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sched: optimize cond_resched()

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Optimize cond_resched() by removing one conditional.

Currently cond_resched() checks system_state ==
SYSTEM_RUNNING in order to avoid scheduling before the
scheduler is running.

We can however, as per suggestion of Matt, use
PREEMPT_ACTIVE to accomplish that very same.

Suggested-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra
2009-07-10 14:57:57 +02:00
committed by Linus Torvalds
parent c99e6efe1b
commit d86ee4809d
2 changed files with 13 additions and 6 deletions
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5
include/linux/sched.h
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@@ -501,8 +501,11 @@ struct task_cputime {
/*
* Disable preemption until the scheduler is running.
* Reset by start_kernel()->sched_init()->init_idle().
*
* We include PREEMPT_ACTIVE to avoid cond_resched() from working
* before the scheduler is active -- see should_resched().
*/
#define INIT_PREEMPT_COUNT (1)
#define INIT_PREEMPT_COUNT (1 + PREEMPT_ACTIVE)
/**
* struct thread_group_cputimer - thread group interval timer counts