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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-07-10 14:57:57 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-10 14:24:05 -0700 |
| commit | d86ee4809d0329d4aa0d0f2c76c2295a16862799 (patch) | |
| tree | 32b3eaf766c1127ef2298c2e48b5441b7cf9b843 /include/linux | |
| parent | c99e6efe1ba04561e7d93a81f0be07e37427e835 (diff) | |
| download | blackbird-op-linux-d86ee4809d0329d4aa0d0f2c76c2295a16862799.tar.gz blackbird-op-linux-d86ee4809d0329d4aa0d0f2c76c2295a16862799.zip | |
sched: optimize cond_resched()
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>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/sched.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 2a99f1c15cf8..16a982e389fb 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -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 |
