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Merge branch 'sched-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

Browse Source 
* 'sched-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (38 commits)
  sched debug: add name to sched_domain sysctl entries
  sched: sync wakeups vs avg_overlap
  sched: remove redundant code in cpu_cgroup_create()
  sched_rt.c: resch needed in rt_rq_enqueue() for the root rt_rq
  cpusets: scan_for_empty_cpusets(), cpuset doesn't seem to be so const
  sched: minor optimizations in wake_affine and select_task_rq_fair
  sched: maintain only task entities in cfs_rq->tasks list
  sched: fixup buddy selection
  sched: more sanity checks on the bandwidth settings
  sched: add some comments to the bandwidth code
  sched: fixlet for group load balance
  sched: rework wakeup preemption
  CFS scheduler: documentation about scheduling policies
  sched: clarify ifdef tangle
  sched: fix list traversal to use _rcu variant
  sched: turn off WAKEUP_OVERLAP
  sched: wakeup preempt when small overlap
  kernel/cpu.c: create a CPU_STARTING cpu_chain notifier
  kernel/cpu.c: Move the CPU_DYING notifiers
  sched: fix __load_balance_iterator() for cfq with only one task
  ...
This commit is contained in:
Linus Torvalds 2008-10-10 12:42:31 -07:00
commit b11ce8a26d
29 changed files with 713 additions and 498 deletions
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4
Documentation/kernel-doc-nano-HOWTO.txt
View File

@ -168,10 +168,10 @@ if ($#ARGV < 0) {
mkdir $ARGV[0],0777;
$state = 0;
while (<STDIN>) {
if (/^\.TH \"[^\"]*\" 4 \"([^\"]*)\"/) {
if (/^\.TH \"[^\"]*\" 9 \"([^\"]*)\"/) {
if ($state == 1) { close OUT }
$state = 1;
$fn = "$ARGV[0]/$1.4";
$fn = "$ARGV[0]/$1.9";
print STDERR "Creating $fn\n";
open OUT, ">$fn" or die "can't open $fn: $!\n";
print OUT $_;

387
Documentation/scheduler/sched-design-CFS.txt
View File

@ -1,151 +1,242 @@
This is the CFS scheduler.
80% of CFS's design can be summed up in a single sentence: CFS basically
models an "ideal, precise multi-tasking CPU" on real hardware.
"Ideal multi-tasking CPU" is a (non-existent :-)) CPU that has 100%
physical power and which can run each task at precise equal speed, in
parallel, each at 1/nr_running speed. For example: if there are 2 tasks
running then it runs each at 50% physical power - totally in parallel.
On real hardware, we can run only a single task at once, so while that
one task runs, the other tasks that are waiting for the CPU are at a
disadvantage - the current task gets an unfair amount of CPU time. In
CFS this fairness imbalance is expressed and tracked via the per-task
p->wait_runtime (nanosec-unit) value. "wait_runtime" is the amount of
time the task should now run on the CPU for it to become completely fair
and balanced.
( small detail: on 'ideal' hardware, the p->wait_runtime value would
always be zero - no task would ever get 'out of balance' from the
'ideal' share of CPU time. )
CFS's task picking logic is based on this p->wait_runtime value and it
is thus very simple: it always tries to run the task with the largest
p->wait_runtime value. In other words, CFS tries to run the task with
the 'gravest need' for more CPU time. So CFS always tries to split up
CPU time between runnable tasks as close to 'ideal multitasking
hardware' as possible.
Most of the rest of CFS's design just falls out of this really simple
concept, with a few add-on embellishments like nice levels,
multiprocessing and various algorithm variants to recognize sleepers.
In practice it works like this: the system runs a task a bit, and when
the task schedules (or a scheduler tick happens) the task's CPU usage is
'accounted for': the (small) time it just spent using the physical CPU
is deducted from p->wait_runtime. [minus the 'fair share' it would have
gotten anyway]. Once p->wait_runtime gets low enough so that another
task becomes the 'leftmost task' of the time-ordered rbtree it maintains
(plus a small amount of 'granularity' distance relative to the leftmost
task so that we do not over-schedule tasks and trash the cache) then the
new leftmost task is picked and the current task is preempted.
The rq->fair_clock value tracks the 'CPU time a runnable task would have
fairly gotten, had it been runnable during that time'. So by using
rq->fair_clock values we can accurately timestamp and measure the
'expected CPU time' a task should have gotten. All runnable tasks are
sorted in the rbtree by the "rq->fair_clock - p->wait_runtime" key, and
CFS picks the 'leftmost' task and sticks to it. As the system progresses
forwards, newly woken tasks are put into the tree more and more to the
right - slowly but surely giving a chance for every task to become the
'leftmost task' and thus get on the CPU within a deterministic amount of
time.
Some implementation details:
- the introduction of Scheduling Classes: an extensible hierarchy of
scheduler modules. These modules encapsulate scheduling policy
details and are handled by the scheduler core without the core
code assuming about them too much.
- sched_fair.c implements the 'CFS desktop scheduler': it is a
replacement for the vanilla scheduler's SCHED_OTHER interactivity
code.
I'd like to give credit to Con Kolivas for the general approach here:
he has proven via RSDL/SD that 'fair scheduling' is possible and that
it results in better desktop scheduling. Kudos Con!
The CFS patch uses a completely different approach and implementation
from RSDL/SD. My goal was to make CFS's interactivity quality exceed
that of RSDL/SD, which is a high standard to meet :-) Testing
feedback is welcome to decide this one way or another. [ and, in any
case, all of SD's logic could be added via a kernel/sched_sd.c module
as well, if Con is interested in such an approach. ]
CFS's design is quite radical: it does not use runqueues, it uses a
time-ordered rbtree to build a 'timeline' of future task execution,
and thus has no 'array switch' artifacts (by which both the vanilla
scheduler and RSDL/SD are affected).
CFS uses nanosecond granularity accounting and does not rely on any
jiffies or other HZ detail. Thus the CFS scheduler has no notion of
'timeslices' and has no heuristics whatsoever. There is only one
central tunable (you have to switch on CONFIG_SCHED_DEBUG):
/proc/sys/kernel/sched_granularity_ns
which can be used to tune the scheduler from 'desktop' (low
latencies) to 'server' (good batching) workloads. It defaults to a
setting suitable for desktop workloads. SCHED_BATCH is handled by the
CFS scheduler module too.
Due to its design, the CFS scheduler is not prone to any of the
'attacks' that exist today against the heuristics of the stock
scheduler: fiftyp.c, thud.c, chew.c, ring-test.c, massive_intr.c all
work fine and do not impact interactivity and produce the expected
behavior.
the CFS scheduler has a much stronger handling of nice levels and
SCHED_BATCH: both types of workloads should be isolated much more
agressively than under the vanilla scheduler.
( another detail: due to nanosec accounting and timeline sorting,
sched_yield() support is very simple under CFS, and in fact under
CFS sched_yield() behaves much better than under any other
scheduler i have tested so far. )
- sched_rt.c implements SCHED_FIFO and SCHED_RR semantics, in a simpler
way than the vanilla scheduler does. It uses 100 runqueues (for all
100 RT priority levels, instead of 140 in the vanilla scheduler)
and it needs no expired array.
- reworked/sanitized SMP load-balancing: the runqueue-walking
assumptions are gone from the load-balancing code now, and
iterators of the scheduling modules are used. The balancing code got
quite a bit simpler as a result.
=============
CFS Scheduler
=============
Group scheduler extension to CFS
================================
1. OVERVIEW
Normally the scheduler operates on individual tasks and strives to provide
fair CPU time to each task. Sometimes, it may be desirable to group tasks
and provide fair CPU time to each such task group. For example, it may
be desirable to first provide fair CPU time to each user on the system
and then to each task belonging to a user.
CFS stands for "Completely Fair Scheduler," and is the new "desktop" process
scheduler implemented by Ingo Molnar and merged in Linux 2.6.23. It is the
replacement for the previous vanilla scheduler's SCHED_OTHER interactivity
code.
CONFIG_FAIR_GROUP_SCHED strives to achieve exactly that. It lets
SCHED_NORMAL/BATCH tasks be be grouped and divides CPU time fairly among such
groups. At present, there are two (mutually exclusive) mechanisms to group
tasks for CPU bandwidth control purpose:
80% of CFS's design can be summed up in a single sentence: CFS basically models
an "ideal, precise multi-tasking CPU" on real hardware.
- Based on user id (CONFIG_FAIR_USER_SCHED)
In this option, tasks are grouped according to their user id.
- Based on "cgroup" pseudo filesystem (CONFIG_FAIR_CGROUP_SCHED)
This options lets the administrator create arbitrary groups
of tasks, using the "cgroup" pseudo filesystem. See
Documentation/cgroups.txt for more information about this
filesystem.
"Ideal multi-tasking CPU" is a (non-existent :-)) CPU that has 100% physical
power and which can run each task at precise equal speed, in parallel, each at
1/nr_running speed. For example: if there are 2 tasks running, then it runs
each at 50% physical power --- i.e., actually in parallel.
On real hardware, we can run only a single task at once, so we have to
introduce the concept of "virtual runtime." The virtual runtime of a task
specifies when its next timeslice would start execution on the ideal
multi-tasking CPU described above. In practice, the virtual runtime of a task
is its actual runtime normalized to the total number of running tasks.
2. FEW IMPLEMENTATION DETAILS
In CFS the virtual runtime is expressed and tracked via the per-task
p->se.vruntime (nanosec-unit) value. This way, it's possible to accurately
timestamp and measure the "expected CPU time" a task should have gotten.
[ small detail: on "ideal" hardware, at any time all tasks would have the same
p->se.vruntime value --- i.e., tasks would execute simultaneously and no task
would ever get "out of balance" from the "ideal" share of CPU time. ]
CFS's task picking logic is based on this p->se.vruntime value and it is thus
very simple: it always tries to run the task with the smallest p->se.vruntime
value (i.e., the task which executed least so far). CFS always tries to split
up CPU time between runnable tasks as close to "ideal multitasking hardware" as
possible.
Most of the rest of CFS's design just falls out of this really simple concept,
with a few add-on embellishments like nice levels, multiprocessing and various
algorithm variants to recognize sleepers.
3. THE RBTREE
CFS's design is quite radical: it does not use the old data structures for the
runqueues, but it uses a time-ordered rbtree to build a "timeline" of future
task execution, and thus has no "array switch" artifacts (by which both the
previous vanilla scheduler and RSDL/SD are affected).
CFS also maintains the rq->cfs.min_vruntime value, which is a monotonic
increasing value tracking the smallest vruntime among all tasks in the
runqueue. The total amount of work done by the system is tracked using
min_vruntime; that value is used to place newly activated entities on the left
side of the tree as much as possible.
The total number of running tasks in the runqueue is accounted through the
rq->cfs.load value, which is the sum of the weights of the tasks queued on the
runqueue.
CFS maintains a time-ordered rbtree, where all runnable tasks are sorted by the
p->se.vruntime key (there is a subtraction using rq->cfs.min_vruntime to
account for possible wraparounds). CFS picks the "leftmost" task from this
tree and sticks to it.
As the system progresses forwards, the executed tasks are put into the tree
more and more to the right --- slowly but surely giving a chance for every task
to become the "leftmost task" and thus get on the CPU within a deterministic
amount of time.
Summing up, CFS works like this: it runs a task a bit, and when the task
schedules (or a scheduler tick happens) the task's CPU usage is "accounted
for": the (small) time it just spent using the physical CPU is added to
p->se.vruntime. Once p->se.vruntime gets high enough so that another task
becomes the "leftmost task" of the time-ordered rbtree it maintains (plus a
small amount of "granularity" distance relative to the leftmost task so that we
do not over-schedule tasks and trash the cache), then the new leftmost task is
picked and the current task is preempted.
4. SOME FEATURES OF CFS
CFS uses nanosecond granularity accounting and does not rely on any jiffies or
other HZ detail. Thus the CFS scheduler has no notion of "timeslices" in the
way the previous scheduler had, and has no heuristics whatsoever. There is
only one central tunable (you have to switch on CONFIG_SCHED_DEBUG):
/proc/sys/kernel/sched_granularity_ns
which can be used to tune the scheduler from "desktop" (i.e., low latencies) to
"server" (i.e., good batching) workloads. It defaults to a setting suitable
for desktop workloads. SCHED_BATCH is handled by the CFS scheduler module too.
Due to its design, the CFS scheduler is not prone to any of the "attacks" that
exist today against the heuristics of the stock scheduler: fiftyp.c, thud.c,
chew.c, ring-test.c, massive_intr.c all work fine and do not impact
interactivity and produce the expected behavior.
The CFS scheduler has a much stronger handling of nice levels and SCHED_BATCH
than the previous vanilla scheduler: both types of workloads are isolated much
more aggressively.
SMP load-balancing has been reworked/sanitized: the runqueue-walking
assumptions are gone from the load-balancing code now, and iterators of the
scheduling modules are used. The balancing code got quite a bit simpler as a
result.
5. Scheduling policies
CFS implements three scheduling policies:
- SCHED_NORMAL (traditionally called SCHED_OTHER): The scheduling
policy that is used for regular tasks.
- SCHED_BATCH: Does not preempt nearly as often as regular tasks
would, thereby allowing tasks to run longer and make better use of
caches but at the cost of interactivity. This is well suited for
batch jobs.
- SCHED_IDLE: This is even weaker than nice 19, but its not a true
idle timer scheduler in order to avoid to get into priority
inversion problems which would deadlock the machine.
SCHED_FIFO/_RR are implemented in sched_rt.c and are as specified by
POSIX.
The command chrt from util-linux-ng 2.13.1.1 can set all of these except
SCHED_IDLE.
6. SCHEDULING CLASSES
The new CFS scheduler has been designed in such a way to introduce "Scheduling
Classes," an extensible hierarchy of scheduler modules. These modules
encapsulate scheduling policy details and are handled by the scheduler core
without the core code assuming too much about them.
sched_fair.c implements the CFS scheduler described above.
sched_rt.c implements SCHED_FIFO and SCHED_RR semantics, in a simpler way than
the previous vanilla scheduler did. It uses 100 runqueues (for all 100 RT
priority levels, instead of 140 in the previous scheduler) and it needs no
expired array.
Scheduling classes are implemented through the sched_class structure, which
contains hooks to functions that must be called whenever an interesting event
occurs.
This is the (partial) list of the hooks:
- enqueue_task(...)
Called when a task enters a runnable state.
It puts the scheduling entity (task) into the red-black tree and
increments the nr_running variable.
- dequeue_tree(...)
When a task is no longer runnable, this function is called to keep the
corresponding scheduling entity out of the red-black tree. It decrements
the nr_running variable.
- yield_task(...)
This function is basically just a dequeue followed by an enqueue, unless the
compat_yield sysctl is turned on; in that case, it places the scheduling
entity at the right-most end of the red-black tree.
- check_preempt_curr(...)
This function checks if a task that entered the runnable state should
preempt the currently running task.
- pick_next_task(...)
This function chooses the most appropriate task eligible to run next.
- set_curr_task(...)
This function is called when a task changes its scheduling class or changes
its task group.
- task_tick(...)
This function is mostly called from time tick functions; it might lead to
process switch. This drives the running preemption.
- task_new(...)
The core scheduler gives the scheduling module an opportunity to manage new
task startup. The CFS scheduling module uses it for group scheduling, while
the scheduling module for a real-time task does not use it.
7. GROUP SCHEDULER EXTENSIONS TO CFS
Normally, the scheduler operates on individual tasks and strives to provide
fair CPU time to each task. Sometimes, it may be desirable to group tasks and
provide fair CPU time to each such task group. For example, it may be
desirable to first provide fair CPU time to each user on the system and then to
each task belonging to a user.
CONFIG_GROUP_SCHED strives to achieve exactly that. It lets tasks to be
grouped and divides CPU time fairly among such groups.
CONFIG_RT_GROUP_SCHED permits to group real-time (i.e., SCHED_FIFO and
SCHED_RR) tasks.
CONFIG_FAIR_GROUP_SCHED permits to group CFS (i.e., SCHED_NORMAL and
SCHED_BATCH) tasks.
At present, there are two (mutually exclusive) mechanisms to group tasks for
CPU bandwidth control purposes:
- Based on user id (CONFIG_USER_SCHED)
With this option, tasks are grouped according to their user id.
- Based on "cgroup" pseudo filesystem (CONFIG_CGROUP_SCHED)
This options needs CONFIG_CGROUPS to be defined, and lets the administrator
create arbitrary groups of tasks, using the "cgroup" pseudo filesystem. See
Documentation/cgroups.txt for more information about this filesystem.
Only one of these options to group tasks can be chosen and not both.
Group scheduler tunables:
When CONFIG_FAIR_USER_SCHED is defined, a directory is created in sysfs for
each new user and a "cpu_share" file is added in that directory.
When CONFIG_USER_SCHED is defined, a directory is created in sysfs for each new
user and a "cpu_share" file is added in that directory.
# cd /sys/kernel/uids
# cat 512/cpu_share # Display user 512's CPU share
@ -155,16 +246,14 @@ each new user and a "cpu_share" file is added in that directory.
2048
#
CPU bandwidth between two users are divided in the ratio of their CPU shares.
For ex: if you would like user "root" to get twice the bandwidth of user
"guest", then set the cpu_share for both the users such that "root"'s
cpu_share is twice "guest"'s cpu_share
CPU bandwidth between two users is divided in the ratio of their CPU shares.
For example: if you would like user "root" to get twice the bandwidth of user
"guest," then set the cpu_share for both the users such that "root"'s cpu_share
is twice "guest"'s cpu_share.
When CONFIG_FAIR_CGROUP_SCHED is defined, a "cpu.shares" file is created
for each group created using the pseudo filesystem. See example steps
below to create task groups and modify their CPU share using the "cgroups"
pseudo filesystem
When CONFIG_CGROUP_SCHED is defined, a "cpu.shares" file is created for each
group created using the pseudo filesystem. See example steps below to create
task groups and modify their CPU share using the "cgroups" pseudo filesystem.
# mkdir /dev/cpuctl
# mount -t cgroup -ocpu none /dev/cpuctl

3
arch/alpha/kernel/smp.c
View File

@ -149,6 +149,9 @@ smp_callin(void)
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
/* inform the notifiers about the new cpu */
notify_cpu_starting(cpuid);
/* Must have completely accurate bogos. */
local_irq_enable();

1
arch/arm/kernel/smp.c
View File

@ -277,6 +277,7 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
/*
* Enable local interrupts.
*/
notify_cpu_starting(cpu);
local_irq_enable();
local_fiq_enable();

1
arch/cris/arch-v32/kernel/smp.c
View File

@ -178,6 +178,7 @@ void __init smp_callin(void)
unmask_irq(IPI_INTR_VECT);
unmask_irq(TIMER0_INTR_VECT);
preempt_disable();
notify_cpu_starting(cpu);
local_irq_enable();
cpu_set(cpu, cpu_online_map);

1
arch/ia64/kernel/smpboot.c
View File

@ -401,6 +401,7 @@ smp_callin (void)
spin_lock(&vector_lock);
/* Setup the per cpu irq handling data structures */
__setup_vector_irq(cpuid);
notify_cpu_starting(cpuid);
cpu_set(cpuid, cpu_online_map);
per_cpu(cpu_state, cpuid) = CPU_ONLINE;
spin_unlock(&vector_lock);

2
arch/m32r/kernel/smpboot.c
View File

@ -498,6 +498,8 @@ static void __init smp_online(void)
{
int cpu_id = smp_processor_id();
notify_cpu_starting(cpu_id);
local_irq_enable();
/* Get our bogomips. */

2
arch/mips/kernel/smp.c
View File

@ -121,6 +121,8 @@ asmlinkage __cpuinit void start_secondary(void)
cpu = smp_processor_id();
cpu_data[cpu].udelay_val = loops_per_jiffy;
notify_cpu_starting(cpu);
mp_ops->smp_finish();
set_cpu_sibling_map(cpu);

1
arch/powerpc/kernel/smp.c
View File

@ -453,6 +453,7 @@ int __devinit start_secondary(void *unused)
secondary_cpu_time_init();
ipi_call_lock();
notify_cpu_starting(cpu);
cpu_set(cpu, cpu_online_map);
/* Update sibling maps */
base = cpu_first_thread_in_core(cpu);

2
arch/s390/kernel/smp.c
View File

@ -585,6 +585,8 @@ int __cpuinit start_secondary(void *cpuvoid)
/* Enable pfault pseudo page faults on this cpu. */
pfault_init();
/* call cpu notifiers */
notify_cpu_starting(smp_processor_id());
/* Mark this cpu as online */
spin_lock(&call_lock);
cpu_set(smp_processor_id(), cpu_online_map);

2
arch/sh/kernel/smp.c
View File

@ -82,6 +82,8 @@ asmlinkage void __cpuinit start_secondary(void)
preempt_disable();
notify_cpu_starting(smp_processor_id());
local_irq_enable();
calibrate_delay();

1
arch/sparc/kernel/sun4d_smp.c
View File

@ -88,6 +88,7 @@ void __init smp4d_callin(void)
local_flush_cache_all();
local_flush_tlb_all();
notify_cpu_starting(cpuid);
/*
* Unblock the master CPU _only_ when the scheduler state
* of all secondary CPUs will be up-to-date, so after

2
arch/sparc/kernel/sun4m_smp.c
View File

@ -71,6 +71,8 @@ void __cpuinit smp4m_callin(void)
local_flush_cache_all();
local_flush_tlb_all();
notify_cpu_starting(cpuid);
/* Get our local ticker going. */
smp_setup_percpu_timer();

1
arch/um/kernel/smp.c
View File

@ -85,6 +85,7 @@ static int idle_proc(void *cpup)
while (!cpu_isset(cpu, smp_commenced_mask))
cpu_relax();
notify_cpu_starting(cpu);
cpu_set(cpu, cpu_online_map);
default_idle();
return 0;

1
arch/x86/kernel/smpboot.c
View File

@ -257,6 +257,7 @@ static void __cpuinit smp_callin(void)
end_local_APIC_setup();
map_cpu_to_logical_apicid();
notify_cpu_starting(cpuid);
/*
* Get our bogomips.
*

2
arch/x86/mach-voyager/voyager_smp.c
View File

@ -448,6 +448,8 @@ static void __init start_secondary(void *unused)
VDEBUG(("VOYAGER SMP: CPU%d, stack at about %p\n", cpuid, &cpuid));
notify_cpu_starting(cpuid);
/* enable interrupts */
local_irq_enable();

41
include/linux/completion.h
View File

@ -10,6 +10,18 @@
#include <linux/wait.h>
/**
* struct completion - structure used to maintain state for a "completion"
*
* This is the opaque structure used to maintain the state for a "completion".
* Completions currently use a FIFO to queue threads that have to wait for
* the "completion" event.
*
* See also: complete(), wait_for_completion() (and friends _timeout,
* _interruptible, _interruptible_timeout, and _killable), init_completion(),
* and macros DECLARE_COMPLETION(), DECLARE_COMPLETION_ONSTACK(), and
* INIT_COMPLETION().
*/
struct completion {
unsigned int done;
wait_queue_head_t wait;
@ -21,6 +33,14 @@ struct completion {
#define COMPLETION_INITIALIZER_ONSTACK(work) \
({ init_completion(&work); work; })
/**
* DECLARE_COMPLETION: - declare and initialize a completion structure
* @work: identifier for the completion structure
*
* This macro declares and initializes a completion structure. Generally used
* for static declarations. You should use the _ONSTACK variant for automatic
* variables.
*/
#define DECLARE_COMPLETION(work) \
struct completion work = COMPLETION_INITIALIZER(work)
@ -29,6 +49,13 @@ struct completion {
* completions - so we use the _ONSTACK() variant for those that
* are on the kernel stack:
*/
/**
* DECLARE_COMPLETION_ONSTACK: - declare and initialize a completion structure
* @work: identifier for the completion structure
*
* This macro declares and initializes a completion structure on the kernel
* stack.
*/
#ifdef CONFIG_LOCKDEP
# define DECLARE_COMPLETION_ONSTACK(work) \
struct completion work = COMPLETION_INITIALIZER_ONSTACK(work)
@ -36,6 +63,13 @@ struct completion {
# define DECLARE_COMPLETION_ONSTACK(work) DECLARE_COMPLETION(work)
#endif
/**
* init_completion: - Initialize a dynamically allocated completion
* @x: completion structure that is to be initialized
*
* This inline function will initialize a dynamically created completion
* structure.
*/
static inline void init_completion(struct completion *x)
{
x->done = 0;
@ -55,6 +89,13 @@ extern bool completion_done(struct completion *x);
extern void complete(struct completion *);
extern void complete_all(struct completion *);
/**
* INIT_COMPLETION: - reinitialize a completion structure
* @x: completion structure to be reinitialized
*
* This macro should be used to reinitialize a completion structure so it can
* be reused. This is especially important after complete_all() is used.
*/
#define INIT_COMPLETION(x) ((x).done = 0)

1
include/linux/cpu.h
View File

@ -69,6 +69,7 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
#endif
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_hotplug_init(void);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);

10
include/linux/notifier.h
View File

@ -213,9 +213,16 @@ static inline int notifier_to_errno(int ret)
#define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */
#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
#define CPU_DYING 0x0008 /* CPU (unsigned)v not running any task,
* not handling interrupts, soon dead */
* not handling interrupts, soon dead.
* Called on the dying cpu, interrupts
* are already disabled. Must not
* sleep, must not fail */
#define CPU_POST_DEAD 0x0009 /* CPU (unsigned)v dead, cpu_hotplug
* lock is dropped */
#define CPU_STARTING 0x000A /* CPU (unsigned)v soon running.
* Called on the new cpu, just before
* enabling interrupts. Must not sleep,
* must not fail */
/* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
* operation in progress
@ -229,6 +236,7 @@ static inline int notifier_to_errno(int ret)
#define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
#define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
#define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN)
#define CPU_STARTING_FROZEN (CPU_STARTING | CPU_TASKS_FROZEN)
/* Hibernation and suspend events */
#define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */

2
include/linux/proportions.h
View File

@ -104,8 +104,8 @@ struct prop_local_single {
* snapshot of the last seen global state
* and a lock protecting this state
*/
int shift;
unsigned long period;
int shift;
spinlock_t lock; /* protect the snapshot state */
};

9
include/linux/sched.h
View File

@ -451,8 +451,8 @@ struct signal_struct {
* - everyone except group_exit_task is stopped during signal delivery
* of fatal signals, group_exit_task processes the signal.
*/
struct task_struct *group_exit_task;
int notify_count;
struct task_struct *group_exit_task;
/* thread group stop support, overloads group_exit_code too */
int group_stop_count;
@ -824,6 +824,9 @@ struct sched_domain {
unsigned int ttwu_move_affine;
unsigned int ttwu_move_balance;
#endif
#ifdef CONFIG_SCHED_DEBUG
char *name;
#endif
};
extern void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
@ -897,7 +900,7 @@ struct sched_class {
void (*yield_task) (struct rq *rq);
int (*select_task_rq)(struct task_struct *p, int sync);
void (*check_preempt_curr) (struct rq *rq, struct task_struct *p);
void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int sync);
struct task_struct * (*pick_next_task) (struct rq *rq);
void (*put_prev_task) (struct rq *rq, struct task_struct *p);
@ -1010,8 +1013,8 @@ struct sched_entity {
struct sched_rt_entity {
struct list_head run_list;
unsigned int time_slice;
unsigned long timeout;
unsigned int time_slice;
int nr_cpus_allowed;
struct sched_rt_entity *back;

24
kernel/cpu.c
View File

@ -199,13 +199,14 @@ static int __ref take_cpu_down(void *_param)
struct take_cpu_down_param *param = _param;
int err;
raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
param->hcpu);
/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
return err;
raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
param->hcpu);
/* Force idle task to run as soon as we yield: it should
immediately notice cpu is offline and die quickly. */
sched_idle_next();
@ -453,6 +454,25 @@ out:
}
#endif /* CONFIG_PM_SLEEP_SMP */
/**
* notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
* @cpu: cpu that just started
*
* This function calls the cpu_chain notifiers with CPU_STARTING.
* It must be called by the arch code on the new cpu, before the new cpu
* enables interrupts and before the "boot" cpu returns from __cpu_up().
*/
void notify_cpu_starting(unsigned int cpu)
{
unsigned long val = CPU_STARTING;
#ifdef CONFIG_PM_SLEEP_SMP
if (cpu_isset(cpu, frozen_cpus))
val = CPU_STARTING_FROZEN;
#endif /* CONFIG_PM_SLEEP_SMP */
raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
}
#endif /* CONFIG_SMP */
/*

2
kernel/cpuset.c
View File

@ -1921,7 +1921,7 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
* that has tasks along with an empty 'mems'. But if we did see such
* a cpuset, we'd handle it just like we do if its 'cpus' was empty.
*/
static void scan_for_empty_cpusets(const struct cpuset *root)
static void scan_for_empty_cpusets(struct cpuset *root)
{
LIST_HEAD(queue);
struct cpuset *cp; /* scans cpusets being updated */

407
kernel/sched.c
View File

@ -204,11 +204,16 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
rt_b->rt_period_timer.cb_mode = HRTIMER_CB_IRQSAFE_UNLOCKED;
}
static inline int rt_bandwidth_enabled(void)
{
return sysctl_sched_rt_runtime >= 0;
}
static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
ktime_t now;
if (rt_b->rt_runtime == RUNTIME_INF)
if (rt_bandwidth_enabled() && rt_b->rt_runtime == RUNTIME_INF)
return;
if (hrtimer_active(&rt_b->rt_period_timer))
@ -298,9 +303,9 @@ static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
#endif /* CONFIG_RT_GROUP_SCHED */
#else /* !CONFIG_FAIR_GROUP_SCHED */
#else /* !CONFIG_USER_SCHED */
#define root_task_group init_task_group
#endif /* CONFIG_FAIR_GROUP_SCHED */
#endif /* CONFIG_USER_SCHED */
/* task_group_lock serializes add/remove of task groups and also changes to
* a task group's cpu shares.
@ -604,9 +609,9 @@ struct rq {
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
static inline void check_preempt_curr(struct rq *rq, struct task_struct *p, int sync)
{
rq->curr->sched_class->check_preempt_curr(rq, p);
rq->curr->sched_class->check_preempt_curr(rq, p, sync);
}
static inline int cpu_of(struct rq *rq)
@ -1102,7 +1107,7 @@ static void hrtick_start(struct rq *rq, u64 delay)
hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), HRTIMER_MODE_REL);
}
static void init_hrtick(void)
static inline void init_hrtick(void)
{
}
#endif /* CONFIG_SMP */
@ -1121,7 +1126,7 @@ static void init_rq_hrtick(struct rq *rq)
rq->hrtick_timer.function = hrtick;
rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_PERCPU;
}
#else
#else /* CONFIG_SCHED_HRTICK */
static inline void hrtick_clear(struct rq *rq)
{
}
@ -1133,7 +1138,7 @@ static inline void init_rq_hrtick(struct rq *rq)
static inline void init_hrtick(void)
{
}
#endif
#endif /* CONFIG_SCHED_HRTICK */
/*
* resched_task - mark a task 'to be rescheduled now'.
@ -1380,6 +1385,51 @@ static inline void dec_cpu_load(struct rq *rq, unsigned long load)
update_load_sub(&rq->load, load);
}
#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
typedef int (*tg_visitor)(struct task_group *, void *);
/*
* Iterate the full tree, calling @down when first entering a node and @up when
* leaving it for the final time.
*/
static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
{
struct task_group *parent, *child;
int ret;
rcu_read_lock();
parent = &root_task_group;
down:
ret = (*down)(parent, data);
if (ret)
goto out_unlock;
list_for_each_entry_rcu(child, &parent->children, siblings) {
parent = child;
goto down;
up:
continue;
}
ret = (*up)(parent, data);
if (ret)
goto out_unlock;
child = parent;
parent = parent->parent;
if (parent)
goto up;
out_unlock:
rcu_read_unlock();
return ret;
}
static int tg_nop(struct task_group *tg, void *data)
{
return 0;
}
#endif
#ifdef CONFIG_SMP
static unsigned long source_load(int cpu, int type);
static unsigned long target_load(int cpu, int type);
@ -1397,37 +1447,6 @@ static unsigned long cpu_avg_load_per_task(int cpu)
#ifdef CONFIG_FAIR_GROUP_SCHED
typedef void (*tg_visitor)(struct task_group *, int, struct sched_domain *);
/*
* Iterate the full tree, calling @down when first entering a node and @up when
* leaving it for the final time.
*/
static void
walk_tg_tree(tg_visitor down, tg_visitor up, int cpu, struct sched_domain *sd)
{
struct task_group *parent, *child;
rcu_read_lock();
parent = &root_task_group;
down:
(*down)(parent, cpu, sd);
list_for_each_entry_rcu(child, &parent->children, siblings) {
parent = child;
goto down;
up:
continue;
}
(*up)(parent, cpu, sd);
child = parent;
parent = parent->parent;
if (parent)
goto up;
rcu_read_unlock();
}
static void __set_se_shares(struct sched_entity *se, unsigned long shares);
/*
@ -1486,11 +1505,11 @@ __update_group_shares_cpu(struct task_group *tg, int cpu,
* This needs to be done in a bottom-up fashion because the rq weight of a
* parent group depends on the shares of its child groups.
*/
static void
tg_shares_up(struct task_group *tg, int cpu, struct sched_domain *sd)
static int tg_shares_up(struct task_group *tg, void *data)
{
unsigned long rq_weight = 0;
unsigned long shares = 0;
struct sched_domain *sd = data;
int i;
for_each_cpu_mask(i, sd->span) {
@ -1515,6 +1534,8 @@ tg_shares_up(struct task_group *tg, int cpu, struct sched_domain *sd)
__update_group_shares_cpu(tg, i, shares, rq_weight);
spin_unlock_irqrestore(&rq->lock, flags);
}
return 0;
}
/*
@ -1522,10 +1543,10 @@ tg_shares_up(struct task_group *tg, int cpu, struct sched_domain *sd)
* This needs to be done in a top-down fashion because the load of a child
* group is a fraction of its parents load.
*/
static void
tg_load_down(struct task_group *tg, int cpu, struct sched_domain *sd)
static int tg_load_down(struct task_group *tg, void *data)
{
unsigned long load;
long cpu = (long)data;
if (!tg->parent) {
load = cpu_rq(cpu)->load.weight;
@ -1536,11 +1557,8 @@ tg_load_down(struct task_group *tg, int cpu, struct sched_domain *sd)
}
tg->cfs_rq[cpu]->h_load = load;
}
static void
tg_nop(struct task_group *tg, int cpu, struct sched_domain *sd)
{
return 0;
}
static void update_shares(struct sched_domain *sd)
@ -1550,7 +1568,7 @@ static void update_shares(struct sched_domain *sd)
if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
sd->last_update = now;
walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
walk_tg_tree(tg_nop, tg_shares_up, sd);
}
}
@ -1561,9 +1579,9 @@ static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
spin_lock(&rq->lock);
}
static void update_h_load(int cpu)
static void update_h_load(long cpu)
{
walk_tg_tree(tg_load_down, tg_nop, cpu, NULL);
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
}
#else
@ -1921,11 +1939,8 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
running = task_running(rq, p);
on_rq = p->se.on_rq;
ncsw = 0;
if (!match_state || p->state == match_state) {
ncsw = p->nivcsw + p->nvcsw;
if (unlikely(!ncsw))
ncsw = 1;
}
if (!match_state || p->state == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
task_rq_unlock(rq, &flags);
/*
@ -2285,7 +2300,7 @@ out_running:
trace_mark(kernel_sched_wakeup,
"pid %d state %ld ## rq %p task %p rq->curr %p",
p->pid, p->state, rq, p, rq->curr);
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, sync);
p->state = TASK_RUNNING;
#ifdef CONFIG_SMP
@ -2420,7 +2435,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
trace_mark(kernel_sched_wakeup_new,
"pid %d state %ld ## rq %p task %p rq->curr %p",
p->pid, p->state, rq, p, rq->curr);
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, 0);
#ifdef CONFIG_SMP
if (p->sched_class->task_wake_up)
p->sched_class->task_wake_up(rq, p);
@ -2880,7 +2895,7 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
* Note that idle threads have a prio of MAX_PRIO, for this test
* to be always true for them.
*/
check_preempt_curr(this_rq, p);
check_preempt_curr(this_rq, p, 0);
}
/*
@ -4627,6 +4642,15 @@ __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
}
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
/**
* complete: - signals a single thread waiting on this completion
* @x: holds the state of this particular completion
*
* This will wake up a single thread waiting on this completion. Threads will be
* awakened in the same order in which they were queued.
*
* See also complete_all(), wait_for_completion() and related routines.
*/
void complete(struct completion *x)
{
unsigned long flags;
@ -4638,6 +4662,12 @@ void complete(struct completion *x)
}
EXPORT_SYMBOL(complete);
/**
* complete_all: - signals all threads waiting on this completion
* @x: holds the state of this particular completion
*
* This will wake up all threads waiting on this particular completion event.
*/
void complete_all(struct completion *x)
{
unsigned long flags;
@ -4658,10 +4688,7 @@ do_wait_for_common(struct completion *x, long timeout, int state)
wait.flags |= WQ_FLAG_EXCLUSIVE;
__add_wait_queue_tail(&x->wait, &wait);
do {
if ((state == TASK_INTERRUPTIBLE &&
signal_pending(current)) ||
(state == TASK_KILLABLE &&
fatal_signal_pending(current))) {
if (signal_pending_state(state, current)) {
timeout = -ERESTARTSYS;
break;
}
@ -4689,12 +4716,31 @@ wait_for_common(struct completion *x, long timeout, int state)
return timeout;
}
/**
* wait_for_completion: - waits for completion of a task
* @x: holds the state of this particular completion
*
* This waits to be signaled for completion of a specific task. It is NOT
* interruptible and there is no timeout.
*
* See also similar routines (i.e. wait_for_completion_timeout()) with timeout
* and interrupt capability. Also see complete().
*/
void __sched wait_for_completion(struct completion *x)
{
wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(wait_for_completion);
/**
* wait_for_completion_timeout: - waits for completion of a task (w/timeout)
* @x: holds the state of this particular completion
* @timeout: timeout value in jiffies
*
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. The timeout is in jiffies. It is not
* interruptible.
*/
unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
{
@ -4702,6 +4748,13 @@ wait_for_completion_timeout(struct completion *x, unsigned long timeout)
}
EXPORT_SYMBOL(wait_for_completion_timeout);
/**
* wait_for_completion_interruptible: - waits for completion of a task (w/intr)
* @x: holds the state of this particular completion
*
* This waits for completion of a specific task to be signaled. It is
* interruptible.
*/
int __sched wait_for_completion_interruptible(struct completion *x)
{
long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
@ -4711,6 +4764,14 @@ int __sched wait_for_completion_interruptible(struct completion *x)
}
EXPORT_SYMBOL(wait_for_completion_interruptible);
/**
* wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
* @x: holds the state of this particular completion
* @timeout: timeout value in jiffies
*
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. It is interruptible. The timeout is in jiffies.
*/
unsigned long __sched
wait_for_completion_interruptible_timeout(struct completion *x,
unsigned long timeout)
@ -4719,6 +4780,13 @@ wait_for_completion_interruptible_timeout(struct completion *x,
}
EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
/**
* wait_for_completion_killable: - waits for completion of a task (killable)
* @x: holds the state of this particular completion
*
* This waits to be signaled for completion of a specific task. It can be
* interrupted by a kill signal.
*/
int __sched wait_for_completion_killable(struct completion *x)
{
long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
@ -5121,7 +5189,8 @@ recheck:
* Do not allow realtime tasks into groups that have no runtime
* assigned.
*/
if (rt_policy(policy) && task_group(p)->rt_bandwidth.rt_runtime == 0)
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0)
return -EPERM;
#endif
@ -5957,7 +6026,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
set_task_cpu(p, dest_cpu);
if (on_rq) {
activate_task(rq_dest, p, 0);
check_preempt_curr(rq_dest, p);
check_preempt_curr(rq_dest, p, 0);
}
done:
ret = 1;
@ -6282,7 +6351,7 @@ set_table_entry(struct ctl_table *entry,
static struct ctl_table *
sd_alloc_ctl_domain_table(struct sched_domain *sd)
{
struct ctl_table *table = sd_alloc_ctl_entry(12);
struct ctl_table *table = sd_alloc_ctl_entry(13);
if (table == NULL)
return NULL;
@ -6310,7 +6379,9 @@ sd_alloc_ctl_domain_table(struct sched_domain *sd)
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[10], "flags", &sd->flags,
sizeof(int), 0644, proc_dointvec_minmax);
/* &table[11] is terminator */
set_table_entry(&table[11], "name", sd->name,
CORENAME_MAX_SIZE, 0444, proc_dostring);
/* &table[12] is terminator */
return table;
}
@ -7194,13 +7265,21 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
* Non-inlined to reduce accumulated stack pressure in build_sched_domains()
*/
#ifdef CONFIG_SCHED_DEBUG
# define SD_INIT_NAME(sd, type) sd->name = #type
#else
# define SD_INIT_NAME(sd, type) do { } while (0)
#endif
#define SD_INIT(sd, type) sd_init_##type(sd)
#define SD_INIT_FUNC(type) \
static noinline void sd_init_##type(struct sched_domain *sd) \
{ \
memset(sd, 0, sizeof(*sd)); \
*sd = SD_##type##_INIT; \
sd->level = SD_LV_##type; \
SD_INIT_NAME(sd, type); \
}
SD_INIT_FUNC(CPU)
@ -8242,20 +8321,25 @@ void __might_sleep(char *file, int line)
#ifdef in_atomic
static unsigned long prev_jiffy; /* ratelimiting */
if ((in_atomic() || irqs_disabled()) &&
system_state == SYSTEM_RUNNING && !oops_in_progress) {
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;
printk(KERN_ERR "BUG: sleeping function called from invalid"
" context at %s:%d\n", file, line);
printk("in_atomic():%d, irqs_disabled():%d\n",
in_atomic(), irqs_disabled());
debug_show_held_locks(current);
if (irqs_disabled())
print_irqtrace_events(current);
dump_stack();
}
if ((!in_atomic() && !irqs_disabled()) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;
printk(KERN_ERR
"BUG: sleeping function called from invalid context at %s:%d\n",
file, line);
printk(KERN_ERR
"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
in_atomic(), irqs_disabled(),
current->pid, current->comm);
debug_show_held_locks(current);
if (irqs_disabled())
print_irqtrace_events(current);
dump_stack();
#endif
}
EXPORT_SYMBOL(__might_sleep);
@ -8753,75 +8837,97 @@ static DEFINE_MUTEX(rt_constraints_mutex);
static unsigned long to_ratio(u64 period, u64 runtime)
{
if (runtime == RUNTIME_INF)
return 1ULL << 16;
return 1ULL << 20;
return div64_u64(runtime << 16, period);
return div64_u64(runtime << 20, period);
}
#ifdef CONFIG_CGROUP_SCHED
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
struct task_group *tgi, *parent = tg->parent;
unsigned long total = 0;
if (!parent) {
if (global_rt_period() < period)
return 0;
return to_ratio(period, runtime) <
to_ratio(global_rt_period(), global_rt_runtime());
}
if (ktime_to_ns(parent->rt_bandwidth.rt_period) < period)
return 0;
rcu_read_lock();
list_for_each_entry_rcu(tgi, &parent->children, siblings) {
if (tgi == tg)
continue;
total += to_ratio(ktime_to_ns(tgi->rt_bandwidth.rt_period),
tgi->rt_bandwidth.rt_runtime);
}
rcu_read_unlock();
return total + to_ratio(period, runtime) <=
to_ratio(ktime_to_ns(parent->rt_bandwidth.rt_period),
parent->rt_bandwidth.rt_runtime);
}
#elif defined CONFIG_USER_SCHED
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
struct task_group *tgi;
unsigned long total = 0;
unsigned long global_ratio =
to_ratio(global_rt_period(), global_rt_runtime());
rcu_read_lock();
list_for_each_entry_rcu(tgi, &task_groups, list) {
if (tgi == tg)
continue;
total += to_ratio(ktime_to_ns(tgi->rt_bandwidth.rt_period),
tgi->rt_bandwidth.rt_runtime);
}
rcu_read_unlock();
return total + to_ratio(period, runtime) < global_ratio;
}
#endif
/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
{
struct task_struct *g, *p;
do_each_thread(g, p) {
if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
return 1;
} while_each_thread(g, p);
return 0;
}
struct rt_schedulable_data {
struct task_group *tg;
u64 rt_period;
u64 rt_runtime;
};
static int tg_schedulable(struct task_group *tg, void *data)
{
struct rt_schedulable_data *d = data;
struct task_group *child;
unsigned long total, sum = 0;
u64 period, runtime;
period = ktime_to_ns(tg->rt_bandwidth.rt_period);
runtime = tg->rt_bandwidth.rt_runtime;
if (tg == d->tg) {
period = d->rt_period;
runtime = d->rt_runtime;
}
/*
* Cannot have more runtime than the period.
*/
if (runtime > period && runtime != RUNTIME_INF)
return -EINVAL;
/*
* Ensure we don't starve existing RT tasks.
*/
if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
return -EBUSY;
total = to_ratio(period, runtime);
/*
* Nobody can have more than the global setting allows.
*/
if (total > to_ratio(global_rt_period(), global_rt_runtime()))
return -EINVAL;
/*
* The sum of our children's runtime should not exceed our own.
*/
list_for_each_entry_rcu(child, &tg->children, siblings) {
period = ktime_to_ns(child->rt_bandwidth.rt_period);
runtime = child->rt_bandwidth.rt_runtime;
if (child == d->tg) {
period = d->rt_period;
runtime = d->rt_runtime;
}
sum += to_ratio(period, runtime);
}
if (sum > total)
return -EINVAL;
return 0;
}
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
struct rt_schedulable_data data = {
.tg = tg,
.rt_period = period,
.rt_runtime = runtime,
};
return walk_tg_tree(tg_schedulable, tg_nop, &data);
}
static int tg_set_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
@ -8829,14 +8935,9 @@ static int tg_set_bandwidth(struct task_group *tg,
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
if (rt_runtime == 0 && tg_has_rt_tasks(tg)) {
err = -EBUSY;
err = __rt_schedulable(tg, rt_period, rt_runtime);
if (err)
goto unlock;
}
if (!__rt_schedulable(tg, rt_period, rt_runtime)) {
err = -EINVAL;
goto unlock;
}
spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
@ -8905,19 +9006,25 @@ long sched_group_rt_period(struct task_group *tg)
static int sched_rt_global_constraints(void)
{
struct task_group *tg = &root_task_group;
u64 rt_runtime, rt_period;
u64 runtime, period;
int ret = 0;
if (sysctl_sched_rt_period <= 0)
return -EINVAL;
rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
rt_runtime = tg->rt_bandwidth.rt_runtime;
runtime = global_rt_runtime();
period = global_rt_period();
/*
* Sanity check on the sysctl variables.
*/
if (runtime > period && runtime != RUNTIME_INF)
return -EINVAL;
mutex_lock(&rt_constraints_mutex);
if (!__rt_schedulable(tg, rt_period, rt_runtime))
ret = -EINVAL;
read_lock(&tasklist_lock);
ret = __rt_schedulable(NULL, 0, 0);
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return ret;
@ -8991,7 +9098,6 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
if (!cgrp->parent) {
/* This is early initialization for the top cgroup */
init_task_group.css.cgroup = cgrp;
return &init_task_group.css;
}
@ -9000,9 +9106,6 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
if (IS_ERR(tg))
return ERR_PTR(-ENOMEM);
/* Bind the cgroup to task_group object we just created */
tg->css.cgroup = cgrp;
return &tg->css;
}

234
kernel/sched_fair.c
View File

@ -408,64 +408,6 @@ static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
return __sched_period(nr_running);
}
/*
* The goal of calc_delta_asym() is to be asymmetrically around NICE_0_LOAD, in
* that it favours >=0 over <0.
*
* -20 |
* |
* 0 --------+-------
* .'
* 19 .'
*
*/
static unsigned long
calc_delta_asym(unsigned long delta, struct sched_entity *se)
{
struct load_weight lw = {
.weight = NICE_0_LOAD,
.inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT)
};
for_each_sched_entity(se) {
struct load_weight *se_lw = &se->load;
unsigned long rw = cfs_rq_of(se)->load.weight;
#ifdef CONFIG_FAIR_SCHED_GROUP
struct cfs_rq *cfs_rq = se->my_q;
struct task_group *tg = NULL
if (cfs_rq)
tg = cfs_rq->tg;
if (tg && tg->shares < NICE_0_LOAD) {
/*
* scale shares to what it would have been had
* tg->weight been NICE_0_LOAD:
*
* weight = 1024 * shares / tg->weight
*/
lw.weight *= se->load.weight;
lw.weight /= tg->shares;
lw.inv_weight = 0;
se_lw = &lw;
rw += lw.weight - se->load.weight;
} else
#endif
if (se->load.weight < NICE_0_LOAD) {
se_lw = &lw;
rw += NICE_0_LOAD - se->load.weight;
}
delta = calc_delta_mine(delta, rw, se_lw);
}
return delta;
}
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@ -586,11 +528,12 @@ account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
update_load_add(&cfs_rq->load, se->load.weight);
if (!parent_entity(se))
inc_cpu_load(rq_of(cfs_rq), se->load.weight);
if (entity_is_task(se))
if (entity_is_task(se)) {
add_cfs_task_weight(cfs_rq, se->load.weight);
list_add(&se->group_node, &cfs_rq->tasks);
}
cfs_rq->nr_running++;
se->on_rq = 1;
list_add(&se->group_node, &cfs_rq->tasks);
}
static void
@ -599,11 +542,12 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
update_load_sub(&cfs_rq->load, se->load.weight);
if (!parent_entity(se))
dec_cpu_load(rq_of(cfs_rq), se->load.weight);
if (entity_is_task(se))
if (entity_is_task(se)) {
add_cfs_task_weight(cfs_rq, -se->load.weight);
list_del_init(&se->group_node);
}
cfs_rq->nr_running--;
se->on_rq = 0;
list_del_init(&se->group_node);
}
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
@ -1085,7 +1029,6 @@ static long effective_load(struct task_group *tg, int cpu,
long wl, long wg)
{
struct sched_entity *se = tg->se[cpu];
long more_w;
if (!tg->parent)
return wl;
@ -1097,18 +1040,17 @@ static long effective_load(struct task_group *tg, int cpu,
if (!wl && sched_feat(ASYM_EFF_LOAD))
return wl;
/*
* Instead of using this increment, also add the difference
* between when the shares were last updated and now.
*/
more_w = se->my_q->load.weight - se->my_q->rq_weight;
wl += more_w;
wg += more_w;
for_each_sched_entity(se) {
#define D(n) (likely(n) ? (n) : 1)
long S, rw, s, a, b;
long more_w;
/*
* Instead of using this increment, also add the difference
* between when the shares were last updated and now.
*/
more_w = se->my_q->load.weight - se->my_q->rq_weight;
wl += more_w;
wg += more_w;
S = se->my_q->tg->shares;
s = se->my_q->shares;
@ -1117,7 +1059,11 @@ static long effective_load(struct task_group *tg, int cpu,
a = S*(rw + wl);
b = S*rw + s*wg;
wl = s*(a-b)/D(b);
wl = s*(a-b);
if (likely(b))
wl /= b;
/*
* Assume the group is already running and will
* thus already be accounted for in the weight.
@ -1126,7 +1072,6 @@ static long effective_load(struct task_group *tg, int cpu,
* alter the group weight.
*/
wg = 0;
#undef D
}
return wl;
@ -1143,7 +1088,7 @@ static inline unsigned long effective_load(struct task_group *tg, int cpu,
#endif
static int
wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
struct task_struct *p, int prev_cpu, int this_cpu, int sync,
int idx, unsigned long load, unsigned long this_load,
unsigned int imbalance)
@ -1158,6 +1103,11 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
return 0;
if (!sync && sched_feat(SYNC_WAKEUPS) &&
curr->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost)
sync = 1;
/*
* If sync wakeup then subtract the (maximum possible)
* effect of the currently running task from the load
@ -1182,17 +1132,14 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
* a reasonable amount of time then attract this newly
* woken task:
*/
if (sync && balanced) {
if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost)
return 1;
}
if (sync && balanced)
return 1;
schedstat_inc(p, se.nr_wakeups_affine_attempts);
tl_per_task = cpu_avg_load_per_task(this_cpu);
if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
balanced) {
if (balanced || (tl <= load && tl + target_load(prev_cpu, idx) <=
tl_per_task)) {
/*
* This domain has SD_WAKE_AFFINE and
* p is cache cold in this domain, and
@ -1211,16 +1158,17 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
struct sched_domain *sd, *this_sd = NULL;
int prev_cpu, this_cpu, new_cpu;
unsigned long load, this_load;
struct rq *rq, *this_rq;
struct rq *this_rq;
unsigned int imbalance;
int idx;
prev_cpu = task_cpu(p);
rq = task_rq(p);
this_cpu = smp_processor_id();
this_rq = cpu_rq(this_cpu);
new_cpu = prev_cpu;
if (prev_cpu == this_cpu)
goto out;
/*
* 'this_sd' is the first domain that both
* this_cpu and prev_cpu are present in:
@ -1248,13 +1196,10 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
load = source_load(prev_cpu, idx);
this_load = target_load(this_cpu, idx);
if (wake_affine(rq, this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
if (wake_affine(this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
load, this_load, imbalance))
return this_cpu;
if (prev_cpu == this_cpu)
goto out;
/*
* Start passive balancing when half the imbalance_pct
* limit is reached.
@ -1281,62 +1226,20 @@ static unsigned long wakeup_gran(struct sched_entity *se)
* + nice tasks.
*/
if (sched_feat(ASYM_GRAN))
gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se);
else
gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se);
gran = calc_delta_mine(gran, NICE_0_LOAD, &se->load);
return gran;
}
/*
* Should 'se' preempt 'curr'.
*
* |s1
* |s2
* |s3
* g
* |<--->|c
*
* w(c, s1) = -1
* w(c, s2) = 0
* w(c, s3) = 1
*
*/
static int
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
{
s64 gran, vdiff = curr->vruntime - se->vruntime;
if (vdiff < 0)
return -1;
gran = wakeup_gran(curr);
if (vdiff > gran)
return 1;
return 0;
}
/* return depth at which a sched entity is present in the hierarchy */
static inline int depth_se(struct sched_entity *se)
{
int depth = 0;
for_each_sched_entity(se)
depth++;
return depth;
}
/*
* Preempt the current task with a newly woken task if needed:
*/
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
{
struct task_struct *curr = rq->curr;
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
struct sched_entity *se = &curr->se, *pse = &p->se;
int se_depth, pse_depth;
s64 delta_exec;
if (unlikely(rt_prio(p->prio))) {
update_rq_clock(rq);
@ -1350,6 +1253,13 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
cfs_rq_of(pse)->next = pse;
/*
* We can come here with TIF_NEED_RESCHED already set from new task
* wake up path.
*/
if (test_tsk_need_resched(curr))
return;
/*
* Batch tasks do not preempt (their preemption is driven by
* the tick):
@ -1360,33 +1270,15 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
if (!sched_feat(WAKEUP_PREEMPT))
return;
/*
* preemption test can be made between sibling entities who are in the
* same cfs_rq i.e who have a common parent. Walk up the hierarchy of
* both tasks until we find their ancestors who are siblings of common
* parent.
*/
/* First walk up until both entities are at same depth */
se_depth = depth_se(se);
pse_depth = depth_se(pse);
while (se_depth > pse_depth) {
se_depth--;
se = parent_entity(se);
if (sched_feat(WAKEUP_OVERLAP) && (sync ||
(se->avg_overlap < sysctl_sched_migration_cost &&
pse->avg_overlap < sysctl_sched_migration_cost))) {
resched_task(curr);
return;
}
while (pse_depth > se_depth) {
pse_depth--;
pse = parent_entity(pse);
}
while (!is_same_group(se, pse)) {
se = parent_entity(se);
pse = parent_entity(pse);
}
if (wakeup_preempt_entity(se, pse) == 1)
delta_exec = se->sum_exec_runtime - se->prev_sum_exec_runtime;
if (delta_exec > wakeup_gran(pse))
resched_task(curr);
}
@ -1445,19 +1337,9 @@ __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
if (next == &cfs_rq->tasks)
return NULL;
/* Skip over entities that are not tasks */
do {
se = list_entry(next, struct sched_entity, group_node);
next = next->next;
} while (next != &cfs_rq->tasks && !entity_is_task(se));
if (next == &cfs_rq->tasks)
return NULL;
cfs_rq->balance_iterator = next;
if (entity_is_task(se))
p = task_of(se);
se = list_entry(next, struct sched_entity, group_node);
p = task_of(se);
cfs_rq->balance_iterator = next->next;
return p;
}
@ -1507,7 +1389,7 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
rcu_read_lock();
update_h_load(busiest_cpu);
list_for_each_entry(tg, &task_groups, list) {
list_for_each_entry_rcu(tg, &task_groups, list) {
struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
unsigned long busiest_h_load = busiest_cfs_rq->h_load;
unsigned long busiest_weight = busiest_cfs_rq->load.weight;
@ -1620,10 +1502,10 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
* 'current' within the tree based on its new key value.
*/
swap(curr->vruntime, se->vruntime);
resched_task(rq->curr);
}
enqueue_task_fair(rq, p, 0);
resched_task(rq->curr);
}
/*
@ -1642,7 +1524,7 @@ static void prio_changed_fair(struct rq *rq, struct task_struct *p,
if (p->prio > oldprio)
resched_task(rq->curr);
} else
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, 0);
}
/*
@ -1659,7 +1541,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p,
if (running)
resched_task(rq->curr);
else
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, 0);
}
/* Account for a task changing its policy or group.

1
kernel/sched_features.h
View File

@ -11,3 +11,4 @@ SCHED_FEAT(ASYM_GRAN, 1)
SCHED_FEAT(LB_BIAS, 1)
SCHED_FEAT(LB_WAKEUP_UPDATE, 1)
SCHED_FEAT(ASYM_EFF_LOAD, 1)
SCHED_FEAT(WAKEUP_OVERLAP, 0)

6
kernel/sched_idletask.c
View File

@ -14,7 +14,7 @@ static int select_task_rq_idle(struct task_struct *p, int sync)
/*
* Idle tasks are unconditionally rescheduled:
*/
static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int sync)
{
resched_task(rq->idle);
}
@ -76,7 +76,7 @@ static void switched_to_idle(struct rq *rq, struct task_struct *p,
if (running)
resched_task(rq->curr);
else
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, 0);
}
static void prio_changed_idle(struct rq *rq, struct task_struct *p,
@ -93,7 +93,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p,
if (p->prio > oldprio)
resched_task(rq->curr);
} else
check_preempt_curr(rq, p);
check_preempt_curr(rq, p, 0);
}
/*

57
kernel/sched_rt.c
View File

@ -102,12 +102,12 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
struct sched_rt_entity *rt_se = rt_rq->rt_se;
if (rt_se && !on_rt_rq(rt_se) && rt_rq->rt_nr_running) {
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
enqueue_rt_entity(rt_se);
if (rt_rq->rt_nr_running) {
if (rt_se && !on_rt_rq(rt_se))
enqueue_rt_entity(rt_se);
if (rt_rq->highest_prio < curr->prio)
resched_task(curr);
}
@ -231,6 +231,9 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_SMP
/*
* We ran out of runtime, see if we can borrow some from our neighbours.
*/
static int do_balance_runtime(struct rt_rq *rt_rq)
{
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
@ -250,9 +253,18 @@ static int do_balance_runtime(struct rt_rq *rt_rq)
continue;
spin_lock(&iter->rt_runtime_lock);
/*
* Either all rqs have inf runtime and there's nothing to steal
* or __disable_runtime() below sets a specific rq to inf to
* indicate its been disabled and disalow stealing.
*/
if (iter->rt_runtime == RUNTIME_INF)
goto next;
/*
* From runqueues with spare time, take 1/n part of their
* spare time, but no more than our period.
*/
diff = iter->rt_runtime - iter->rt_time;
if (diff > 0) {
diff = div_u64((u64)diff, weight);
@ -274,6 +286,9 @@ next:
return more;
}
/*
* Ensure this RQ takes back all the runtime it lend to its neighbours.
*/
static void __disable_runtime(struct rq *rq)
{
struct root_domain *rd = rq->rd;
@ -289,17 +304,33 @@ static void __disable_runtime(struct rq *rq)
spin_lock(&rt_b->rt_runtime_lock);
spin_lock(&rt_rq->rt_runtime_lock);
/*
* Either we're all inf and nobody needs to borrow, or we're
* already disabled and thus have nothing to do, or we have
* exactly the right amount of runtime to take out.
*/
if (rt_rq->rt_runtime == RUNTIME_INF ||
rt_rq->rt_runtime == rt_b->rt_runtime)
goto balanced;
spin_unlock(&rt_rq->rt_runtime_lock);
/*
* Calculate the difference between what we started out with
* and what we current have, that's the amount of runtime
* we lend and now have to reclaim.
*/
want = rt_b->rt_runtime - rt_rq->rt_runtime;
/*
* Greedy reclaim, take back as much as we can.
*/
for_each_cpu_mask(i, rd->span) {
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
s64 diff;
/*
* Can't reclaim from ourselves or disabled runqueues.
*/
if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
continue;
@ -319,8 +350,16 @@ static void __disable_runtime(struct rq *rq)
}
spin_lock(&rt_rq->rt_runtime_lock);
/*
* We cannot be left wanting - that would mean some runtime
* leaked out of the system.
*/
BUG_ON(want);
balanced:
/*
* Disable all the borrow logic by pretending we have inf
* runtime - in which case borrowing doesn't make sense.
*/
rt_rq->rt_runtime = RUNTIME_INF;
spin_unlock(&rt_rq->rt_runtime_lock);
spin_unlock(&rt_b->rt_runtime_lock);
@ -343,6 +382,9 @@ static void __enable_runtime(struct rq *rq)
if (unlikely(!scheduler_running))
return;
/*
* Reset each runqueue's bandwidth settings
*/
for_each_leaf_rt_rq(rt_rq, rq) {
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
@ -389,7 +431,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
int i, idle = 1;
cpumask_t span;
if (rt_b->rt_runtime == RUNTIME_INF)
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return 1;
span = sched_rt_period_mask();
@ -487,6 +529,9 @@ static void update_curr_rt(struct rq *rq)
curr->se.exec_start = rq->clock;
cpuacct_charge(curr, delta_exec);
if (!rt_bandwidth_enabled())
return;
for_each_sched_rt_entity(rt_se) {
rt_rq = rt_rq_of_se(rt_se);
@ -784,7 +829,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
/*
* Preempt the current task with a newly woken task if needed:
*/
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int sync)
{
if (p->prio < rq->curr->prio) {
resched_task(rq->curr);

4
kernel/user.c
View File

@ -169,7 +169,7 @@ static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
return sprintf(buf, "%lu\n", sched_group_rt_runtime(up->tg));
return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
}
static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
@ -180,7 +180,7 @@ static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
unsigned long rt_runtime;
int rc;
sscanf(buf, "%lu", &rt_runtime);
sscanf(buf, "%ld", &rt_runtime);
rc = sched_group_set_rt_runtime(up->tg, rt_runtime);