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| author | Hugo Lefeuvre <hle@owl.eu.com> | 2019-02-07 21:03:52 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-02-11 08:34:04 +0100 |
| commit | 2b9c2a4859ad5ac7b5a28e9db28c3e618760fe8c (patch) | |
| tree | aa5d4435267ee9206a36ef3fd5abbfec7ce83893 /include/linux/wait.h | |
| parent | 9f132742d5c4146397fef0c5b09fe220576a5bb2 (diff) | |
| download | linux-2b9c2a4859ad5ac7b5a28e9db28c3e618760fe8c.tar.gz linux-2b9c2a4859ad5ac7b5a28e9db28c3e618760fe8c.tar.bz2 linux-2b9c2a4859ad5ac7b5a28e9db28c3e618760fe8c.zip | |
sched/wait: Use freezable_schedule() when possible
Replace 'schedule(); try_to_freeze();' with a call to freezable_schedule().
Tasks calling freezable_schedule() set the PF_FREEZER_SKIP flag
before calling schedule(). Unlike tasks calling schedule();
try_to_freeze() tasks calling freezable_schedule() are not awaken by
try_to_freeze_tasks(). Instead they call try_to_freeze() when they
wake up if the freeze is still underway.
It is not a problem since sleeping tasks can't do anything which isn't
allowed for a frozen task while sleeping.
The result is a potential performance gain during freeze, since less
tasks have to be awaken.
For instance on a bare Debian vm running a 4.19 stable kernel, the
number of tasks skipped in freeze_task() went up from 12 without the
patch to 32 with the patch (out of 448), an increase of > x2.5.
Signed-off-by: Hugo Lefeuvre <hle@owl.eu.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190207200352.GA27859@behemoth.owl.eu.com.local
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/wait.h')
| -rw-r--r-- | include/linux/wait.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h index ed7c122cb31f..5f3efabc36f4 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -308,7 +308,7 @@ do { \ #define __wait_event_freezable(wq_head, condition) \ ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0, \ - schedule(); try_to_freeze()) + freezable_schedule()) /** * wait_event_freezable - sleep (or freeze) until a condition gets true @@ -367,7 +367,7 @@ do { \ #define __wait_event_freezable_timeout(wq_head, condition, timeout) \ ___wait_event(wq_head, ___wait_cond_timeout(condition), \ TASK_INTERRUPTIBLE, 0, timeout, \ - __ret = schedule_timeout(__ret); try_to_freeze()) + __ret = freezable_schedule_timeout(__ret)) /* * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid @@ -588,7 +588,7 @@ do { \ #define __wait_event_freezable_exclusive(wq, condition) \ ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0, \ - schedule(); try_to_freeze()) + freezable_schedule()) #define wait_event_freezable_exclusive(wq, condition) \ ({ \ |