Commit Graph

79 Commits

Author SHA1 Message Date
Linus Torvalds
f9ee7f60d6 Merge branches 'core-fixes-for-linus', 'x86-fixes-for-linus', 'timers-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: avoid pointless blocked-task warnings
  rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
  rtmutex: Fix comment about why new_owner can be NULL in wake_futex_pi()

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, olpc: Add missing Kconfig dependencies
  x86, mrst: Set correct APB timer IRQ affinity for secondary cpu
  x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
  x86, ia64, acpi: Clean up x86-ism in drivers/acpi/numa.c

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timekeeping: Make local variables static
  time: Rename misnamed minsec argument of clocks_calc_mult_shift()

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: Remove syscall_exit_fields
  tracing: Only process module tracepoints once
  perf record: Add "nodelay" mode, disabled by default
  perf sched: Fix list of events, dropping unsupported ':r' modifier
  Revert "perf tools: Emit clearer message for sys_perf_event_open ENOENT return"
  perf top: Fix annotate segv
  perf evsel: Fix order of event list deletion
2011-01-15 12:45:00 -08:00
John Stultz
62627bec8a x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
Konrad Wilk reported that the new delayed calibration crashes with a
divide by zero on Xen. The reason is that Xen sets the pmtimer
address, but reading from it returns 0xffffff. That results in the
ref_start and ref_stop value being the same, so the delta is zero
which causes the divide by zero later in the calculation.

The conditional (!hpet && !ref_start && !ref_stop) which sanity checks
the calibration reference values doesn't really make sense. If the
refs are null, but hpet is on, we still want to break out.

The div by zero would be possible to trigger by chance if both reads
from the hardware provided the exact same value (due to hardware
wrapping).

So checking if both the ref values are the same should handle if we
don't have hardware (both null) or if they are the same value (either by
invalid hardware, or by chance), avoiding the div by zero issue.

[ tglx: Applied the same fix to native_calibrate_tsc() where this
  	check was copied from ]

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1295024788-15619-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-14 18:28:01 +01:00
Linus Torvalds
16ee8db6a9 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Fix Moorestown VRTC fixmap placement
  x86/gpio: Implement x86 gpio_to_irq convert function
  x86, UV: Fix APICID shift for Westmere processors
  x86: Use PCI method for enabling AMD extended config space before MSR method
  x86: tsc: Prevent delayed init if initial tsc calibration failed
  x86, lapic-timer: Increase the max_delta to 31 bits
  x86: Fix sparse non-ANSI function warnings in smpboot.c
  x86, numa: Fix CONFIG_DEBUG_PER_CPU_MAPS without NUMA emulation
  x86, AMD, PCI: Add AMD northbridge PCI device id for CPU families 12h and 14h
  x86, numa: Fix cpu to node mapping for sparse node ids
  x86, numa: Fake node-to-cpumask for NUMA emulation
  x86, numa: Fake apicid and pxm mappings for NUMA emulation
  x86, numa: Avoid compiling NUMA emulation functions without CONFIG_NUMA_EMU
  x86, numa: Reduce minimum fake node size to 32M

Fix up trivial conflict in arch/x86/kernel/apic/x2apic_uv_x.c
2011-01-11 11:11:46 -08:00
Thomas Gleixner
29fe359ca2 x86: tsc: Prevent delayed init if initial tsc calibration failed
commit a8760ec (x86: Check tsc available/disabled in the delayed init
function) missed to prevent the setup of the delayed init function in
case the initial tsc calibration failed. This results in the same
divide by zero bug as we have seen without the tsc disabled check.

Skip the delayed work setup when tsc_khz (the initial calibration
value) is 0.

Bisected-and-tested-by: Kirill A. Shutemov <kas@openvz.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-11 11:48:39 +01:00
Linus Torvalds
72eb6a7914 Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
  gameport: use this_cpu_read instead of lookup
  x86: udelay: Use this_cpu_read to avoid address calculation
  x86: Use this_cpu_inc_return for nmi counter
  x86: Replace uses of current_cpu_data with this_cpu ops
  x86: Use this_cpu_ops to optimize code
  vmstat: User per cpu atomics to avoid interrupt disable / enable
  irq_work: Use per cpu atomics instead of regular atomics
  cpuops: Use cmpxchg for xchg to avoid lock semantics
  x86: this_cpu_cmpxchg and this_cpu_xchg operations
  percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
  percpu,x86: relocate this_cpu_add_return() and friends
  connector: Use this_cpu operations
  xen: Use this_cpu_inc_return
  taskstats: Use this_cpu_ops
  random: Use this_cpu_inc_return
  fs: Use this_cpu_inc_return in buffer.c
  highmem: Use this_cpu_xx_return() operations
  vmstat: Use this_cpu_inc_return for vm statistics
  x86: Support for this_cpu_add, sub, dec, inc_return
  percpu: Generic support for this_cpu_add, sub, dec, inc_return
  ...

Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
2011-01-07 17:02:58 -08:00
Tejun Heo
0a3aee0da4 x86: Use this_cpu_ops to optimize code
Go through x86 code and replace __get_cpu_var and get_cpu_var
instances that refer to a scalar and are not used for address
determinations.

Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-12-30 12:20:28 +01:00
Thomas Gleixner
a8760eca6c x86: Check tsc available/disabled in the delayed init function
The delayed TSC init function does not check whether the system has no
TSC or TSC is disabled at the kernel command line, which results in a
crash in the work queue based extended calibration due to division by
zero because the basic calibration never happened.

Add the missing checks and do not touch TSC when not available or
disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
2010-12-13 11:35:05 +01:00
John Stultz
08ec0c58fb x86: Improve TSC calibration using a delayed workqueue
Boot to boot the TSC calibration may vary by quite a large amount.

While normal variance of 50-100ppm can easily be seen, the quick
calibration code only requires 500ppm accuracy, which is the limit
of what NTP can correct for.

This can cause problems for systems being used as NTP servers, as
every time they reboot it can take hours for them to calculate the
new drift error caused by the calibration.

The classic trade-off here is calibration accuracy vs slow boot times,
as during the calibration nothing else can run.

This patch uses a delayed workqueue  to calibrate the TSC over the
period of a second. This allows very accurate calibration (in my
tests only varying by 1khz or 0.4ppm boot to boot). Additionally this
refined calibration step does not block the boot process, and only
delays the TSC clocksoure registration by a few seconds in early boot.
If the refined calibration strays 1% from the early boot calibration
value, the system will fall back to already calculated early boot
calibration.

Credit to Andi Kleen who suggested using a timer quite awhile back,
but I dismissed it thinking the timer calibration would be done after
the clocksource was registered (which would break things). Forgive
me for my short-sightedness.

This patch has worked very well in my testing, but TSC hardware is
quite varied so it would probably be good to get some extended
testing, possibly pushing inclusion out to 2.6.39.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1289003985-29060-1-git-send-email-johnstul@us.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@elte.hu>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Clark Williams <williams@redhat.com>
CC: Andi Kleen <andi@firstfloor.org>
2010-12-02 16:48:37 -08:00
John Stultz
b0f969009f Merge remote branch 'tip/x86/tsc' into fortglx/2.6.38/tip/x86/tsc
Conflicts:
	Documentation/kernel-parameters.txt
2010-12-02 16:47:52 -08:00
Linus Torvalds
2f0384e5fc Merge branch 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, amd_nb: Enable GART support for AMD family 0x15 CPUs
  x86, amd: Use compute unit information to determine thread siblings
  x86, amd: Extract compute unit information for AMD CPUs
  x86, amd: Add support for CPUID topology extension of AMD CPUs
  x86, nmi: Support NMI watchdog on newer AMD CPU families
  x86, mtrr: Assume SYS_CFG[Tom2ForceMemTypeWB] exists on all future AMD CPUs
  x86, k8: Rename k8.[ch] to amd_nb.[ch] and CONFIG_K8_NB to CONFIG_AMD_NB
  x86, k8-gart: Decouple handling of garts and northbridges
  x86, cacheinfo: Fix dependency of AMD L3 CID
  x86, kvm: add new AMD SVM feature bits
  x86, cpu: Fix allowed CPUID bits for KVM guests
  x86, cpu: Update AMD CPUID feature bits
  x86, cpu: Fix renamed, not-yet-shipping AMD CPUID feature bit
  x86, AMD: Remove needless CPU family check (for L3 cache info)
  x86, tsc: Remove CPU frequency calibration on AMD
2010-10-21 13:01:08 -07:00
Venkatesh Pallipadi
e82b8e4ea4 x86: Add IRQ_TIME_ACCOUNTING
This patch adds IRQ_TIME_ACCOUNTING option on x86 and runtime enables it
when TSC is enabled.

This change just enables fine grained irq time accounting, isn't used yet.
Following patches use it for different purposes.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-6-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-18 20:52:25 +02:00
H. Peter Anvin
86ffb08519 Merge remote branch 'origin/x86/cpu' into x86/amd-nb 2010-10-01 16:18:11 -07:00
Peter Zijlstra
5ee5e97ee9 x86, tsc: Fix a preemption leak in restore_sched_clock_state()
A real life genuine preemption leak..

Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-09-10 18:17:45 -07:00
Borislav Petkov
acf01734b1 x86, tsc: Remove CPU frequency calibration on AMD
6b37f5a20c introduced the CPU frequency
calibration code for AMD CPUs whose TSCs didn't increment with the
core's P0 frequency. From F10h, revB onward, however, the TSC increment
rate is denoted by MSRC001_0015[24] and when this bit is set (which
should be done by the BIOS) the TSC increments with the P0 frequency
so the calibration is not needed and booting can be a couple of mcecs
faster on those machines.

Besides, there should be virtually no machines out there which don't
have this bit set, therefore this calibration can be safely removed. It
is a shaky hack anyway since it assumes implicitly that the core is in
P0 when BIOS hands off to the OS, which might not always be the case.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100825162823.GE26438@aftab>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-08-25 13:32:52 -07:00
Suresh Siddha
cd7240c0b9 x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states
TSC's get reset after suspend/resume (even on cpu's with invariant TSC
which runs at a constant rate across ACPI P-, C- and T-states). And in
some systems BIOS seem to reinit TSC to arbitrary large value (still
sync'd across cpu's) during resume.

This leads to a scenario of scheduler rq->clock (sched_clock_cpu()) less
than rq->age_stamp (introduced in 2.6.32). This leads to a big value
returned by scale_rt_power() and the resulting big group power set by the
update_group_power() is causing improper load balancing between busy and
idle cpu's after suspend/resume.

This resulted in multi-threaded workloads (like kernel-compilation) go
slower after suspend/resume cycle on core i5 laptops.

Fix this by recomputing cyc2ns_offset's during resume, so that
sched_clock() continues from the point where it was left off during
suspend.

Reported-by: Florian Pritz <flo@xssn.at>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org> # [v2.6.32+]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-08-20 14:59:02 +02:00
John Stultz
f12a15be63 x86: Convert common clocksources to use clocksource_register_hz/khz
This converts the most common of the x86 clocksources over to use
clocksource_register_hz/khz.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-11-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-07-27 12:40:55 +02:00
Jiri Kosina
318ae2edc3 Merge branch 'for-next' into for-linus
Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c
2010-03-08 16:55:37 +01:00
Linus Torvalds
e56425b135 Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  posix-timers.c: Don't export local functions
  clocksource: start CMT at clocksource resume
  clocksource: add suspend callback
  clocksource: add argument to resume callback
  ntp: Cleanup xtime references in ntp.c
  ntp: Make time_esterror and time_maxerror static
2010-03-01 08:48:25 -08:00
Daniel Mack
3ad2f3fbb9 tree-wide: Assorted spelling fixes
In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-02-09 11:13:56 +01:00
Magnus Damm
17622339af clocksource: add argument to resume callback
Pass the clocksource as an argument to the clocksource resume callback. 
Needed so we can point out which CMT channel the sh_cmt.c driver shall
resume.

Signed-off-by: Magnus Damm <damm@opensource.se>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-02-05 14:54:10 +01:00
Thadeu Lima de Souza Cascardo
00097c4fdf x86, trivial: Fix grammo in tsc comment about Geode TSC reliability
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: marcelo@kvack.org
Cc: dilinger@collabora.co.uk
Cc: trivial@kernel.org
LKML-Reference: <1263764685-9871-1-git-send-email-cascardo@holoscopio.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-18 09:01:39 +01:00
Pallipadi, Venkatesh
6c56ccecf0 x86: Reenable TSC sync check at boot, even with NONSTOP_TSC
Commit 83ce4009 did the following change
If the TSC is constant and non-stop, also set it reliable.

But, there seems to be few systems that will end up with TSC warp across
sockets, depending on how the cpus come out of reset. Skipping TSC sync
test on such systems may result in time inconsistency later.

So, reenable TSC sync test even on constant and non-stop TSC systems.
Set, sched_clock_stable to 1 by default and reset it in
mark_tsc_unstable, if TSC sync fails.

This change still gives perf benefit mentioned in 83ce4009 for systems
where TSC is reliable.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-12-17 14:44:35 -08:00
Ingo Molnar
bfefb7a0c6 Merge branch 'linus' into x86/urgent
Merge reason: Bring in changes that the next patch will depend on.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-20 20:25:03 +02:00
Felipe Contreras
878f4f533e x86: Trivial whitespace cleanups
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alok N Kataria <akataria@vmware.com>
Cc: "Tan Wei Chong" <wei.chong.tan@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Bob Moore <robert.moore@intel.com>
LKML-Reference: <1253137123-18047-2-git-send-email-felipe.contreras@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-20 20:18:57 +02:00
Linus Torvalds
78f28b7c55 Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (38 commits)
  x86: Move get/set_wallclock to x86_platform_ops
  x86: platform: Fix section annotations
  x86: apic namespace cleanup
  x86: Distangle ioapic and i8259
  x86: Add Moorestown early detection
  x86: Add hardware_subarch ID for Moorestown
  x86: Add early platform detection
  x86: Move tsc_init to late_time_init
  x86: Move tsc_calibration to x86_init_ops
  x86: Replace the now identical time_32/64.c by time.c
  x86: time_32/64.c unify profile_pc
  x86: Move calibrate_cpu to tsc.c
  x86: Make timer setup and global variables the same in time_32/64.c
  x86: Remove mca bus ifdef from timer interrupt
  x86: Simplify timer_ack magic in time_32.c
  x86: Prepare unification of time_32/64.c
  x86: Remove do_timer hook
  x86: Add timer_init to x86_init_ops
  x86: Move percpu clockevents setup to x86_init_ops
  x86: Move xen_post_allocator_init into xen_pagetable_setup_done
  ...

Fix up conflicts in arch/x86/include/asm/io_apic.h
2009-09-18 14:05:47 -07:00
Thomas Gleixner
2d826404f0 x86: Move tsc_calibration to x86_init_ops
TSC calibration is modified by the vmware hypervisor and paravirt by
separate means. Moorestown wants to add its own calibration routine as
well. So make calibrate_tsc a proper x86_init_ops function and
override it by paravirt or by the early setup of the vmware
hypervisor.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-31 09:35:47 +02:00
Thomas Gleixner
08047c4f17 x86: Move calibrate_cpu to tsc.c
Move the code where it's only user is. Also we need to look whether
this hardwired hackery might interfere with perfcounters.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-31 09:35:46 +02:00
Thomas Gleixner
845b3944bb x86: Add timer_init to x86_init_ops
The timer init code is convoluted with several quirks and the paravirt
timer chooser. Figuring out which code path is actually taken is not
for the faint hearted.

Move the numaq TSC quirk to tsc_pre_init x86_init_ops function and
replace the paravirt time chooser and the remaining x86 quirk with a
simple x86_init_ops function.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-31 09:35:46 +02:00
john stultz
d3b8f889a2 x86: Make tsc=reliable override boot time stability checks
This patch makes the tsc=reliable option disable the boot time
stability checks. Currently the option only disables the runtime
watchdog checks. This change allows folks who want to override the
boot time TSC stability checks and use the TSC when the system would
otherwise disqualify it.

There still are some situations that the TSC will be disqualified,
such as cpufreq scaling. But these are situations where the box will
hang if allowed.

Patch also includes a fix for an issue found by Thomas Gleixner, where
the TSC disqualification message wouldn't be printed after a call to
unsynchronized_tsc().

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: akataria@vmware.com
Cc: Stephen Hemminger <shemminger@vyatta.com>
LKML-Reference: <1250552447.7212.92.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-28 21:13:05 +02:00
Thomas Gleixner
7285dd7fd3 clocksource: Resolve cpu hotplug dead lock with TSC unstable
Martin Schwidefsky analyzed it:
To register a clocksource the clocksource_mutex is acquired and if
necessary timekeeping_notify is called to install the clocksource as
the timekeeper clock. timekeeping_notify uses stop_machine which needs
to take cpu_add_remove_lock mutex.
Starting a new cpu is done with the cpu_add_remove_lock mutex held.
native_cpu_up checks the tsc of the new cpu and if the tsc is no good
clocksource_change_rating is called. Which needs the clocksource_mutex
and the deadlock is complete.

The solution is to replace the TSC via the clocksource watchdog
mechanism. Mark the TSC as unstable and schedule the watchdog work so
it gets removed in the watchdog thread context.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>
2009-08-28 20:25:24 +02:00
Martin Schwidefsky
1be3967948 timekeeping: Move reset of cycle_last for tsc clocksource to tsc
change_clocksource resets the cycle_last value to zero then sets it to
a value read from the clocksource. The reset to zero is required only
for the TSC clocksource to make the read_tsc function work after a
resume. The reason is that the TSC read function uses cycle_last to
detect backwards going TSCs. In the resume case cycle_last contains
the TSC value from the last update before the suspend. On resume the
TSC starts counting from 0 again and would trip over the cycle_last
comparison.

This is subtle and surprising. Move the reset to a resume function in
the tsc code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134808.142191175@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-15 10:55:45 +02:00
Linus Torvalds
b6e61eef4f x86: Fix serialization in pit_expect_msb()
Wei Chong Tan reported a fast-PIT-calibration corner-case:

| pit_expect_msb() is vulnerable to SMI disturbance corner case
| in some platforms which causes /proc/cpuinfo to show wrong
| CPU MHz value when quick_pit_calibrate() jumps to success
| section.

I think that the real issue isn't even an SMI - but the fact
that in the very last iteration of the loop, there's no
serializing instruction _after_ the last 'rdtsc'. So even in
the absense of SMI's, we do have a situation where the cycle
counter was read without proper serialization.

The last check should be done outside the outer loop, since
_inside_ the outer loop, we'll be testing that the PIT has
the right MSB value has the right value in the next iteration.

So only the _last_ iteration is special, because that's the one
that will not check the PIT MSB value any more, and because the
final 'get_cycles()' isn't serialized.

In other words:

 - I'd like to move the PIT MSB check to after the last
   iteration, rather than in every iteration

 - I think we should comment on the fact that it's also a
   serializing instruction and so 'fences in' the TSC read.

Here's a suggested replacement.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: "Tan, Wei Chong" <wei.chong.tan@intel.com>
Tested-by: "Tan, Wei Chong" <wei.chong.tan@intel.com>
LKML-Reference: <B28277FD4E0F9247A3D55704C440A140D5D683F3@pgsmsx504.gar.corp.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-08-10 19:56:57 +02:00
Linus Torvalds
1eb51c33b2 Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Fix out of scope variable access in sched_slice()
  sched: Hide runqueues from direct refer at source code level
  sched: Remove unneeded __ref tag
  sched, x86: Fix cpufreq + sched_clock() TSC scaling
2009-06-20 10:57:40 -07:00
Linus Torvalds
c30938d59e Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
  [CPUFREQ] cpumask: new cpumask operators for arch/x86/kernel/cpu/cpufreq/powernow-k8.c
  [CPUFREQ] cpumask: avoid playing with cpus_allowed in powernow-k8.c
  [CPUFREQ] cpumask: avoid cpumask games in arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c
  [CPUFREQ] cpumask: avoid playing with cpus_allowed in speedstep-ich.c
  [CPUFREQ] powernow-k8: get drv data for correct CPU
  [CPUFREQ] powernow-k8: read P-state from HW
  [CPUFREQ] reduce scope of ACPI_PSS_BIOS_BUG_MSG[]
  [CPUFREQ] Clean up convoluted code in arch/x86/kernel/tsc.c:time_cpufreq_notifier()
  [CPUFREQ] minor correction to cpu-freq documentation
  [CPUFREQ] powernow-k8.c: mess cleanup
  [CPUFREQ] Only set sampling_rate_max deprecated, sampling_rate_min is useful
  [CPUFREQ] powernow-k8: Set transition latency to 1 if ACPI tables export 0
  [CPUFREQ] ondemand: Uncouple minimal sampling rate from HZ in NO_HZ case
2009-06-17 09:51:50 -07:00
Peter Zijlstra
84599f8a59 sched, x86: Fix cpufreq + sched_clock() TSC scaling
For freqency dependent TSCs we only scale the cycles, we do not account
for the discrepancy in absolute value.

Our current formula is: time = cycles * mult

(where mult is a function of the cpu-speed on variable tsc machines)

Suppose our current cycle count is 10, and we have a multiplier of 5,
then our time value would end up being 50.

Now cpufreq comes along and changes the multiplier to say 3 or 7,
which would result in our time being resp. 30 or 70.

That means that we can observe random jumps in the time value due to
frequency changes in both fwd and bwd direction.

So what this patch does is change the formula to:

  time = cycles * frequency + offset

And we calculate offset so that time_before == time_after, thereby
ridding us of these jumps in time.

[ Impact: fix/reduce sched_clock() jumps across frequency changing events ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Chucked-on-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2009-06-17 16:03:54 +02:00
Arnd Bergmann
08604bd993 time: move PIT_TICK_RATE to linux/timex.h
PIT_TICK_RATE is currently defined in four architectures, but in three
different places.  While linux/timex.h is not the perfect place for it, it
is still a reasonable replacement for those drivers that traditionally use
asm/timex.h to get CLOCK_TICK_RATE and expect it to be the PIT frequency.

Note that for Alpha, the actual value changed from 1193182UL to 1193180UL.
 This is unlikely to make a difference, and probably can only improve
accuracy.  There was a discussion on the correct value of CLOCK_TICK_RATE
a few years ago, after which every existing instance was getting changed
to 1193182.  According to the specification, it should be
1193181.818181...

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Len Brown <lenb@kernel.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16 19:47:27 -07:00
Dave Jones
931db6a32d [CPUFREQ] Clean up convoluted code in arch/x86/kernel/tsc.c:time_cpufreq_notifier()
Christoph Hellwig noticed the following potential uninitialised use:

 > arch/x86/kernel/tsc.c: In function 'time_cpufreq_notifier':
 > arch/x86/kernel/tsc.c:634: warning: 'dummy' may be used uninitialized in this function
 >
 > where we do have CONFIG_SMP set, freq->flags & CPUFREQ_CONST_LOOPS is
 > true and ref_freq is false.

It seems plausable, though the circumstances for hitting it are really low.
Nearly all SMP capable cpufreq drivers set CPUFREQ_CONST_LOOPS.
powernow-k8 is really the only exception. The older CPUs were typically
only ever UP. (powernow-k7 never supported SMP for eg)

It's worth fixing regardless, as it cleans up the code.

Fix possible uninitialized use of dummy, by just removing it,
and making the setting of lpj more obvious.

Signed-off-by: Dave Jones <davej@redhat.com>
2009-06-15 11:49:42 -04:00
Linus Torvalds
595dc54a1d Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: move rdtsc_barrier() into the TSC vread method
2009-06-10 16:15:59 -07:00
Linus Torvalds
7dc3ca39cb Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, nmi: Use predefined numbers instead of hardcoded one
  x86: asm/processor.h: remove double declaration
  x86, mtrr: replace MTRRdefType_MSR with msr-index's MSR_MTRRdefType
  x86, mtrr: replace MTRRfix4K_C0000_MSR with msr-index's MSR_MTRRfix4K_C0000
  x86, mtrr: remove mtrr MSRs double declaration
  x86, mtrr: replace MTRRfix16K_80000_MSR with msr-index's MSR_MTRRfix16K_80000
  x86, mtrr: replace MTRRfix64K_00000_MSR with msr-index's MSR_MTRRfix64K_00000
  x86, mtrr: replace MTRRcap_MSR with msr-index's MSR_MTRRcap
  x86: mce: remove duplicated #include
  x86: msr-index.h remove duplicate MSR C001_0015 declaration
  x86: clean up arch/x86/kernel/tsc_sync.c a bit
  x86: use symbolic name for VM86_SIGNAL when used as vm86 default return
  x86: added 'ifndef _ASM_X86_IOMAP_H' to iomap.h
  x86: avoid multiple declaration of kstack_depth_to_print
  x86: vdso/vma.c declare vdso_enabled and arch_setup_additional_pages before they get used
  x86: clean up declarations and variables
  x86: apic/x2apic_cluster.c x86_cpu_to_logical_apicid should be static
  x86 early quirks: eliminate unused function
2009-06-10 15:49:36 -07:00
Petr Tesarik
7d96fd41ca x86: move rdtsc_barrier() into the TSC vread method
The *fence instructions were moved to vsyscall_64.c by commit
cb9e35dce9.  But this breaks the
vDSO, because vread methods are also called from there.

Besides, the synchronization might be unnecessary for other
time sources than TSC.

[ Impact: fix potential time warp in VDSO ]

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
LKML-Reference: <9d0ea9ea0f866bdc1f4d76831221ae117f11ea67.1243241859.git.ptesarik@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
2009-05-28 14:15:54 +02:00
Magnus Damm
8e19608e8b clocksource: pass clocksource to read() callback
Pass clocksource pointer to the read() callback for clocksources.  This
allows us to share the callback between multiple instances.

[hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-21 13:41:47 -07:00
Jaswinder Singh Rajput
2c1b284e4f x86: clean up declarations and variables
Impact: cleanup, no code changed

 - syscalls.h       update declarations due to unifications
 - irq.c            declare smp_generic_interrupt() before it gets used
 - process.c        declare sys_fork() and sys_vfork() before they get used
 - tsc.c            rename tsc_khz shadowed variable
 - apic/probe_32.c  declare apic_default before it gets used
 - apic/nmi.c       prev_nmi_count should be unsigned
 - apic/io_apic.c   declare smp_irq_move_cleanup_interrupt() before it gets used
 - mm/init.c        declare direct_gbpages and free_initrd_mem before they get used

Signed-off-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-12 15:20:16 +02:00
Ingo Molnar
6e15cf0486 Merge branch 'core/percpu' into percpu-cpumask-x86-for-linus-2
Conflicts:
	arch/parisc/kernel/irq.c
	arch/x86/include/asm/fixmap_64.h
	arch/x86/include/asm/setup.h
	kernel/irq/handle.c

Semantic merge:
        arch/x86/include/asm/fixmap.h

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-27 17:28:43 +01:00
Linus Torvalds
831576fe40 Merge branch 'sched-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (46 commits)
  sched: Add comments to find_busiest_group() function
  sched: Refactor the power savings balance code
  sched: Optimize the !power_savings_balance during fbg()
  sched: Create a helper function to calculate imbalance
  sched: Create helper to calculate small_imbalance in fbg()
  sched: Create a helper function to calculate sched_domain stats for fbg()
  sched: Define structure to store the sched_domain statistics for fbg()
  sched: Create a helper function to calculate sched_group stats for fbg()
  sched: Define structure to store the sched_group statistics for fbg()
  sched: Fix indentations in find_busiest_group() using gotos
  sched: Simple helper functions for find_busiest_group()
  sched: remove unused fields from struct rq
  sched: jiffies not printed per CPU
  sched: small optimisation of can_migrate_task()
  sched: fix typos in documentation
  sched: add avg_overlap decay
  x86, sched_clock(): mark variables read-mostly
  sched: optimize ttwu vs group scheduling
  sched: TIF_NEED_RESCHED -> need_reshed() cleanup
  sched: don't rebalance if attached on NULL domain
  ...
2009-03-26 16:05:01 -07:00
Linus Torvalds
ada19a31a9 Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq: (35 commits)
  [CPUFREQ] Prevent p4-clockmod from auto-binding to the ondemand governor.
  [CPUFREQ] Make cpufreq-nforce2 less obnoxious
  [CPUFREQ] p4-clockmod reports wrong frequency.
  [CPUFREQ] powernow-k8: Use a common exit path.
  [CPUFREQ] Change link order of x86 cpufreq modules
  [CPUFREQ] conservative: remove 10x from def_sampling_rate
  [CPUFREQ] conservative: fixup governor to function more like ondemand logic
  [CPUFREQ] conservative: fix dbs_cpufreq_notifier so freq is not locked
  [CPUFREQ] conservative: amend author's email address
  [CPUFREQ] Use swap() in longhaul.c
  [CPUFREQ] checkpatch cleanups for acpi-cpufreq
  [CPUFREQ] powernow-k8: Only print error message once, not per core.
  [CPUFREQ] ondemand/conservative: sanitize sampling_rate restrictions
  [CPUFREQ] ondemand/conservative: deprecate sampling_rate{min,max}
  [CPUFREQ] powernow-k8: Always compile powernow-k8 driver with ACPI support
  [CPUFREQ] Introduce /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_transition_latency
  [CPUFREQ] checkpatch cleanups for powernow-k8
  [CPUFREQ] checkpatch cleanups for ondemand governor.
  [CPUFREQ] checkpatch cleanups for powernow-k7
  [CPUFREQ] checkpatch cleanups for speedstep related drivers.
  ...
2009-03-26 11:04:08 -07:00
Ingo Molnar
37ba317c9e Merge branches 'sched/cleanups' and 'linus' into sched/core 2009-03-18 09:57:02 +01:00
Linus Torvalds
9e8912e04e Fast TSC calibration: calculate proper frequency error bounds
In order for ntpd to correctly synchronize the clocks, the frequency of
the system clock must not be off by more than 500 ppm (or, put another
way, 1:2000), or ntpd will end up giving up on trying to synchronize
properly, and ends up reseting the clock in jumps instead.

The fast TSC PIT calibration sometimes failed this test - it was
assuming that the PIT reads always took about one microsecond each (2us
for the two reads to get a 16-bit timer), and that calibrating TSC to
the PIT over 15ms should thus be sufficient to get much closer than
500ppm (max 2us error on both sides giving 4us over 15ms: a 270 ppm
error value).

However, that assumption does not always hold: apparently some hardware
is either very much slower at reading the PIT registers, or there was
other noise causing at least one machine to get 700+ ppm errors.

So instead of using a fixed 15ms timing loop, this changes the fast PIT
calibration to read the TSC delta over the individual PIT timer reads,
and use the result to calculate the error bars on the PIT read timing
properly.  We then successfully calibrate the TSC only if the maximum
error bars fall below 500ppm.

In the process, we also relax the timing to allow up to 25ms for the
calibration, although it can happen much faster depending on hardware.

Reported-and-tested-by: Jesper Krogh <jesper@krogh.cc>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-17 08:13:17 -07:00
Linus Torvalds
a6a80e1d8c Fix potential fast PIT TSC calibration startup glitch
During bootup, when we reprogram the PIT (programmable interval timer)
to start counting down from 0xffff in order to use it for the fast TSC
calibration, we should also make sure to delay a bit afterwards to allow
the PIT hardware to actually start counting with the new value.

That will happens at the next CLK pulse (1.193182 MHz), so the easiest
way to do that is to just wait at least one microsecond after
programming the new PIT counter value.  We do that by just reading the
counter value back once - which will take about 2us on PC hardware.

Reported-and-tested-by: john stultz <johnstul@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-17 07:58:26 -07:00
Ingo Molnar
f24ade3a33 x86, sched_clock(): mark variables read-mostly
Impact: micro-optimization

There's a number of variables in the sched_clock() path that are
in .data/.bss - but not marked __read_mostly. This creates the
danger of accidental false cacheline sharing with some other,
write-often variable.

So mark them __read_mostly.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 19:02:30 +01:00
Matthias-Christian Ott
199785eac8 [CPUFREQ] p4-clockmod reports wrong frequency.
http://bugzilla.kernel.org/show_bug.cgi?id=10968

[ Updated for current tree, and fixed compile failure
  when p4-clockmod was built modular -- davej]

From: Matthias-Christian Ott <ott@mirix.org>
Signed-off-by: Dominik Brodowski <linux@brodo.de>
Signed-off-by: Dave Jones <davej@redhat.com>
2009-02-24 22:47:32 -05:00