:
1. the CPU2 enters a deep idle state and sets the broadcast timer
2. the timer expires, the tick_handle_oneshot_broadcast function is
called, setting the tick_broadcast_pending_mask and waking up the
idle cpu CPU2
3. the CPU2 exits idle handles the interrupt and then invokes
tick_broadcast_oneshot_control with CLOCK_EVENT_NOTIFY_EXIT which
runs the following code:
[...]
if (dev->next_event.tv64 == KTIME_MAX)
goto out;
if (cpumask_test_and_clear_cpu(cpu,
tick_broadcast_pending_mask))
goto out;
[...]
So if there is no next event scheduled for CPU2, we fulfil the
first condition and jump out without clearing the
tick_broadcast_pending_mask.
4. CPU2 goes to deep idle again and calls
tick_broadcast_oneshot_control with CLOCK_NOTIFY_EVENT_ENTER but
with the tick_broadcast_pending_mask set for CPU2, triggering the
warning.
The issue only surfaced due to the modifications of the cpuidle
framework, which resulted in interrupts being enabled before the call
to the clockevents code. If the call happens before interrupts have
been enabled, the warning cannot trigger, because there is still the
event pending which caused the broadcast timer expiry.
Move the check for the next event below the check for the pending bit,
so the pending bit gets cleared whether an event is scheduled on the
cpu or not.
[ tglx: Massaged changelog ]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reported-and-tested-by: Joseph Lo <josephl@nvidia.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/1371485735-31249-1-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Building full dynticks now implies that all CPUs are forced
into RCU nocb mode through CONFIG_RCU_NOCB_CPU_ALL.
The dynamic check has become useless.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
If the user configures NO_HZ_FULL and defines nohz_full=XXX on the
kernel command line, or enables NO_HZ_FULL_ALL, but nohz fails
due to the machine having a unstable clock, warn about it.
We do not want users thinking that they are getting the benefit
of nohz when their machine can not support it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
There is a small race between when the cycle count is read from
the hardware and when the epoch stabilizes. Consider this
scenario:
CPU0 CPU1
---- ----
cyc = read_sched_clock()
cyc_to_sched_clock()
update_sched_clock()
...
cd.epoch_cyc = cyc;
epoch_cyc = cd.epoch_cyc;
...
epoch_ns + cyc_to_ns((cyc - epoch_cyc)
The cyc on cpu0 was read before the epoch changed. But we
calculate the nanoseconds based on the new epoch by subtracting
the new epoch from the old cycle count. Since epoch is most likely
larger than the old cycle count we calculate a large number that
will be converted to nanoseconds and added to epoch_ns, causing
time to jump forward too much.
Fix this problem by reading the hardware after the epoch has
stabilized.
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Nothing about the sched_clock implementation in the ARM port is
specific to the architecture. Generalize the code so that other
architectures can use it by selecting GENERIC_SCHED_CLOCK.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
[jstultz: Merge minor collisions with other patches in my tree]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Export symbols so they can be used by
drivers/staging/android/alarm-dev.c if it is built as a module.
So far alarm-dev is built-in but module support is planned (see
drivers/staging/android/TODO).
Signed-off-by: Marcus Gelderie <redmnic@gmail.com>
[jstultz: tweaked commit message, also export newly added functions]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since 7300711e ("clockevents: broadcast fixup possible waiters"),
the timekeeping duty is assigned to the CPU that handles the tick
broadcast clock device by the time it is set in one shot mode.
This is an issue in full dynticks mode where the timekeeping duty
must stay handled by the boot CPU for now. Otherwise it prevents
secondary CPUs from offlining and this breaks
suspend/shutdown/reboot/...
As it appears there is no reason for this timekeeping duty to be
moved to the broadcast CPU, besides nothing prevent it from being
later re-assigned to another target, let's simply remove it.
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In tick_nohz_cpu_down_callback() if the cpu is the one handling
timekeeping, we must return something that stops the CPU_DOWN_PREPARE
notifiers and then start notify CPU_DOWN_FAILED on the already called
notifier call backs.
However traditional errno values are not handled by the notifier unless
these are encapsulated using errno_to_notifier().
Hence the current -EINVAL is misinterpreted and converted to junk after
notifier_to_errno(), leaving the notifier subsystem to random behaviour
such as eventually allowing the cpu to go down.
Fix this by using the standard NOTIFY_BAD instead.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Below is a patch from android kernel that maintains a histogram of
suspend times. Please review and provide feedback.
Statistices on the time spent in suspend are kept in
/sys/kernel/debug/sleep_time.
Cc: Android Kernel Team <kernel-team@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Todd Poynor <toddpoynor@google.com>
Cc: San Mehat <san@google.com>
Cc: Benoit Goby <benoit@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
[zoran.markovic@linaro.org: Re-formatted suspend time table to better
fit expected values. Moved accounting of suspend time into timekeeping
core. Removed CONFIG_SUSPEND_TIME flag and made the feature conditional
on CONFIG_DEBUG_FS. Changed the file name to sleep_time to better fit
terminology in timekeeping core. Changed seq_printf to seq_puts. Tweaked
commit message]
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Add functions needed for hooking up alarmtimer to timerfd:
* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
the expires time has already been updated (as with alarm_forward).
* alarm_forward_now: Similar to hrtimer_forward_now, move the expires
time forward to an interval from the current time of the associated clock.
* alarm_start_relative: Start an alarmtimer with an expires time relative to
the current time of the associated clock.
* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
amount of time remaining until alarm expiry.
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since commit 31ade30692, timekeeping_init()
checks for presence of persistent clock by attempting to read a non-zero
time value. This is an issue on platforms where persistent_clock (instead
is implemented as a free-running counter (instead of an RTC) starting
from zero on each boot and running during suspend. Examples are some ARM
platforms (e.g. PandaBoard).
An attempt to read such a clock during timekeeping_init() may return zero
value and falsely declare persistent clock as missing. Additionally, in
the above case suspend times may be accounted twice (once from
timekeeping_resume() and once from rtc_resume()), resulting in a gradual
drift of system time.
This patch does a run-time correction of the issue by doing the same check
during timekeeping_suspend().
A better long-term solution would have to return error when trying to read
non-existing clock and zero when trying to read an uninitialized clock, but
that would require changing all persistent_clock implementations.
This patch addresses the immediate breakage, for now.
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Feng Tang <feng.tang@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
[jstultz: Tweaked commit message and subject]
Signed-off-by: John Stultz <john.stultz@linaro.org>
kernel/time/ntp.c: In function ‘__hardpps’:
kernel/time/ntp.c:877: warning: unused variable ‘flags’
commit a076b2146f ("ntp: Remove ntp_lock,
using the timekeeping locks to protect ntp state") removed its users,
but not the actual variable.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
commit 7eaeb34305 (clocksource: Provide unbind interface in sysfs)
implemented clocksource_select_fallback() which is not defined for
CONFIG_ARCH_USES_GETTIMEOFFSET=y. Add an empty inline function for
that.
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: fengguang.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
commit 26517f3e (tick: Avoid programming the local cpu timer if
broadcast pending) added a warning if the cpu enters broadcast mode
again while the pending bit is still set. Meelis reported that the
warning triggers. There are two corner cases which have been not
considered:
1) cpuidle calls clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER)
twice. That can result in the following scenario
CPU0 CPU1
cpuidle_idle_call()
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER)
set cpu in tick_broadcast_oneshot_mask
broadcast interrupt
event expired for cpu1
set pending bit
acpi_idle_enter_simple()
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER)
WARN_ON(pending bit)
Move the WARN_ON into the section where we enter broadcast mode so
it wont provide false positives on the second call.
2) safe_halt() enables interrupts, so a broadcast interrupt can be
delivered befor the broadcast mode is disabled. That sets the
pending bit for the CPU which receives the broadcast
interrupt. Though the interrupt is delivered right away from the
broadcast handler and leaves the pending bit stale.
Clear the pending bit for the current cpu in the broadcast handler.
Reported-and-tested-by: Meelis Roos <mroos@linux.ee>
Cc: Len Brown <lenb@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305271841130.4220@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Unbreak architectures which do not use clockevents, but require to
build some of the core timekeeping infrastructure
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Provide a sysfs interface to allow unbinding of clockevent
devices. The device is unbound if it is unused or if there is a
replacement device available. Unbinding of broadcast devices is not
supported as we don't want to foster that nonsense. If no replacement
device is available the unbind returns -EBUSY. Unbind is available
from the kernel and through sysfs, which is necessary to drop the
module refcount.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.499216659@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Split out the clockevent device selection logic. Preparatory patch to
allow unbinding active clockevent devices.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.431796247@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Provide a simple sysfs interface for the clockevent devices. Show the
current active clockevent device.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.371634778@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We want to be able to remove clockevent modules as well. Add a
refcount so we don't remove a module with an active clock event
device.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.307435149@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
No need to call another function and have duplicated cases.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.235746557@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that the notifier chain is gone there are no other users and it's
pointless to nest tick_device_lock inside of clockevents_lock because
there is no other use case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.162888472@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
7+ years and still a single user. Kill it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.098520211@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The unregister call can fail, if the clocksource is the current one
and there is no replacement clocksource available. It can also fail,
if the clocksource is the watchdog clocksource and I'm not going to
provide support for this.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.029915527@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With the module refcount held for the current clocksource there is no
way to unload the module.
Provide a sysfs interface which allows to unbind the clocksource. One
could argue that the clocksource override could be (ab)used to do so,
but the clocksource override cannot be used from the kernel itself,
while an unbind function can be used to programmatically check whether
a clocksource can be shutdown or not.
The unbind functionality uses the new skip current feature of
clocksource_select and verifies that a fallback clocksource has been
installed. If the clocksource which should be unbound is the current
clocksource and no fallback can be found, unbind returns -EBUSY.
This does not support the unbinding of a clocksource which is used as
the watchdog clocksource. No point in fostering crappy hardware.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.964218245@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Split out the user string input for clocksource override. Preparatory
patch for unbind.
[ jstultz: Fix an off by one error ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.895851338@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Preparatory patch for clocksource unbind support.
Split out code from clocksource_select and modify it, so it skips the
current clocksource on request and tries to find a fallback
clocksource. Convert all existing users. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.834965397@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add a module refcount, so the current clocksource cannot be removed
unconditionally.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.762417789@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timekeeping_notify() can fail due cs->enable() failure. Though the
caller does not notice and happily keeps the wrong clocksource as the
current one.
Let the caller know about failure, so the current clocksource will be
shown correctly in sysfs.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.696321912@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If a clocksource has a (wrong) high rating, but can't be used as a
timebase for oneshot tick mode, it is unconditionally selected even
when the system is already in oneshot tick mode. This causes full
system failure.
Verify the clocksource selection against the oneshot mode.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.635040849@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull timer fixes from Thomas Gleixner:
- Cure for not using zalloc in the first place, which leads to random
crashes with CPUMASK_OFF_STACK.
- Revert a user space visible change which broke udev
- Add a missing cpu_online early return introduced by the new full
dyntick conversions
- Plug a long standing race in the timer wheel cpu hotplug code.
Sigh...
- Cleanup NOHZ per cpu data on cpu down to prevent stale data on cpu
up.
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons
timer: Don't reinitialize the cpu base lock during CPU_UP_PREPARE
tick: Don't invoke tick_nohz_stop_sched_tick() if the cpu is offline
tick: Cleanup NOHZ per cpu data on cpu down
tick: Use zalloc_cpumask_var for allocating offstack cpumasks
Kay Sievers noted that the ALWAYS_USE_PERSISTENT_CLOCK config,
which enables some minor compile time optimization to avoid
uncessary code in mostly the suspend/resume path could cause
problems for userland.
In particular, the dependency for RTC_HCTOSYS on
!ALWAYS_USE_PERSISTENT_CLOCK, which avoids setting the time
twice and simplifies suspend/resume, has the side effect
of causing the /sys/class/rtc/rtcN/hctosys flag to always be
zero, and this flag is commonly used by udev to setup the
/dev/rtc symlink to /dev/rtcN, which can cause pain for
older applications.
While the udev rules could use some work to be less fragile,
breaking userland should strongly be avoided. Additionally
the compile time optimizations are fairly minor, and the code
being optimized is likely to be reworked in the future, so
lets revert this change.
Reported-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: stable <stable@vger.kernel.org> #3.9
Cc: Feng Tang <feng.tang@intel.com>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Link: http://lkml.kernel.org/r/1366828376-18124-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
commit 5b39939a4 (nohz: Move ts->idle_calls incrementation into strict
idle logic) moved code out of tick_nohz_stop_sched_tick() and missed
to bail out when the cpu is offline. That's causing subsequent
failures as an offline CPU is supposed to die and not to fiddle with
nohz magic.
Return false in can_stop_idle_tick() if the cpu is offline.
Reported-and-tested-by: Jiri Kosina <jkosina@suse.cz>
Reported-and-tested-by: Prarit Bhargava <prarit@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305132138160.2863@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Prarit reported a crash on CPU offline/online. The reason is that on
CPU down the NOHZ related per cpu data of the dead cpu is not cleaned
up. If at cpu online an interrupt happens before the per cpu tick
device is registered the irq_enter() check potentially sees stale data
and dereferences a NULL pointer.
Cleanup the data after the cpu is dead.
Reported-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Cc: Mike Galbraith <bitbucket@online.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull 'full dynticks' support from Ingo Molnar:
"This tree from Frederic Weisbecker adds a new, (exciting! :-) core
kernel feature to the timer and scheduler subsystems: 'full dynticks',
or CONFIG_NO_HZ_FULL=y.
This feature extends the nohz variable-size timer tick feature from
idle to busy CPUs (running at most one task) as well, potentially
reducing the number of timer interrupts significantly.
This feature got motivated by real-time folks and the -rt tree, but
the general utility and motivation of full-dynticks runs wider than
that:
- HPC workloads get faster: CPUs running a single task should be able
to utilize a maximum amount of CPU power. A periodic timer tick at
HZ=1000 can cause a constant overhead of up to 1.0%. This feature
removes that overhead - and speeds up the system by 0.5%-1.0% on
typical distro configs even on modern systems.
- Real-time workload latency reduction: CPUs running critical tasks
should experience as little jitter as possible. The last remaining
source of kernel-related jitter was the periodic timer tick.
- A single task executing on a CPU is a pretty common situation,
especially with an increasing number of cores/CPUs, so this feature
helps desktop and mobile workloads as well.
The cost of the feature is mainly related to increased timer
reprogramming overhead when a CPU switches its tick period, and thus
slightly longer to-idle and from-idle latency.
Configuration-wise a third mode of operation is added to the existing
two NOHZ kconfig modes:
- CONFIG_HZ_PERIODIC: [formerly !CONFIG_NO_HZ], now explicitly named
as a config option. This is the traditional Linux periodic tick
design: there's a HZ tick going on all the time, regardless of
whether a CPU is idle or not.
- CONFIG_NO_HZ_IDLE: [formerly CONFIG_NO_HZ=y], this turns off the
periodic tick when a CPU enters idle mode.
- CONFIG_NO_HZ_FULL: this new mode, in addition to turning off the
tick when a CPU is idle, also slows the tick down to 1 Hz (one
timer interrupt per second) when only a single task is running on a
CPU.
The .config behavior is compatible: existing !CONFIG_NO_HZ and
CONFIG_NO_HZ=y settings get translated to the new values, without the
user having to configure anything. CONFIG_NO_HZ_FULL is turned off by
default.
This feature is based on a lot of infrastructure work that has been
steadily going upstream in the last 2-3 cycles: related RCU support
and non-periodic cputime support in particular is upstream already.
This tree adds the final pieces and activates the feature. The pull
request is marked RFC because:
- it's marked 64-bit only at the moment - the 32-bit support patch is
small but did not get ready in time.
- it has a number of fresh commits that came in after the merge
window. The overwhelming majority of commits are from before the
merge window, but still some aspects of the tree are fresh and so I
marked it RFC.
- it's a pretty wide-reaching feature with lots of effects - and
while the components have been in testing for some time, the full
combination is still not very widely used. That it's default-off
should reduce its regression abilities and obviously there are no
known regressions with CONFIG_NO_HZ_FULL=y enabled either.
- the feature is not completely idempotent: there is no 100%
equivalent replacement for a periodic scheduler/timer tick. In
particular there's ongoing work to map out and reduce its effects
on scheduler load-balancing and statistics. This should not impact
correctness though, there are no known regressions related to this
feature at this point.
- it's a pretty ambitious feature that with time will likely be
enabled by most Linux distros, and we'd like you to make input on
its design/implementation, if you dislike some aspect we missed.
Without flaming us to crisp! :-)
Future plans:
- there's ongoing work to reduce 1Hz to 0Hz, to essentially shut off
the periodic tick altogether when there's a single busy task on a
CPU. We'd first like 1 Hz to be exposed more widely before we go
for the 0 Hz target though.
- once we reach 0 Hz we can remove the periodic tick assumption from
nr_running>=2 as well, by essentially interrupting busy tasks only
as frequently as the sched_latency constraints require us to do -
once every 4-40 msecs, depending on nr_running.
I am personally leaning towards biting the bullet and doing this in
v3.10, like the -rt tree this effort has been going on for too long -
but the final word is up to you as usual.
More technical details can be found in Documentation/timers/NO_HZ.txt"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
sched: Keep at least 1 tick per second for active dynticks tasks
rcu: Fix full dynticks' dependency on wide RCU nocb mode
nohz: Protect smp_processor_id() in tick_nohz_task_switch()
nohz_full: Add documentation.
cputime_nsecs: use math64.h for nsec resolution conversion helpers
nohz: Select VIRT_CPU_ACCOUNTING_GEN from full dynticks config
nohz: Reduce overhead under high-freq idling patterns
nohz: Remove full dynticks' superfluous dependency on RCU tree
nohz: Fix unavailable tick_stop tracepoint in dynticks idle
nohz: Add basic tracing
nohz: Select wide RCU nocb for full dynticks
nohz: Disable the tick when irq resume in full dynticks CPU
nohz: Re-evaluate the tick for the new task after a context switch
nohz: Prepare to stop the tick on irq exit
nohz: Implement full dynticks kick
nohz: Re-evaluate the tick from the scheduler IPI
sched: New helper to prevent from stopping the tick in full dynticks
sched: Kick full dynticks CPU that have more than one task enqueued.
perf: New helper to prevent full dynticks CPUs from stopping tick
perf: Kick full dynticks CPU if events rotation is needed
...
commit b352bc1cbc (tick: Convert broadcast cpu bitmaps to
cpumask_var_t) broke CONFIG_CPUMASK_OFFSTACK in a very subtle way.
Instead of allocating the cpumasks with zalloc_cpumask_var it uses
alloc_cpumask_var, so we can get random data there, which of course
confuses the logic completely and causes random failures.
Reported-and-tested-by: Dave Jones <davej@redhat.com>
Reported-and-tested-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305032015060.2990@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The scheduler doesn't yet fully support environments
with a single task running without a periodic tick.
In order to ensure we still maintain the duties of scheduler_tick(),
keep at least 1 tick per second.
This makes sure that we keep the progression of various scheduler
accounting and background maintainance even with a very low granularity.
Examples include cpu load, sched average, CFS entity vruntime,
avenrun and events such as load balancing, amongst other details
handled in sched_class::task_tick().
This limitation will be removed in the future once we get
these individual items to work in full dynticks CPUs.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Commit 0637e02939
("nohz: Select wide RCU nocb for full dynticks") intended
to force CONFIG_RCU_NOCB_CPU_ALL=y when full dynticks is
enabled.
However this option is part of a choice menu and Kconfig's
"select" instruction has no effect on such targets.
Fix this by using reverse dependencies on the targets we
don't want instead.
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.
Merge a common upstream merge point that has these
updates.
Conflicts:
include/linux/perf_event.h
kernel/rcutree.h
kernel/rcutree_plugin.h
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Pull more full-dynticks updates from Frederic Weisbecker:
* Get rid of the passive dependency on VIRT_CPU_ACCOUNTING_GEN (finally!)
* Preparation patch to remove the dependency on CONFIG_64BITS
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Turn the full dynticks passive dependency on VIRT_CPU_ACCOUNTING_GEN
to an active one.
The full dynticks Kconfig is currently hidden behind the full dynticks
cputime accounting, which is an awkward and counter-intuitive layout:
the user first has to select the dynticks cputime accounting in order
to make the full dynticks feature to be visible.
We definetly want it the other way around. The usual way to perform
this kind of active dependency is use "select" on the depended target.
Now we can't use the Kconfig "select" instruction when the target is
a "choice".
So this patch inspires on how the RCU subsystem Kconfig interact
with its dependencies on SMP and PREEMPT: we make sure that cputime
accounting can't propose another option than VIRT_CPU_ACCOUNTING_GEN
when NO_HZ_FULL is selected by using the right "depends on" instruction
for each cputime accounting choices.
v2: Keep full dynticks cputime accounting available even without
full dynticks, as per Paul McKenney's suggestion.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
One testbox of mine (Intel Nehalem, 16-way) uses MWAIT for its idle routine,
which apparently can break out of its idle loop rather frequently, with
high frequency.
In that case NO_HZ_FULL=y kernels show high ksoftirqd overhead and constant
context switching, because tick_nohz_stop_sched_tick() will, if
delta_jiffies == 0, mis-identify this as a timer event - activating the
TIMER_SOFTIRQ, which wakes up ksoftirqd.
Fix this by treating delta_jiffies == 0 the same way we treat other short
wakeups, delta_jiffies == 1.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Vitaliy reported that a per cpu HPET timer interrupt crashes the
system during hibernation. What happens is that the per cpu HPET timer
gets shut down when the nonboot cpus are stopped. When the nonboot
cpus are onlined again the HPET code sets up the MSI interrupt which
fires before the clock event device is registered. The event handler
is still set to hrtimer_interrupt, which then crashes the machine due
to highres mode not being active.
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=700333
There is no real good way to avoid that in the HPET code. The HPET
code alrady has a mechanism to detect spurious interrupts when event
handler == NULL for a similar reason.
We can handle that in the clockevent/tick layer and replace the
previous functional handler with a dummy handler like we do in
tick_setup_new_device().
The original clockevents code did this in clockevents_exchange_device(),
but that got removed by commit 7c1e76897 (clockevents: prevent
clockevent event_handler ending up handler_noop) which forgot to fix
it up in tick_shutdown(). Same issue with the broadcast device.
Reported-by: Vitaliy Fillipov <vitalif@yourcmc.ru>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Cc: 700333@bugs.debian.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Remove the dependency on (TREE_RCU || TREE_PREEMPT_RCU). The full
dynticks option already depends on SMP which implies
(whatever flavour of) RCU tree config anyway.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
It's not obvious to find out why the full dynticks subsystem
doesn't always stop the tick: whether this is due to kthreads,
posix timers, perf events, etc...
These new tracepoints are here to help the user diagnose
the failures and test this feature.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
It makes testing and implementation much easier as we
know in advance that all CPUs are RCU nocbs.
Also this prepares to remove the dynamic check for
nohz_full= boot mask to be a subset of rcu_nocbs=
Eventually this should also help removing the requirement
for the boot CPU to be outside the full dynticks range.
Suggested-by: Christoph Lameter <cl@linux.com>
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
When a task is scheduled in, it may have some properties
of its own that could make the CPU reconsider the need for
the tick: posix cpu timers, perf events, ...
So notify the full dynticks subsystem when a task gets
scheduled in and re-check the tick dependency at this
stage. This is done through a self IPI to avoid messing
up with any current lock scenario.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Interrupt exit is a natural place to stop the tick: it happens
after all events happening before and during the irq which
are liable to update the dependency on the tick occured. Also
it makes sure that any check on tick dependency is well ordered
against dynticks kick IPIs.
Bring in the infrastructure that performs the tick dependency
checks on irq exit and shut it down if these checks show that we
can do it safely.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Implement the full dynticks kick that is performed from
IPIs sent by various subsystems (scheduler, posix timers, ...)
when they want to notify about a new event that may
reconsider the dependency on the tick.
Most of the time, such an event end up restarting the tick.
(Part of the design with subsystems providing *_can_stop_tick()
helpers suggested by Peter Zijlstra a while ago).
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
commit 7ec98e15aa (timekeeping: Delay update of clock->cycle_last)
forgot to update tk->cycle_last in the resume path. This results in a
stale value versus clock->cycle_last and prevents resume in the worst
case.
Reported-by: Jiri Slaby <jslaby@suse.cz>
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Linux-pm mailing list <linux-pm@lists.linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1304211648150.21884@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The scheduler IPI is used by the scheduler to kick
full dynticks CPUs asynchronously when more than one
task are running or when a new timer list timer is
enqueued. This way the destination CPU can decide
to restart the tick to handle this new situation.
Now let's call that kick in the scheduler IPI.
(Reusing the scheduler IPI rather than implementing
a new IPI was suggested by Peter Zijlstra a while ago)
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Provide a new kernel config that defaults all CPUs to be part
of the full dynticks range, except the boot one for timekeeping.
This default setting is overriden by the nohz_full= boot option
if passed by the user.
This is helpful for those who don't need a finegrained range
of full dynticks CPU and also for automated testing.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
We need full dynticks CPU to also be RCU nocb so
that we don't have to keep the tick to handle RCU
callbacks.
Make sure the range passed to nohz_full= boot
parameter is a subset of rcu_nocbs=
The CPUs that fail to meet this requirement will be
excluded from the nohz_full range. This is checked
early in boot time, before any CPU has the opportunity
to stop its tick.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
The timekeeping job must be able to run early on boot
because there may be some pre-SMP (and thus pre-initcalls )
components that rely on it. The IO-APIC is one such users
as it tests the timer health by watching jiffies progression.
Given that it happens before we know the initial online
set, we can't rely on it to select a timekeeper. We need
one before SMP time otherwise we simply crash on boot.
To fix this and keep things simple for now, force the boot CPU
outside of the full dynticks range in any case and do this early
on kernel parameter parsing time.
We might want a trickier solution later, expecially for aSMP
architectures that need to assign housekeeping tasks to arbitrary
low power CPUs.
But it's still first pass KISS time for now.
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Provide two new helpers in order to notify the full dynticks CPUs about
some internal system changes against which they may reconsider the state
of their tick. Some practical examples include: posix cpu timers, perf tick
and sched clock tick.
For now the notifying handler, implemented through IPIs, is a stub
that will be implemented when we get the tick stop/restart infrastructure
in.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
tick_oneshot_notify() is used to notify a particular CPU to try
to switch into oneshot mode after a oneshot capable tick device
is registered and tick_clock_notify() is used to notify all CPUs
to try to switch into oneshot mode after a high res clocksource
is registered. There is one caveat; if the tick devices suffer
from FEAT_C3_STOP we don't try to switch into oneshot mode unless
we have a oneshot capable broadcast device already registered.
If the broadcast device is registered after the tick devices that
have FEAT_C3_STOP we'll never try to switch into oneshot mode
again, causing us to be stuck in periodic mode forever. Avoid
this scenario by calling tick_clock_notify() after we register
the broadcast device so that we try to switch into oneshot mode
on all CPUs one more time.
[ tglx: Adopted to timers/core and added a comment ]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/1366219566-29783-1-git-send-email-sboyd@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When running with 4096 cores attemping to read /proc/timer_list will fail
with an ENOMEM condition. On a sufficantly large systems the total amount
of data is more then 4mb, so it won't fit into a single buffer. The
failure can also occur on smaller systems when memory fragmentation is
high as reported by Dave Jones.
Convert /proc/timer_list to a proper seq_file with its own iterator. This
is a little more complex given that we have to make two passes with two
separate headers.
sysrq_timer_list_show also needed to be updated to reflect the fact that
now timer_list_show only does one cpu at at time.
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Reported-by: Dave Jones <davej@redhat.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/1364345790-14577-3-git-send-email-nzimmer@sgi.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Split timer_list_show_tickdevices() into the header printout and pull
the rest up to timer_list_show. This is a preparatory patch for
converting timer_list to a proper seqfile with its own iterator
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Reported-by: Dave Jones <davej@redhat.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/1364345790-14577-2-git-send-email-nzimmer@sgi.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Remove the "single task" statement from CONFIG_NO_HZ_FULL
title. The constraint can be invalidated when tasks from
other sched classes than SCHED_FAIR are running. Moreover
it's possible that hrtick join the party in the future.
Also add a line about the dependency on SMP.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Rename CONFIG_PERIODIC_HZ to CONFIG_HZ_PERIODIC in
order to stay consistent with other tick implementation
entries:
CONFIG_HZ_PERIODIC
CONFIG_NO_HZ_IDLE
CONFIG_NO_HZ_FULL
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
"Extended nohz" was used as a naming base for the full dynticks
API and Kconfig symbols. It reflects the fact the system tries
to stop the tick in more places than just idle.
But that "extended" name is a bit opaque and vague. Rename it to
"full" makes it clearer what the system tries to do under this
config: try to shutdown the tick anytime it can. The various
constraints that prevent that to happen shouldn't be considered
as fundamental properties of this feature but rather technical
issues that may be solved in the future.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
In order to enforce backward compatibility with older
config files, we want the new dynticks-idle Kconfig entry
to default its value to the one of the old CONFIG_NO_HZ symbol
if present.
Namely we want:
config NO_HZ # old obsolete dynticks idle symbol
bool
config NO_HZ_IDLE # new dynticks idle symbol
default NO_HZ
However Kconfig prevents this to work if the old symbol
is not visible. And this is currently the case because
NO_HZ lacks a title in order to show it in make oldconfig
and alike.
To fix this, bring a minimal title and help text to the
obsolete Kconfig entry that explains its purpose. This
makes the "defaulting" to work.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Shorten the seqcount write hold region to the actual update of the
timekeeper and the related data (e.g vsyscall).
On a contemporary x86 system this reduces the maximum latencies on
Preempt-RT from 8us to 4us on the non-timekeeping cores.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Use the shadow timekeeper to do the update_wall_time() adjustments and
then copy it over to the real timekeeper.
Keep the shadow timekeeper in sync when updating stuff outside of
update_wall_time().
This allows us to limit the timekeeper_seq hold time to the update of
the real timekeeper and the vsyscall data in the next patch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
For calculating the new timekeeper values store the new cycle_last
value in the timekeeper and update the clock->cycle_last just when we
actually update the new values.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
For implementing a shadow timekeeper and a split calculation/update
region we need to store the cycle_last value in the timekeeper and
update the value in the clocksource struct only in the update region.
Add the extra storage to the timekeeper.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In order to properly handle the NTP state in future changes to the
timekeeping lock management, this patch moves the management of
all of the ntp state under the timekeeping locks.
This allows us to remove the ntp_lock.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since we are taking the timekeeping locks, just go ahead
and update any tai change directly, rather then dropping
the lock and calling a function that will just take it again.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In moving the NTP state to be protected by the timekeeping locks,
be sure to acquire the timekeeping locks prior to calling
ntp functions.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Since ADJ_SETOFFSET adjusts the timekeeping state, process
it as part of the top level do_adjtimex() function in
timekeeping.c.
This avoids deadlocks that could occur once we change the
ntp locking rules.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In order to change the locking rules, we need to provide
the timespec and tai values rather then having the ntp
logic acquire these values itself.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Move logic that does not need the ntp state to be done
in the timekeeping do_adjtimex() call.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
In preparation for changing the ntp locking rules, move
do_adjtimex and hardpps accessor functions to timekeeping.c,
but keep the code logic in ntp.c.
This patch also introduces a ntp_internal.h file so timekeeping
specific interfaces of ntp.c can be more limitedly shared with
timekeeping.c.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Split out the timex validation done in do_adjtimex into a separate
function. This will help simplify logic in following patches.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Given that we apply a few restrictions on the full dynticks
CPUs range (keep an online timekeeper oustide the range,
then in the future have the range be an RCU nocb CPUs subset),
let's print the final resulting range of full dynticks CPUs to
the user so that he knows what's really going to run.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Now the user has the choice between three implementations of
the timer tick:
* Static periodic tick
* Idle dynticks
* Full dynticks
At least for now, these are mutually exclusive choices, so
let's rely on the proper Kconfig feature to display these
to the user.
A new entry CONFIG_NO_HZ_IDLE is created and the old
CONFIG_NO_HZ maps to it for config file backward compatibility.
The old name was too general now that we have more
granular dynticks implementations.
While at it, add some explanation to help the user on
his decision between the 3 entries.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
We are planning to convert the dynticks Kconfig options layout
into a choice menu. The user must be able to easily pick
any of the following implementations: constant periodic tick,
idle dynticks, full dynticks.
As this implies a mutual exclusion, the two dynticks implementions
need to converge on the selection of a common Kconfig option in order
to ease the sharing of a common infrastructure.
It would thus seem pretty natural to reuse CONFIG_NO_HZ to
that end. It already implements all the idle dynticks code
and the full dynticks depends on all that code for now.
So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and
CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ.
On the other hand we want to stay backward compatible: if
CONFIG_NO_HZ is set in an older config file, we want to
enable CONFIG_NO_HZ_IDLE by default.
But we can't afford both at the same time or we run into
a circular dependency:
1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select
CONFIG_NO_HZ
2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE
We might be able to support that from Kconfig/Kbuild but it
may not be wise to introduce such a confusing behaviour.
So to solve this, create a new CONFIG_NO_HZ_COMMON option
which gathers the common code between idle and full dynticks
(that common code for now is simply the idle dynticks code)
and select it from their referring Kconfig.
Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ
to it for backward compatibility.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
The full dynticks feature only shows up when all its
Kconfig dependencies are met (RCU nocbs, RCU user mode, ...)
This is far from being user friendly as those who want to
activate this feature need to look into the Kconfig files
and iterate through each dependency then activate these
by hand in order to show and select the full dynticks
Kconfig option.
So process the other way around: show up the Kconfig option
if the minimal low level dependencies are met and activate
the high level ones when we enable the feature.
Note there is one exception in the picture:
CONFIG_VIRT_CPU_ACCOUNTING_GEN is part of a Kconfig choice
menu and it appears we can't select it from another Kconfig
selection when it's under such layout. So for now this
particular item stays as a passive dependency.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Yet again, the kbuild test robot saves the day, noting
I left out defining __timekeeping_set_tai_offset as
static. It even sent me this patch.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The "NOHZ: local_softirq_pending" message is a largely informational
message. This makes extra work for customers that have a policy of
investigating all kernel log messages logged at <= KERN_ERR log level.
This patch sets the message to a different log level.
[ tglx: Use pr_warn() ]
Signed-off-by: Rado Vrbovsky <rvrbovsk@redhat.com>
Cc: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/2037057938.893524.1360345050772.JavaMail.root@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We want to shorten the seqcount write hold time. So split the seqlock
into a lock and a seqcount.
Open code the seqwrite_lock in the places which matter and drop the
sequence counter update where it's pointless.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[jstultz: Merge fixups from CLOCK_TAI collisions]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Make the lock a separate entity. Preparatory patch for shadow
timekeeper structure.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[Merged with CLOCK_TAI changes]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Nothing outside of the timekeeping core needs that lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Calculate the cycle interval shifted value once. No functional change,
just makes the code more readable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This add a CLOCK_TAI clockid and the needed accessors.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Currently NTP manages the TAI offset. Since there's plans for a
CLOCK_TAI clockid, push the TAI management into the timekeeping
core.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This way the full nohz CPUs can safely run with the tick
stopped with a guarantee that somebody else is taking
care of the jiffies and GTOD progression.
Once the duty is attributed to a CPU, it won't change. Also that
CPU can't enter into dyntick idle mode or be hot unplugged.
This may later be improved from a power consumption POV. At
least we should be able to share the duty amongst all CPUs
outside the full dynticks range. Then the duty could even be
shared with full dynticks CPUs when those can't stop their
tick for any reason.
But let's start with that very simple approach first.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fix have_nohz_full_mask offcase]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
For extreme usecases such as Real Time or HPC, having
the ability to shutdown the tick when a single task runs
on a CPU is a desired feature:
* Reducing the amount of interrupts improves throughput
for CPU-bound tasks. The CPU is less distracted from its
real job, from an execution time and from the cache point
of views.
* This also improve latency response as we have less critical
sections.
Start with introducing a very simple interface to define
full dynticks CPU: use a boot time option defined cpumask
through the "nohz_extended=" kernel parameter. CPUs that
are part of this range will have their tick shutdown
whenever possible: provided they run a single task and
they don't do kernel activity that require the periodic
tick. These details will be later documented in
Documentation/*
An online CPU must be kept outside this range to handle the
timekeeping.
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
There are some new processors whose TSC clocksource won't stop during
suspend. Currently, after system resumes, kernel will use persistent
clock or RTC to compensate the sleep time, but with these nonstop
clocksources, we could skip the special compensation from external
sources, and just use current clocksource for time recounting.
This can solve some time drift bugs caused by some not-so-accurate or
error-prone RTC devices.
The current way to count suspended time is first try to use the persistent
clock, and then try the RTC if persistent clock can't be used. This
patch will change the trying order to:
suspend-nonstop clocksource -> persistent clock -> RTC
When counting the sleep time with nonstop clocksource, use an accurate way
suggested by Jason Gunthorpe to cover very large delta cycles.
Signed-off-by: Feng Tang <feng.tang@intel.com>
[jstultz: Small optimization, avoiding re-reading the clocksource]
Signed-off-by: John Stultz <john.stultz@linaro.org>
On the CPU which gets woken along with the target CPU of the broadcast
the following happens:
deep_idle()
<-- spurious wakeup
broadcast_exit()
set forced bit
enable interrupts
<-- Nothing happens
disable interrupts
broadcast_enter()
<-- Here we observe the forced bit is set
deep_idle()
Now after that the target CPU of the broadcast runs the broadcast
handler and finds the other CPU in both the broadcast and the forced
mask, sends the IPI and stuff gets back to normal.
So it's not actually harmful, just more evidence for the theory, that
hardware designers have access to very special drug supplies.
Now there is no point in going back to deep idle just to wake up again
right away via an IPI. Provide a check which allows the idle code to
avoid the deep idle transition.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Jason Liu <liu.h.jason@gmail.com>
Link: http://lkml.kernel.org/r/20130306111537.565418308@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Some brilliant hardware implementations wake multiple cores when the
broadcast timer fires. This leads to the following interesting
problem:
CPU0 CPU1
wakeup from idle wakeup from idle
leave broadcast mode leave broadcast mode
restart per cpu timer restart per cpu timer
go back to idle
handle broadcast
(empty mask)
enter broadcast mode
programm broadcast device
enter broadcast mode
programm broadcast device
So what happens is that due to the forced reprogramming of the cpu
local timer, we need to set a event in the future. Now if we manage to
go back to idle before the timer fires, we switch off the timer and
arm the broadcast device with an already expired time (covered by
forced mode). So in the worst case we repeat the above ping pong
forever.
Unfortunately we have no information about what caused the wakeup, but
we can check current time against the expiry time of the local cpu. If
the local event is already in the past, we know that the broadcast
timer is about to fire and send an IPI. So we mark ourself as an IPI
target even if we left broadcast mode and avoid the reprogramming of
the local cpu timer.
This still leaves the possibility that a CPU which is not handling the
broadcast interrupt is going to reach idle again before the IPI
arrives. This can't be solved in the core code and will be handled in
follow up patches.
Reported-by: Jason Liu <liu.h.jason@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Link: http://lkml.kernel.org/r/20130306111537.492045206@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If the local cpu timer stops in deep idle, we arm the broadcast device
and get woken by an IPI. Now when we return from deep idle we reenable
the local cpu timer unconditionally before handling the IPI. But
that's a pointless exercise: the timer is already expired and the IPI
is on the way. And it's an expensive exercise as we use the forced
reprogramming mode so that we do not lose a timer event. This forced
reprogramming will loop at least once in the retry.
To avoid this reprogramming, we mark the cpu in a pending bit mask
before we send the IPI. Now when the IPI target cpu wakes up, it will
see the pending bit set and skip the reprogramming. The reprogramming
of the cpu local timer will happen in the IPI handler which runs the
cpu local timer interrupt function.
Reported-by: Jason Liu <liu.h.jason@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Link: http://lkml.kernel.org/r/20130306111537.431082074@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently tick_check_broadcast_device doesn't reject clock_event_devices
with CLOCK_EVT_FEAT_DUMMY, and may select them in preference to real
hardware if they have a higher rating value. In this situation, the
dummy timer is responsible for broadcasting to itself, and the core
clockevents code may attempt to call non-existent callbacks for
programming the dummy, eventually leading to a panic.
This patch makes tick_check_broadcast_device always reject dummy timers,
preventing this problem.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jon Medhurst (Tixy) <tixy@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull thermal management updates from Zhang Rui:
"Highlights:
- introduction of Dove thermal sensor driver.
- introduction of Kirkwood thermal sensor driver.
- introduction of intel_powerclamp thermal cooling device driver.
- add interrupt and DT support for rcar thermal driver.
- add thermal emulation support which allows platform thermal driver
to do software/hardware emulation for thermal issues."
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux: (36 commits)
thermal: rcar: remove __devinitconst
thermal: return an error on failure to register thermal class
Thermal: rename thermal governor Kconfig option to avoid generic naming
thermal: exynos: Use the new thermal trend type for quick cooling action.
Thermal: exynos: Add support for temperature falling interrupt.
Thermal: Dove: Add Themal sensor support for Dove.
thermal: Add support for the thermal sensor on Kirkwood SoCs
thermal: rcar: add Device Tree support
thermal: rcar: remove machine_power_off() from rcar_thermal_notify()
thermal: rcar: add interrupt support
thermal: rcar: add read/write functions for common/priv data
thermal: rcar: multi channel support
thermal: rcar: use mutex lock instead of spin lock
thermal: rcar: enable CPCTL to use hardware TSC deciding
thermal: rcar: use parenthesis on macro
Thermal: fix a build warning when CONFIG_THERMAL_EMULATION cleared
Thermal: fix a wrong comment
thermal: sysfs: Add a new sysfs node emul_temp for thermal emulation
PM: intel_powerclamp: off by one in start_power_clamp()
thermal: exynos: Miscellaneous fixes to support falling threshold interrupt
...
Pull core locking changes from Ingo Molnar:
"The biggest change is the rwsem lock-steal improvements, both to the
assembly optimized and the spinlock based variants.
The other notable change is the clean up of the seqlock implementation
to be based on the seqcount infrastructure.
The rest is assorted smaller debuggability, cleanup and continued -rt
locking changes."
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rwsem-spinlock: Implement writer lock-stealing for better scalability
futex: Revert "futex: Mark get_robust_list as deprecated"
generic: Use raw local irq variant for generic cmpxchg
lockdep: Selftest: convert spinlock to raw spinlock
seqlock: Use seqcount infrastructure
seqlock: Remove unused functions
ntp: Make ntp_lock raw
intel_idle: Convert i7300_idle_lock to raw_spinlock
locking: Various static lock initializer fixes
lockdep: Print more info when MAX_LOCK_DEPTH is exceeded
rwsem: Implement writer lock-stealing for better scalability
lockdep: Silence warning if CONFIG_LOCKDEP isn't set
watchdog: Use local_clock for get_timestamp()
lockdep: Rename print_unlock_inbalance_bug() to print_unlock_imbalance_bug()
locking/stat: Fix a typo
A large number of cleanups, all over the platforms. This is dominated
largely by the Samsung platforms (s3c, s5p, exynos) and a few of the
others moving code out of arch/arm into more appropriate subsystems.
The clocksource and irqchip drivers are now abstracted to the point
where platforms that are already cleaned up do not need to even specify
the driver they use, it can all get configured from the device tree
as we do for normal device drivers. The clocksource changes basically
touch every single platform in the process.
We further clean up the use of platform specific header files here,
with the goal of turning more of the platforms over to being
"multiplatform" enabled, which implies that they cannot expose
their headers to architecture independent code any more.
It is expected that no functional changes are part of the cleanup.
The overall reduction in total code lines is mostly the result of
removing broken and obsolete code.
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Merge tag 'cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC cleanups from Arnd Bergmann:
"A large number of cleanups, all over the platforms. This is dominated
largely by the Samsung platforms (s3c, s5p, exynos) and a few of the
others moving code out of arch/arm into more appropriate subsystems.
The clocksource and irqchip drivers are now abstracted to the point
where platforms that are already cleaned up do not need to even
specify the driver they use, it can all get configured from the device
tree as we do for normal device drivers. The clocksource changes
basically touch every single platform in the process.
We further clean up the use of platform specific header files here,
with the goal of turning more of the platforms over to being
"multiplatform" enabled, which implies that they cannot expose their
headers to architecture independent code any more.
It is expected that no functional changes are part of the cleanup.
The overall reduction in total code lines is mostly the result of
removing broken and obsolete code."
* tag 'cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (133 commits)
ARM: mvebu: correct gated clock documentation
ARM: kirkwood: add missing include for nsa310
ARM: exynos: move exynos4210-combiner to drivers/irqchip
mfd: db8500-prcmu: update resource passing
drivers/db8500-cpufreq: delete dangling include
ARM: at91: remove NEOCORE 926 board
sunxi: Cleanup the reset code and add meaningful registers defines
ARM: S3C24XX: header mach/regs-mem.h local
ARM: S3C24XX: header mach/regs-power.h local
ARM: S3C24XX: header mach/regs-s3c2412-mem.h local
ARM: S3C24XX: Remove plat-s3c24xx directory in arch/arm/
ARM: S3C24XX: transform s3c2443 subirqs into new structure
ARM: S3C24XX: modify s3c2443 irq init to initialize all irqs
ARM: S3C24XX: move s3c2443 irq code to irq.c
ARM: S3C24XX: transform s3c2416 irqs into new structure
ARM: S3C24XX: modify s3c2416 irq init to initialize all irqs
ARM: S3C24XX: move s3c2416 irq init to common irq code
ARM: S3C24XX: Modify s3c_irq_wake to use the hwirq property
ARM: S3C24XX: Move irq syscore-ops to irq-pm
clocksource: always define CLOCKSOURCE_OF_DECLARE
...
Pull timer changes from Ingo Molnar:
"Main changes:
- ntp: Add CONFIG_RTC_SYSTOHC: a generic RTC driver facility
complementing the existing CONFIG_RTC_HCTOSYS, which uses NTP to
keep the hardware clock updated.
- posix-timers: Fix clock_adjtime to always return timex data on
success. This is changing the ABI, but no breakage was expected
and found - caution is warranted nevertheless.
- platform persistent clock improvements/cleanups.
- clockevents: refactor timer broadcast handling to be more generic
and less duplicated with matching architecture code (mostly ARM
motivated.)
- various fixes and cleanups"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timers/x86/hpet: Use HPET_COUNTER to specify the hpet counter in vread_hpet()
posix-cpu-timers: Fix nanosleep task_struct leak
clockevents: Fix generic broadcast for FEAT_C3STOP
time, Fix setting of hardware clock in NTP code
hrtimer: Prevent hrtimer_enqueue_reprogram race
clockevents: Add generic timer broadcast function
clockevents: Add generic timer broadcast receiver
timekeeping: Switch HAS_PERSISTENT_CLOCK to ALWAYS_USE_PERSISTENT_CLOCK
x86/time/rtc: Don't print extended CMOS year when reading RTC
x86: Select HAS_PERSISTENT_CLOCK on x86
timekeeping: Add CONFIG_HAS_PERSISTENT_CLOCK option
rtc: Skip the suspend/resume handling if persistent clock exist
timekeeping: Add persistent_clock_exist flag
posix-timers: Fix clock_adjtime to always return timex data on success
Round the calculated scale factor in set_cyc2ns_scale()
NTP: Add a CONFIG_RTC_SYSTOHC configuration
MAINTAINERS: Update John Stultz's email
time: create __getnstimeofday for WARNless calls
Pull scheduler changes from Ingo Molnar:
"Main changes:
- scheduler side full-dynticks (user-space execution is undisturbed
and receives no timer IRQs) preparation changes that convert the
cputime accounting code to be full-dynticks ready, from Frederic
Weisbecker.
- Initial sched.h split-up changes, by Clark Williams
- select_idle_sibling() performance improvement by Mike Galbraith:
" 1 tbench pair (worst case) in a 10 core + SMT package:
pre 15.22 MB/sec 1 procs
post 252.01 MB/sec 1 procs "
- sched_rr_get_interval() ABI fix/change. We think this detail is not
used by apps (so it's not an ABI in practice), but lets keep it
under observation.
- misc RT scheduling cleanups, optimizations"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
sched/rt: Add <linux/sched/rt.h> header to <linux/init_task.h>
cputime: Remove irqsave from seqlock readers
sched, powerpc: Fix sched.h split-up build failure
cputime: Restore CPU_ACCOUNTING config defaults for PPC64
sched/rt: Move rt specific bits into new header file
sched/rt: Add a tuning knob to allow changing SCHED_RR timeslice
sched: Move sched.h sysctl bits into separate header
sched: Fix signedness bug in yield_to()
sched: Fix select_idle_sibling() bouncing cow syndrome
sched/rt: Further simplify pick_rt_task()
sched/rt: Do not account zero delta_exec in update_curr_rt()
cputime: Safely read cputime of full dynticks CPUs
kvm: Prepare to add generic guest entry/exit callbacks
cputime: Use accessors to read task cputime stats
cputime: Allow dynamic switch between tick/virtual based cputime accounting
cputime: Generic on-demand virtual cputime accounting
cputime: Move default nsecs_to_cputime() to jiffies based cputime file
cputime: Librarize per nsecs resolution cputime definitions
cputime: Avoid multiplication overflow on utime scaling
context_tracking: Export context state for generic vtime
...
Fix up conflict in kernel/context_tracking.c due to comment additions.
seconds_overflow() is called from hard interrupt context even on
Preempt-RT. This requires the lock to be a raw_spinlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 12ad100046: "clockevents: Add generic timer broadcast function"
made tick_device_uses_broadcast set up the generic broadcast function
for dummy devices (where !tick_device_is_functional(dev)), but neglected
to set up the broadcast function for devices that stop in low power
states (with the CLOCK_EVT_FEAT_C3STOP flag).
When these devices enter low power states they will not have the generic
broadcast function assigned, and will bring down the system when an
attempt is made to broadcast to them.
This patch ensures that the broadcast function is also assigned for
devices which require broadcast in low power states.
Reported-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: nico@linaro.org
Cc: Marc.Zyngier@arm.com
Cc: Will.Deacon@arm.com
Cc: santosh.shilimkar@ti.com
Cc: john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
At init time, if the system time is "warped" forward in warp_clock()
it will differ from the hardware clock by sys_tz.tz_minuteswest. This time
difference is not taken into account when ntp updates the hardware clock,
and this causes the system time to jump forward by this offset every reboot.
The kernel must take this offset into account when writing the system time
to the hardware clock in the ntp code. This patch adds
persistent_clock_is_local which indicates that an offset has been applied
in warp_clock() and accounts for the "warp" before writing the hardware
clock.
x86 does not have this problem as rtc writes are software limited to a
+/-15 minute window relative to the current rtc time. Other arches, such
as powerpc, however do a full synchronization of the system time to the
rtc and will see this problem.
[v2]: generated against tip/timers/core
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Conflicts:
kernel/irq_work.c
Add support for printk in full dynticks CPU.
* Don't stop tick with irq works pending. This
fix is generally useful and concerns archs that
can't raise self IPIs.
* Flush irq works before CPU offlining.
* Introduce "lazy" irq works that can wait for the
next tick to be executed, unless it's stopped.
* Implement klogd wake up using irq work. This
removes the ad-hoc printk_tick()/printk_needs_cpu()
hooks and make it working even in dynticks mode.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Currently, the timer broadcast mechanism is defined by a function
pointer on struct clock_event_device. As the fundamental mechanism for
broadcast is architecture-specific, this means that clock_event_device
drivers cannot be shared across multiple architectures.
This patch adds an (optional) architecture-specific function for timer
tick broadcast, allowing drivers which may require broadcast
functionality to be shared across multiple architectures.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: nico@linaro.org
Cc: Will.Deacon@arm.com
Cc: Marc.Zyngier@arm.com
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1358183124-28461-3-git-send-email-mark.rutland@arm.com
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently the broadcast mechanism used for timers is abstracted by a
function pointer on struct clock_event_device. As the fundamental
mechanism for broadcast is architecture-specific, this ties each
clock_event_device driver to a single architecture, even where the
driver is otherwise generic.
This patch adds a standard path for the receipt of timer broadcasts, so
drivers and/or architecture backends need not manage redundant lists of
timers for the purpose of routing broadcast timer ticks.
[tglx: Made the implementation depend on the config switch as well ]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: nico@linaro.org
Cc: Will.Deacon@arm.com
Cc: Marc.Zyngier@arm.com
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1358183124-28461-2-git-send-email-mark.rutland@arm.com
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Jason pointed out the HAS_PERSISTENT_CLOCK name isn't
quite accurate for the config, as some systems may have
the persistent_clock in some cases, but not always.
So change the config name to the more clear
ALWAYS_USE_PERSISTENT_CLOCK.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Allow to dynamically switch between tick and virtual based
cputime accounting. This way we can provide a kind of "on-demand"
virtual based cputime accounting. In this mode, the kernel relies
on the context tracking subsystem to dynamically probe on kernel
boundaries.
This is in preparation for being able to stop the timer tick in
more places than just the idle state. Doing so will depend on
CONFIG_VIRT_CPU_ACCOUNTING_GEN which makes it possible to account
the cputime without the tick by hooking on kernel/user boundaries.
Depending whether the tick is stopped or not, we can switch between
tick and vtime based accounting anytime in order to minimize the
overhead associated to user hooks.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Allow drivers such as intel_powerclamp to use these apis for
turning on/off ticks during idle.
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Make the persistent clock check a kernel config option, so that some
platform can explicitely select it, also make CONFIG_RTC_HCTOSYS and
RTC_SYSTOHC depend on its non-existence, which could prevent the
persistent clock and RTC code from doing similar thing twice during
system's init/suspend/resume phases.
If the CONFIG_HAS_PERSISTENT_CLOCK=n, then no change happens for kernel
which still does the persistent clock check in timekeeping_init().
Cc: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Feng Tang <feng.tang@intel.com>
[jstultz: Added dependency for RTC_SYSTOHC as well]
Signed-off-by: John Stultz <john.stultz@linaro.org>
In current kernel, there are several places which need to check
whether there is a persistent clock for the platform. Current check
is done by calling the read_persistent_clock() and validating its
return value.
So one optimization is to do the check only once in timekeeping_init(),
and use a flag persistent_clock_exist to record it.
v2: Add a has_persistent_clock() helper function, as suggested by John.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The purpose of this option is to allow ARM/etc systems that rely on the
class RTC subsystem to have the same kind of automatic NTP based
synchronization that we have on PC platforms. Today ARM does not
implement update_persistent_clock and makes extensive use of the class
RTC system.
When enabled CONFIG_RTC_SYSTOHC will provide a generic
rtc_update_persistent_clock that stores the current time in the RTC and
is intended complement the existing CONFIG_RTC_HCTOSYS option that loads
the RTC at boot.
Like with RTC_HCTOSYS the platform's update_persistent_clock is used
first, if it works. Platforms with mixed class RTC and non-RTC drivers
need to return ENODEV when class RTC should be used. Such an update for
PPC is included in this patch.
Long term, implementations of update_persistent_clock should migrate to
proper class RTC drivers and use CONFIG_RTC_SYSTOHC instead.
Tested on ARM kirkwood and PPC405
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The pstore RAM backend can get called during resume, and must be defensive
against a suspended time source. Expose getnstimeofday logic that returns
an error instead of a WARN. This can be detected and the timestamp can
be zeroed out.
Reported-by: Doug Anderson <dianders@chromium.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Clockevent cleanup series from Shawn Guo.
Resolved move/change conflict in mach-pxa/time.c due to the sys_timer
cleanup.
* clocksource/cleanup:
clocksource: use clockevents_config_and_register() where possible
ARM: use clockevents_config_and_register() where possible
clockevents: export clockevents_config_and_register for module use
+ sync to Linux 3.8-rc3
Signed-off-by: Olof Johansson <olof@lixom.net>
Conflicts:
arch/arm/mach-pxa/time.c
clockevents_config_and_register is a handy helper for clockevent
drivers, some of which might support module build, so export the symbol.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Olof Johansson <olof@lixom.net>
Currently, whenever CONFIG_ARCH_USES_GETTIMEOFFSET is enabled, each
arch core provides a single implementation of arch_gettimeoffset(). In
many cases, different sub-architectures, different machines, or
different timer providers exist, and so the arch ends up implementing
arch_gettimeoffset() as a call-through-pointer anyway. Examples are
ARM, Cris, M68K, and it's arguable that the remaining architectures,
M32R and Blackfin, should be doing this anyway.
Modify arch_gettimeoffset so that it itself is a function pointer, which
the arch initializes. This will allow later changes to move the
initialization of this function into individual machine support or timer
drivers. This is particularly useful for code in drivers/clocksource
which should rely on an arch-independant mechanism to register their
implementation of arch_gettimeoffset().
This patch also converts the Cris architecture to set arch_gettimeoffset
directly to the final implementation in time_init(), because Cris already
had separate time_init() functions per sub-architecture. M68K and ARM
are converted to set arch_gettimeoffset to the final implementation in
later patches, because they already have function pointers in place for
this purpose.
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Pull KVM updates from Marcelo Tosatti:
"Considerable KVM/PPC work, x86 kvmclock vsyscall support,
IA32_TSC_ADJUST MSR emulation, amongst others."
Fix up trivial conflict in kernel/sched/core.c due to cross-cpu
migration notifier added next to rq migration call-back.
* tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (156 commits)
KVM: emulator: fix real mode segment checks in address linearization
VMX: remove unneeded enable_unrestricted_guest check
KVM: VMX: fix DPL during entry to protected mode
x86/kexec: crash_vmclear_local_vmcss needs __rcu
kvm: Fix irqfd resampler list walk
KVM: VMX: provide the vmclear function and a bitmap to support VMCLEAR in kdump
x86/kexec: VMCLEAR VMCSs loaded on all cpus if necessary
KVM: MMU: optimize for set_spte
KVM: PPC: booke: Get/set guest EPCR register using ONE_REG interface
KVM: PPC: bookehv: Add EPCR support in mtspr/mfspr emulation
KVM: PPC: bookehv: Add guest computation mode for irq delivery
KVM: PPC: Make EPCR a valid field for booke64 and bookehv
KVM: PPC: booke: Extend MAS2 EPN mask for 64-bit
KVM: PPC: e500: Mask MAS2 EPN high 32-bits in 32/64 tlbwe emulation
KVM: PPC: Mask ea's high 32-bits in 32/64 instr emulation
KVM: PPC: e500: Add emulation helper for getting instruction ea
KVM: PPC: bookehv64: Add support for interrupt handling
KVM: PPC: bookehv: Remove GET_VCPU macro from exception handler
KVM: PPC: booke: Fix get_tb() compile error on 64-bit
KVM: PPC: e500: Silence bogus GCC warning in tlb code
...
Pull networking changes from David Miller:
1) Allow to dump, monitor, and change the bridge multicast database
using netlink. From Cong Wang.
2) RFC 5961 TCP blind data injection attack mitigation, from Eric
Dumazet.
3) Networking user namespace support from Eric W. Biederman.
4) tuntap/virtio-net multiqueue support by Jason Wang.
5) Support for checksum offload of encapsulated packets (basically,
tunneled traffic can still be checksummed by HW). From Joseph
Gasparakis.
6) Allow BPF filter access to VLAN tags, from Eric Dumazet and
Daniel Borkmann.
7) Bridge port parameters over netlink and BPDU blocking support
from Stephen Hemminger.
8) Improve data access patterns during inet socket demux by rearranging
socket layout, from Eric Dumazet.
9) TIPC protocol updates and cleanups from Ying Xue, Paul Gortmaker, and
Jon Maloy.
10) Update TCP socket hash sizing to be more in line with current day
realities. The existing heurstics were choosen a decade ago.
From Eric Dumazet.
11) Fix races, queue bloat, and excessive wakeups in ATM and
associated drivers, from Krzysztof Mazur and David Woodhouse.
12) Support DOVE (Distributed Overlay Virtual Ethernet) extensions
in VXLAN driver, from David Stevens.
13) Add "oops_only" mode to netconsole, from Amerigo Wang.
14) Support set and query of VEB/VEPA bridge mode via PF_BRIDGE, also
allow DCB netlink to work on namespaces other than the initial
namespace. From John Fastabend.
15) Support PTP in the Tigon3 driver, from Matt Carlson.
16) tun/vhost zero copy fixes and improvements, plus turn it on
by default, from Michael S. Tsirkin.
17) Support per-association statistics in SCTP, from Michele
Baldessari.
And many, many, driver updates, cleanups, and improvements. Too
numerous to mention individually.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1722 commits)
net/mlx4_en: Add support for destination MAC in steering rules
net/mlx4_en: Use generic etherdevice.h functions.
net: ethtool: Add destination MAC address to flow steering API
bridge: add support of adding and deleting mdb entries
bridge: notify mdb changes via netlink
ndisc: Unexport ndisc_{build,send}_skb().
uapi: add missing netconf.h to export list
pkt_sched: avoid requeues if possible
solos-pci: fix double-free of TX skb in DMA mode
bnx2: Fix accidental reversions.
bna: Driver Version Updated to 3.1.2.1
bna: Firmware update
bna: Add RX State
bna: Rx Page Based Allocation
bna: TX Intr Coalescing Fix
bna: Tx and Rx Optimizations
bna: Code Cleanup and Enhancements
ath9k: check pdata variable before dereferencing it
ath5k: RX timestamp is reported at end of frame
ath9k_htc: RX timestamp is reported at end of frame
...
Pull core timer changes from Ingo Molnar:
"It contains continued generic-NOHZ work by Frederic and smaller
cleanups."
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Kill xtime_lock, replacing it with jiffies_lock
clocksource: arm_generic: use this_cpu_ptr per-cpu helper
clocksource: arm_generic: use integer math helpers
time/jiffies: Make clocksource_jiffies static
clocksource: clean up parse_pmtmr()
tick: Correct the comments for tick_sched_timer()
tick: Conditionally build nohz specific code in tick handler
tick: Consolidate tick handling for high and low res handlers
tick: Consolidate timekeeping handling code
Pull trivial fix branches from Ingo Molnar.
Cleanup in __get_key_name, and a timer comment fixlet.
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Use KSYM_NAME_LEN'ed buffer for __get_key_name()
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timers, sched: Correct the comments for tick_sched_timer()
As suggested by John, export time data similarly to how its
done by vsyscall support. This allows KVM to retrieve necessary
information to implement vsyscall support in KVM guests.
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
klogd is woken up asynchronously from the tick in order
to do it safely.
However if printk is called when the tick is stopped, the reader
won't be woken up until the next interrupt, which might not fire
for a while. As a result, the user may miss some message.
To fix this, lets implement the printk tick using a lazy irq work.
This subsystem takes care of the timer tick state and can
fix up accordingly.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Don't stop the tick if we have pending irq works on the
queue, otherwise if the arch can't raise self-IPIs, we may not
find an opportunity to execute the pending works for a while.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
We need some quick way to check if the CPU has stopped
its tick. This will be useful to implement the printk tick
using the irq work subsystem.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
The prediction for future is difficult and when the cpuidle governor prediction
fails and govenor possibly choose the shallower C-state than it should. How to
quickly notice and find the failure becomes important for power saving.
cpuidle menu governor has a method to predict the repeat pattern if there are 8
C-states residency which are continuous and the same or very close, so it will
predict the next C-states residency will keep same residency time.
There is a real case that turbostat utility (tools/power/x86/turbostat)
at kernel 3.3 or early. turbostat utility will read 10 registers one by one at
Sandybridge, so it will generate 10 IPIs to wake up idle CPUs. So cpuidle menu
governor will predict it is repeat mode and there is another IPI wake up idle
CPU soon, so it keeps idle CPU stay at C1 state even though CPU is totally
idle. However, in the turbostat, following 10 registers reading is sleep 5
seconds by default, so the idle CPU will keep at C1 for a long time though it is
idle until break event occurs.
In a idle Sandybridge system, run "./turbostat -v", we will notice that deep
C-state dangles between "70% ~ 99%". After patched the kernel, we will notice
deep C-state stays at >99.98%.
In the patch, a timer is added when menu governor detects a repeat mode and
choose a shallow C-state. The timer is set to a time out value that greater
than predicted time, and we conclude repeat mode prediction failure if timer is
triggered. When repeat mode happens as expected, the timer is not triggered
and CPU waken up from C-states and it will cancel the timer initiatively.
When repeat mode does not happen, the timer will be time out and menu governor
will quickly notice that the repeat mode prediction fails and then re-evaluates
deeper C-states possibility.
Below is another case which will clearly show the patch much benefit:
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/time.h>
#include <time.h>
#include <pthread.h>
volatile int * shutdown;
volatile long * count;
int delay = 20;
int loop = 8;
void usage(void)
{
fprintf(stderr,
"Usage: idle_predict [options]\n"
" --help -h Print this help\n"
" --thread -n Thread number\n"
" --loop -l Loop times in shallow Cstate\n"
" --delay -t Sleep time (uS)in shallow Cstate\n");
}
void *simple_loop() {
int idle_num = 1;
while (!(*shutdown)) {
*count = *count + 1;
if (idle_num % loop)
usleep(delay);
else {
/* sleep 1 second */
usleep(1000000);
idle_num = 0;
}
idle_num++;
}
}
static void sighand(int sig)
{
*shutdown = 1;
}
int main(int argc, char *argv[])
{
sigset_t sigset;
int signum = SIGALRM;
int i, c, er = 0, thread_num = 8;
pthread_t pt[1024];
static char optstr[] = "n:l:t:h:";
while ((c = getopt(argc, argv, optstr)) != EOF)
switch (c) {
case 'n':
thread_num = atoi(optarg);
break;
case 'l':
loop = atoi(optarg);
break;
case 't':
delay = atoi(optarg);
break;
case 'h':
default:
usage();
exit(1);
}
printf("thread=%d,loop=%d,delay=%d\n",thread_num,loop,delay);
count = malloc(sizeof(long));
shutdown = malloc(sizeof(int));
*count = 0;
*shutdown = 0;
sigemptyset(&sigset);
sigaddset(&sigset, signum);
sigprocmask (SIG_BLOCK, &sigset, NULL);
signal(SIGINT, sighand);
signal(SIGTERM, sighand);
for(i = 0; i < thread_num ; i++)
pthread_create(&pt[i], NULL, simple_loop, NULL);
for (i = 0; i < thread_num; i++)
pthread_join(pt[i], NULL);
exit(0);
}
Get powertop V2 from git://github.com/fenrus75/powertop, build powertop.
After build the above test application, then run it.
Test plaform can be Intel Sandybridge or other recent platforms.
#./idle_predict -l 10 &
#./powertop
We will find that deep C-state will dangle between 40%~100% and much time spent
on C1 state. It is because menu governor wrongly predict that repeat mode
is kept, so it will choose the C1 shallow C-state even though it has chance to
sleep 1 second in deep C-state.
While after patched the kernel, we find that deep C-state will keep >99.6%.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Now that timekeeping is protected by its own locks, rename
the xtime_lock to jifffies_lock to better describe what it
protects.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Commit f1b8274 ("clocksource: Cleanup clocksource selection") removed all
external references to clocksource_jiffies so there is no need to have the
symbol globally visible.
Fixes the following sparse warning:
CHECK kernel/time/jiffies.c kernel/time/jiffies.c:61:20: warning: symbol 'clocksource_jiffies' was not declared. Should it be static?
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This patch removes the timecompare code from the kernel. The top five
reasons to do this are:
1. There are no more users of this code.
2. The original idea was a bit weak.
3. The original author has disappeared.
4. The code was not general purpose but tuned to a particular hardware,
5. There are better ways to accomplish clock synchronization.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Tested-by: Bob Liu <lliubbo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the comments of function tick_sched_timer(), the sentence
"timer->base->cpu_base->lock held" is not right.
In function __run_hrtimer(), before call timer->function(),
the cpu_base->lock has been unlocked.
Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Cc: fei.li@intel.com
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1351098455.15558.1421.camel@cliu38-desktop-build
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In the comments of function tick_sched_timer(), the sentence
"timer->base->cpu_base->lock held" is not right.
In function __run_hrtimer(), before call timer->function(),
the cpu_base->lock has been unlocked.
Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Cc: fei.li@intel.com
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1351098455.15558.1421.camel@cliu38-desktop-build
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This optimize a bit the high res tick sched handler.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Besides unifying code, this also adds the idle check before
processing idle accounting specifics on the low res handler.
This way we also generalize this part of the nohz code for
!CONFIG_HIGH_RES_TIMERS to prepare for the adaptive tickless
features.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Unify the duplicated timekeeping handling code of low and high res tick
sched handlers.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Pull timer core update from Thomas Gleixner:
- Bug fixes (one for a longstanding dead loop issue)
- Rework of time related vsyscalls
- Alarm timer updates
- Jiffies updates to remove compile time dependencies
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Cast raw_interval to u64 to avoid shift overflow
timers: Fix endless looping between cascade() and internal_add_timer()
time/jiffies: bring back unconditional LATCH definition
time: Convert x86_64 to using new update_vsyscall
time: Only do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD systems
time: Introduce new GENERIC_TIME_VSYSCALL
time: Convert CONFIG_GENERIC_TIME_VSYSCALL to CONFIG_GENERIC_TIME_VSYSCALL_OLD
time: Move update_vsyscall definitions to timekeeper_internal.h
time: Move timekeeper structure to timekeeper_internal.h for vsyscall changes
jiffies: Remove compile time assumptions about CLOCK_TICK_RATE
jiffies: Kill unused TICK_USEC_TO_NSEC
alarmtimer: Rename alarmtimer_remove to alarmtimer_dequeue
alarmtimer: Remove unused helpers & defines
alarmtimer: Use hrtimer per-alarm instead of per-base
alarmtimer: Implement minimum alarm interval for allowing suspend
Pull scheduler fixes from Ingo Molnar:
"A CPU hotplug related crash fix and a nohz accounting fixlet."
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Update sched_domains_numa_masks[][] when new cpus are onlined
sched: Ensure 'sched_domains_numa_levels' is safe to use in other functions
nohz: Fix one jiffy count too far in idle cputime
We fixed a bunch of integer overflows in timekeeping code during the 3.6
cycle. I did an audit based on that and found this potential overflow.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20121009071823.GA19159@elgon.mountain
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
When we stop the tick in idle, we save the current jiffies value
in ts->idle_jiffies. This snapshot is substracted from the later
value of jiffies when the tick is restarted and the resulting
delta is accounted as idle cputime. This is how we handle the
idle cputime accounting without the tick.
But sometimes we need to schedule the next tick to some time in
the future instead of completely stopping it. In this case, a
tick may happen before we restart the periodic behaviour and
from that tick we account one jiffy to idle cputime as usual but
we also increment the ts->idle_jiffies snapshot by one so that
when we compute the delta to account, we substract the one jiffy
we just accounted.
To prepare for stopping the tick outside idle, we introduced a
check that prevents from fixing up that ts->idle_jiffies if we
are not running the idle task. But we use idle_cpu() for that
and this is a problem if we run the tick while another CPU
remotely enqueues a ttwu to our runqueue:
CPU 0: CPU 1:
tick_sched_timer() { ttwu_queue_remote()
if (idle_cpu(CPU 0))
ts->idle_jiffies++;
}
Here, idle_cpu() notes that &rq->wake_list is not empty and
hence won't consider the CPU as idle. As a result,
ts->idle_jiffies won't be incremented. But this is wrong because
we actually account the current jiffy to idle cputime. And that
jiffy won't get substracted from the nohz time delta. So in the
end, this jiffy is accounted twice.
Fix this by changing idle_cpu(smp_processor_id()) with
is_idle_task(current). This way the jiffy is substracted
correctly even if a ttwu operation is enqueued on the CPU.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # 3.5+
Link: http://lkml.kernel.org/r/1349308004-3482-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Improved system suspend/resume and runtime PM handling for the SH TMU, CMT
and MTU2 clock event devices (also used by ARM/shmobile).
* Generic PM domains framework extensions related to cpuidle support and
domain objects lookup using names.
* ARM/shmobile power management updates including improved support for the
SH7372's A4S power domain containing the CPU core.
* cpufreq changes related to AMD CPUs support from Matthew Garrett, Andre
Przywara and Borislav Petkov.
* cpu0 cpufreq driver from Shawn Guo.
* cpufreq governor fixes related to the relaxing of limit from Michal Pecio.
* OMAP cpufreq updates from Axel Lin and Richard Zhao.
* cpuidle ladder governor fixes related to the disabling of states from
Carsten Emde and me.
* Runtime PM core updates related to the interactions with the system suspend
core from Alan Stern and Kevin Hilman.
* Wakeup sources modification allowing more helper functions to be called from
interrupt context from John Stultz and additional diagnostic code from Todd
Poynor.
* System suspend error code path fix from Feng Hong.
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Merge tag 'pm-for-3.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael J Wysocki:
- Improved system suspend/resume and runtime PM handling for the SH
TMU, CMT and MTU2 clock event devices (also used by ARM/shmobile).
- Generic PM domains framework extensions related to cpuidle support
and domain objects lookup using names.
- ARM/shmobile power management updates including improved support for
the SH7372's A4S power domain containing the CPU core.
- cpufreq changes related to AMD CPUs support from Matthew Garrett,
Andre Przywara and Borislav Petkov.
- cpu0 cpufreq driver from Shawn Guo.
- cpufreq governor fixes related to the relaxing of limit from Michal
Pecio.
- OMAP cpufreq updates from Axel Lin and Richard Zhao.
- cpuidle ladder governor fixes related to the disabling of states from
Carsten Emde and me.
- Runtime PM core updates related to the interactions with the system
suspend core from Alan Stern and Kevin Hilman.
- Wakeup sources modification allowing more helper functions to be
called from interrupt context from John Stultz and additional
diagnostic code from Todd Poynor.
- System suspend error code path fix from Feng Hong.
Fixed up conflicts in cpufreq/powernow-k8 that stemmed from the
workqueue fixes conflicting fairly badly with the removal of support for
hardware P-state chips. The changes were independent but somewhat
intertwined.
* tag 'pm-for-3.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (76 commits)
Revert "PM QoS: Use spinlock in the per-device PM QoS constraints code"
PM / Runtime: let rpm_resume() succeed if RPM_ACTIVE, even when disabled, v2
cpuidle: rename function name "__cpuidle_register_driver", v2
cpufreq: OMAP: Check IS_ERR() instead of NULL for omap_device_get_by_hwmod_name
cpuidle: remove some empty lines
PM: Prevent runtime suspend during system resume
PM QoS: Use spinlock in the per-device PM QoS constraints code
PM / Sleep: use resume event when call dpm_resume_early
cpuidle / ACPI : move cpuidle_device field out of the acpi_processor_power structure
ACPI / processor: remove pointless variable initialization
ACPI / processor: remove unused function parameter
cpufreq: OMAP: remove loops_per_jiffy recalculate for smp
sections: fix section conflicts in drivers/cpufreq
cpufreq: conservative: update frequency when limits are relaxed
cpufreq / ondemand: update frequency when limits are relaxed
properly __init-annotate pm_sysrq_init()
cpufreq: Add a generic cpufreq-cpu0 driver
PM / OPP: Initialize OPP table from device tree
ARM: add cpufreq transiton notifier to adjust loops_per_jiffy for smp
cpufreq: Remove support for hardware P-state chips from powernow-k8
...
Pull scheduler changes from Ingo Molnar:
"Continued quest to clean up and enhance the cputime code by Frederic
Weisbecker, in preparation for future tickless kernel features.
Other than that, smallish changes."
Fix up trivial conflicts due to additions next to each other in arch/{x86/}Kconfig
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
cputime: Make finegrained irqtime accounting generally available
cputime: Gather time/stats accounting config options into a single menu
ia64: Reuse system and user vtime accounting functions on task switch
ia64: Consolidate user vtime accounting
vtime: Consolidate system/idle context detection
cputime: Use a proper subsystem naming for vtime related APIs
sched: cpu_power: enable ARCH_POWER
sched/nohz: Clean up select_nohz_load_balancer()
sched: Fix load avg vs. cpu-hotplug
sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW
sched: Fix nohz_idle_balance()
sched: Remove useless code in yield_to()
sched: Add time unit suffix to sched sysctl knobs
sched/debug: Limit sd->*_idx range on sysctl
sched: Remove AFFINE_WAKEUPS feature flag
s390: Remove leftover account_tick_vtime() header
cputime: Consolidate vtime handling on context switch
sched: Move cputime code to its own file
cputime: Generalize CONFIG_VIRT_CPU_ACCOUNTING
tile: Remove SD_PREFER_LOCAL leftover
...
We only do rounding to the next nanosecond so we don't see minor
1ns inconsistencies in the vsyscall implementations. Since we're
changing the vsyscall implementations to avoid this, conditionalize
the rounding only to the GENERIC_TIME_VSYSCALL_OLD architectures.
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Now that we moved everyone over to GENERIC_TIME_VSYSCALL_OLD,
introduce the new declaration and config option for the new
update_vsyscall method.
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
To help migrate archtectures over to the new update_vsyscall method,
redfine CONFIG_GENERIC_TIME_VSYSCALL as CONFIG_GENERIC_TIME_VSYSCALL_OLD
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
We're going to need to access the timekeeper in update_vsyscall,
so make the structure available for those who need it.
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
CLOCK_TICK_RATE is used to accurately caclulate exactly how
a tick will be at a given HZ.
This is useful, because while we'd expect NSEC_PER_SEC/HZ,
the underlying hardware will have some granularity limit,
so we won't be able to have exactly HZ ticks per second.
This slight error can cause timekeeping quality problems
when using the jiffies or other jiffies driven clocksources.
Thus we currently use compile time CLOCK_TICK_RATE value to
generate SHIFTED_HZ and NSEC_PER_JIFFIES, which we then use
to adjust the jiffies clocksource to correct this error.
Unfortunately though, since CLOCK_TICK_RATE is a compile
time value, and the jiffies clocksource is registered very
early during boot, there are a number of cases where there
are different possible hardware timers that have different
tick rates. This causes problems in cases like ARM where
there are numerous different types of hardware, each having
their own compile-time CLOCK_TICK_RATE, making it hard to
accurately support different hardware with a single kernel.
For the most part, this doesn't matter all that much, as not
too many systems actually utilize the jiffies or jiffies driven
clocksource. Usually there are other highres clocksources
who's granularity error is negligable.
Even so, we have some complicated calcualtions that we do
everywhere to handle these edge cases.
This patch removes the compile time SHIFTED_HZ value, and
introduces a register_refined_jiffies() function. This results
in the default jiffies clock as being assumed a perfect HZ
freq, and allows archtectures that care about jiffies accuracy
to call register_refined_jiffies() with the tick rate, specified
dynamically at boot.
This allows us, where necessary, to not have a compile time
CLOCK_TICK_RATE constant, simplifies the jiffies code, and
still provides a way to have an accurate jiffies clock.
NOTE: Since this patch does not add register_refinied_jiffies()
calls for every arch, it may cause time quality regressions
in some cases. Its likely these will not be noticable, but
if they are an issue, adding the following to the end of
setup_arch() should resolve the regression:
register_refinied_jiffies(CLOCK_TICK_RATE)
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Now that alarmtimer_remove has been simplified, change
its name to _dequeue to better match its paired _enqueue
function.
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Arve Hjønnevåg reported numerous crashes from the
"BUG_ON(timer->state != HRTIMER_STATE_CALLBACK)" check
in __run_hrtimer after it called alarmtimer_fired.
It ends up the alarmtimer code was not properly handling
possible failures of hrtimer_try_to_cancel, and because
these faulres occur when the underlying base hrtimer is
being run, this limits the ability to properly handle
modifications to any alarmtimers on that base.
Because much of the logic duplicates the hrtimer logic,
it seems that we might as well have a per-alarmtimer
hrtimer, and avoid the extra complextity of trying to
multiplex many alarmtimers off of one hrtimer.
Thus this patch moves the hrtimer to the alarm structure
and simplifies the management logic.
Changelog:
v2:
* Includes a fix for double alarm_start calls found by
Arve
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Arve Hjønnevåg <arve@android.com>
Tested-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
alarmtimer suspend return -EBUSY if the next alarm will fire in less
than 2 seconds. This allows one RTC seconds tick to occur subsequent
to this check before the alarm wakeup time is set, ensuring the wakeup
time is still in the future (assuming the RTC does not tick one more
second prior to setting the alarm).
If suspend is rejected due to an imminent alarm, hold a wakeup source
for 2 seconds to process the alarm prior to reattempting suspend.
If setting the alarm incurs an -ETIME for an alarm set in the past,
or any other problem setting the alarm, abort suspend and hold a
wakelock for 1 second while the alarm is allowed to be serviced or
other hopefully transient conditions preventing the alarm clear up.
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The can_stop_idle_tick() function complains if a softirq vector is
raised too late in the idle-entry process, presumably in order to
prevent dangling softirq invocations from being delayed across the
full idle period, which might be indefinitely long -- and if softirq
was asserted any later than the call to this function, such a delay
might well happen.
However, RCU needs to be able to use softirq to stop idle entry in
order to be able to drain RCU callbacks from the current CPU, which in
turn enables faster entry into dyntick-idle mode, which in turn reduces
power consumption. Because RCU takes this action at a well-defined
point in the idle-entry path, it is safe for RCU to take this approach.
This commit therefore silences the error message that is sometimes
produced when the going-idle CPU suddenly finds that it has an RCU_SOFTIRQ
to process. The error message will continue to be issued for other
softirq vectors.
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Pull timer fix from Ingo Molnar:
"One more timekeeping fix for v3.6"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Fix timeekeping_get_ns overflow on 32bit systems
* pm-timers:
PM: Do not use the syscore flag for runtime PM
sh: MTU2: Basic runtime PM support
sh: CMT: Basic runtime PM support
sh: TMU: Basic runtime PM support
PM / Domains: Do not measure start time for "irq safe" devices
PM / Domains: Move syscore flag from subsys data to struct device
PM / Domains: Rename the always_on device flag to syscore
PM / Runtime: Allow helpers to be called by early platform drivers
PM: Reorganize device PM initialization
sh: MTU2: Introduce clock events suspend/resume routines
sh: CMT: Introduce clocksource/clock events suspend/resume routines
sh: TMU: Introduce clocksource/clock events suspend/resume routines
timekeeping: Add suspend and resume of clock event devices
PM / Domains: Add power off/on function for system core suspend stage
PM / Domains: Introduce simplified power on routine for system resume
Daniel Lezcano reported seeing multi-second stalls from
keyboard input on his T61 laptop when NOHZ and CPU_IDLE
were enabled on a 32bit kernel.
He bisected the problem down to commit
1e75fa8be9 ("time: Condense timekeeper.xtime into xtime_sec").
After reproducing this issue, I narrowed the problem down
to the fact that timekeeping_get_ns() returns a 64bit
nsec value that hasn't been accumulated. In some cases
this value was being then stored in timespec.tv_nsec
(which is a long).
On 32bit systems, with idle times larger then 4 seconds
(or less, depending on the value of xtime_nsec), the
returned nsec value would overflow 32bits. This limited
kept time from increasing, causing timers to not expire.
The fix is to make sure we don't directly store the
result of timekeeping_get_ns() into a tv_nsec field,
instead using a 64bit nsec value which can then be
added into the timespec via timespec_add_ns().
Reported-and-bisected-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1347405963-35715-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no load_balancer to be selected now. It just sets the
state of the nohz tick to stop.
So rename the function, pass the 'cpu' as a parameter and then
remove the useless call from tick_nohz_restart_sched_tick().
[ s/set_nohz_tick_stopped/nohz_balance_enter_idle/g
s/clear_nohz_tick_stopped/nohz_balance_exit_idle/g ]
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347261059-24747-1-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Azat Khuzhin reported high loadavg in Linux v3.6
After checking the upstream scheduler code, I found Peter's commit:
5167e8d541 sched/nohz: Rewrite and fix load-avg computation -- again
not fully applied, missing the call to calc_load_exit_idle().
After that idle exit in sampling window will always be calculated
to non-idle, and the load will be higher than normal.
This patch adds the missing call to calc_load_exit_idle().
Signed-off-by: Charles Wang <muming.wq@taobao.com>
Cc: stable@kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1345449754-27130-1-git-send-email-muming.wq@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some clock event devices, for example such that belong to PM domains,
need to be handled in a spcial way during the timekeeping suspend
and resume (which takes place in the system core, or "syscore",
stages of system power transitions) in analogy with clock sources.
Introduce .suspend() and .resume() callbacks for clock event devices
that will be executed by timekeeping_suspend/_resume(), respectively,
next the the clock sources' .suspend() and .resume() callbacks.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Andreas Bombe reported that the added ktime_t overflow checking added to
timespec_valid in commit 4e8b14526c ("time: Improve sanity checking of
timekeeping inputs") was causing problems with X.org because it caused
timeouts larger then KTIME_T to be invalid.
Previously, these large timeouts would be clamped to KTIME_MAX and would
never expire, which is valid.
This patch splits the ktime_t overflow checking into a new
timespec_valid_strict function, and converts the timekeeping codes
internal checking to use this more strict function.
Reported-and-tested-by: Andreas Bombe <aeb@debian.org>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If update_wall_time() is called and the current offset isn't large
enough to accumulate, avoid re-calling timekeeping_adjust which may
change the clock freq and can cause 1ns inconsistencies with
CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Andreas Schwab noticed that the 1 << tk->shift could overflow if the
shift value was greater than 30, since 1 would be a 32bit long on
32bit architectures. This issue was introduced by 1e75fa8be (time:
Condense timekeeper.xtime into xtime_sec)
Use 1ULL instead to ensure we don't overflow on the shift.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
arch_gettimeoffset returns a u32 value which when shifted by tk->shift
can overflow. This issue was introduced with 1e75fa8be (time: Condense
timekeeper.xtime into xtime_sec)
Cast it to u64 first.
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Andreas noticed problems with resume on specific hardware after commit
1e75fa8b (time: Condense timekeeper.xtime into xtime_sec) combined
with commit b44d50dca (time: Fix casting issue in tk_set_xtime and
tk_xtime_add)
After some digging I realized we aren't normalizing the timekeeper
after the add. Add the missing normalize call.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Tested-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Unexpected behavior could occur if the time is set to a value large
enough to overflow a 64bit ktime_t (which is something larger then the
year 2262).
Also unexpected behavior could occur if large negative offsets are
injected via adjtimex.
So this patch improves the sanity check timekeeping inputs by
improving the timespec_valid() check, and then makes better use of
timespec_valid() to make sure we don't set the time to an invalid
negative value or one that overflows ktime_t.
Note: This does not protect from setting the time close to overflowing
ktime_t and then letting natural accumulation cause the overflow.
Reported-by: CAI Qian <caiqian@redhat.com>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tetsuo Handa reported that sporadically the system clock starts
counting up too quickly which is enough to confuse the hangcheck
timer to print a bogus stall warning.
Commit 2a8c0883 "time: Move xtime_nsec adjustment underflow handling
timekeeping_adjust" overlooked this exit path:
} else
return;
which should really be a proper exit sequence, fixing the bug as a
side effect.
Also make the flow more readable by properly balancing curly
braces.
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: john.stultz@linaro.org
Cc: a.p.zijlstra@chello.nl
Cc: richardcochran@gmail.com
Cc: prarit@redhat.com
Link: http://lkml.kernel.org/r/20120804192114.GA28347@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ingo noted that the numerous timekeeper.value references made
the timekeeping code ugly and caused many long lines that
had to be broken up. He recommended replacing timekeeper.value
references with tk->value.
This patch provides a local tk value for all top level time
functions and sets it to &timekeeper. Then all timekeeper
access is done via a tk pointer.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343414893-45779-6-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For performance reasons, we maintain ktime_t based duplicates of
wall_to_monotonic (offs_real) and total_sleep_time (offs_boot).
Since large problems could occur (such as the resume regression
on 3.5-rc7, or the leapsecond hrtimer issue) if these value
pairs were to be inconsistently updated, this patch this cleans
up how we modify these value pairs to ensure we are always
consistent.
As a side-effect this is also more efficient as we only
caulculate the duplicate values when they are changed,
rather then every update_wall_time call.
This also provides WARN_ONs to detect if future changes break
the invariants.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343414893-45779-5-git-send-email-john.stultz@linaro.org
[ Cleaned up minor style issues. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ingo noted that ACTHZ is a confusing name, and requested it
be renamed, so this patch renames ACTHZ to SHIFTED_HZ to
better describe it.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343414893-45779-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
commit 1e75fa8b (time: Condense timekeeper.xtime into xtime_sec)
introduced helper functions which apply a timespec to the core
internal timekeeper data. The internal storage type is u64. The
timespec tv_nsec value must be shifted before set or added to the
internal value. tv_nsec is a long, which is 32bit on a 32bit system,
so without casting tv_nsec to u64 we lose the bits which are shifted
over the 32bit boundary.
Add the proper typecasts.
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343074957-16541-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull timer core changes from Ingo Molnar:
"Continued cleanups of the core time and NTP code, plus more nohz work
preparing for tick-less userspace execution."
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Rework timekeeping functions to take timekeeper ptr as argument
time: Move xtime_nsec adjustment underflow handling timekeeping_adjust
time: Move arch_gettimeoffset() usage into timekeeping_get_ns()
time: Refactor accumulation of nsecs to secs
time: Condense timekeeper.xtime into xtime_sec
time: Explicitly use u32 instead of int for shift values
time: Whitespace cleanups per Ingo%27s requests
nohz: Move next idle expiry time record into idle logic area
nohz: Move ts->idle_calls incrementation into strict idle logic
nohz: Rename ts->idle_tick to ts->last_tick
nohz: Make nohz API agnostic against idle ticks cputime accounting
nohz: Separate idle sleeping time accounting from nohz logic
timers: Improve get_next_timer_interrupt()
timers: Add accounting of non deferrable timers
timers: Consolidate base->next_timer update
timers: Create detach_if_pending() and use it
Pull RCU changes from Ingo Molnar:
"Quoting from Paul, the major features of this series are:
1. Preventing latency spikes of more than 200 microseconds for
kernels built with NR_CPUS=4096, which is reportedly becoming the
default for some distros. This is a first step, as it does not
help with systems that actually -have- 4096 CPUs (work on this case
is in progress, but is not yet ready for mainline).
This category also includes improving concurrency of rcu_barrier(),
placed here due to conflicts. Posted to LKML at:
https://lkml.org/lkml/2012/6/22/381
Note that patches 18-22 of that series have been defered to 3.7, as
they have not yet proven themselves to be mainline-ready (and yes,
these are the ones intended to get rid of RCU's latency spikes for
systems that actually have 4096 CPUs).
2. Updates to documentation and rcutorture fixes, the latter category
including improvements to rcu_barrier() testing. Posted to LKML at
http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/04094.html.
3. Miscellaneous fixes posted to LKML at:
https://lkml.org/lkml/2012/6/22/500
with the exception of the last commit, which was posted here:
http://www.gossamer-threads.com/lists/linux/kernel/1561830
4. RCU_FAST_NO_HZ fixes and improvements. Posted to LKML at:
http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/00006.htmlhttp://www.gossamer-threads.com/lists/linux/kernel/1561833
The first four patches of the first series went into 3.5 to fix a
regression.
5. Code-style fixes. These were posted to LKML at
http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01180.htmlhttp://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01181.html"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
rcu: Fix broken strings in RCU's source code.
rcu: Fix code-style issues involving "else"
rcu: Introduce check for callback list/count mismatch
rcu: Make RCU_FAST_NO_HZ respect nohz= boot parameter
rcu: Fix qlen_lazy breakage
rcu: Round FAST_NO_HZ lazy timeout to nearest second
rcu: The rcu_needs_cpu() function is not a quiescent state
rcu: Dump only the current CPU's buffers for idle-entry/exit warnings
rcu: Add check for CPUs going offline with callbacks queued
rcu: Disable preemption in rcu_blocking_is_gp()
rcu: Prevent uninitialized string in RCU CPU stall info
rcu: Fix rcu_is_cpu_idle() #ifdef in TINY_RCU
rcu: Split RCU core processing out of __call_rcu()
rcu: Prevent __call_rcu() from invoking RCU core on offline CPUs
rcu: Make __call_rcu() handle invocation from idle
rcu: Remove function versions of __kfree_rcu and __is_kfree_rcu_offset
rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations
rcu: Remove return value from rcu_assign_pointer()
key: Remove extraneous parentheses from rcu_assign_keypointer()
rcu: Remove return value from RCU_INIT_POINTER()
...
One more time/ntp fix pulled from Ingo Molnar.
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ntp: Fix STA_INS/DEL clearing bug
The leap second rework unearthed another issue of inconsistent data.
On timekeeping_resume() the timekeeper data is updated, but nothing
calls timekeeping_update(), so now the update code in the timer
interrupt sees stale values.
This has been the case before those changes, but then the timer
interrupt was using stale data as well so this went unnoticed for quite
some time.
Add the missing update call, so all the data is consistent everywhere.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Reported-and-tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Reported-and-tested-by: Martin Steigerwald <Martin@lichtvoll.de>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As part of cleaning up the timekeeping code, this patch converts
a number of internal functions to takei a timekeeper ptr as an
argument, so that the internal functions don't access the global
timekeeper structure directly. This allows for further optimizations
to reduce lock hold time later.
This patch has been updated to include more consistent usage of the
timekeeper value, by making sure it is always passed as a argument
to non top-level functions.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-9-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When we make adjustments speeding up the clock, its possible
for xtime_nsec to underflow. We already handle this properly,
but we do so from update_wall_time() instead of the more logical
timekeeping_adjust(), where the possible underflow actually
occurs.
Thus, move the correction logic to the timekeeping_adjust, which
is the function that causes the issue. Making update_wall_time()
more readable.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-8-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since we call arch_gettimeoffset() in all the accessor
functions, move arch_gettimeoffset() calls into
timekeeping_get_ns() and timekeeping_get_ns_raw() to simplify
the code.
This also makes the code easier to maintain as we don't have to
worry about forgetting the arch_gettimeoffset() as has happened
in the past.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-7-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We do the exact same logic moving nsecs to secs in the
timekeeper in multiple places, so condense this into a
single function.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-6-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The timekeeper struct has a xtime_nsec, which keeps the
sub-nanosecond remainder. This ends up being somewhat
duplicative of the timekeeper.xtime.tv_nsec value, and we
have to do extra work to keep them apart, copying the full
nsec portion out and back in over and over.
This patch simplifies some of the logic by taking the timekeeper
xtime value and splitting it into timekeeper.xtime_sec and
reuses the timekeeper.xtime_nsec for the sub-second portion
(stored in higher res shifted nanoseconds).
This simplifies some of the accumulation logic. And will
allow for more accurate timekeeping once the vsyscall code
is updated to use the shifted nanosecond remainder.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ingo noted that using a u32 instead of int for shift values
would be better to make sure the compiler doesn't unnecessarily
use complex signed arithmetic.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ingo noted a number of places where there is inconsistent
use of whitespace. This patch tries to address the main
culprits.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1342156917-25092-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reason: Update to upstream changes to avoid further conflicts.
Fixup a trivial merge conflict in kernel/time/tick-sched.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In commit 6b43ae8a61, I
introduced a bug that kept the STA_INS or STA_DEL bit
from being cleared from time_status via adjtimex()
without forcing STA_PLL first.
Usually once the STA_INS is set, it isn't cleared
until the leap second is applied, so its unlikely this
affected anyone. However during testing I noticed it
took some effort to cancel a leap second once STA_INS
was set.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
CC: stable@vger.kernel.org # 3.4
Link: http://lkml.kernel.org/r/1342156917-25092-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull RCU, perf, and scheduler fixes from Ingo Molnar.
The RCU fix is a revert for an optimization that could cause deadlocks.
One of the scheduler commits (164c33c6ad "sched: Fix fork() error path
to not crash") is correct but not complete (some architectures like Tile
are not covered yet) - the resulting additional fixes are still WIP and
Ingo did not want to delay these pending fixes. See this thread on
lkml:
[PATCH] fork: fix error handling in dup_task()
The perf fixes are just trivial oneliners.
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf kvm: Fix segfault with report and mixed guestmount use
perf kvm: Fix regression with guest machine creation
perf script: Fix format regression due to libtraceevent merge
ring-buffer: Fix accounting of entries when removing pages
ring-buffer: Fix crash due to uninitialized new_pages list head
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS/sched: Update scheduler file pattern
sched/nohz: Rewrite and fix load-avg computation -- again
sched: Fix fork() error path to not crash
To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We need to update the hrtimer clock offsets from the hrtimer interrupt
context. To avoid conversions from timespec to ktime_t maintain a
ktime_t based representation of those offsets in the timekeeper. This
puts the conversion overhead into the code which updates the
underlying offsets and provides fast accessible values in the hrtimer
interrupt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-4-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The timekeeping code misses an update of the hrtimer subsystem after a
leap second happened. Due to that timers based on CLOCK_REALTIME are
either expiring a second early or late depending on whether a leap
second has been inserted or deleted until an operation is initiated
which causes that update. Unless the update happens by some other
means this discrepancy between the timekeeping and the hrtimer data
stays forever and timers are expired either early or late.
The reported immediate workaround - $ data -s "`date`" - is causing a
call to clock_was_set() which updates the hrtimer data structures.
See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix
Add the missing clock_was_set() call to update_wall_time() in case of
a leap second event. The actual update is deferred to softirq context
as the necessary smp function call cannot be invoked from hard
interrupt context.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
