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sched/preempt: Optimize preemption operations on __schedule() callers

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__schedule() disables preemption and some of its callers
(the preempt_schedule*() family) also set PREEMPT_ACTIVE.

So we have two preempt_count() modifications that could be performed
at once.

Lets remove the preemption disablement from __schedule() and pull
this responsibility to its callers in order to optimize preempt_count()
operations in a single place.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431441711-29753-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Frederic Weisbecker 2015-05-12 16:41:49 +02:00 • committed by Ingo Molnar
parent 90b62b5129
commit b30f0e3ffe
2 changed files with 21 additions and 20 deletions
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12
include/linux/preempt.h
View file

@ -137,6 +137,18 @@ extern void preempt_count_sub(int val);
#define preempt_count_inc() preempt_count_add(1)
#define preempt_count_dec() preempt_count_sub(1)
#define preempt_active_enter() \
do { \
preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
barrier(); \
} while (0)
#define preempt_active_exit() \
do { \
barrier(); \
preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
} while (0)
#ifdef CONFIG_PREEMPT_COUNT
#define preempt_disable() \