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sched, x86: Optimize the preempt_schedule() call

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Remove the bloat of the C calling convention out of the
preempt_enable() sites by creating an ASM wrapper which allows us to
do an asm("call ___preempt_schedule") instead.

calling.h bits by Andi Kleen

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-tk7xdi1cvvxewixzke8t8le1@git.kernel.org
[ Fixed build error. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2013-08-14 14:51:00 +02:00 • committed by Ingo Molnar
commit 1a338ac32c
8 changed files with 116 additions and 8 deletions
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13
include/linux/preempt.h
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@ -50,18 +50,17 @@ do { \
#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
#ifdef CONFIG_PREEMPT
asmlinkage void preempt_schedule(void);
#define preempt_enable() \
do { \
barrier(); \
if (unlikely(preempt_count_dec_and_test())) \
preempt_schedule(); \
__preempt_schedule(); \
} while (0)
#define preempt_check_resched() \
do { \
if (should_resched()) \
preempt_schedule(); \
__preempt_schedule(); \
} while (0)
#else
@ -83,17 +82,15 @@ do { \
#ifdef CONFIG_PREEMPT
#ifdef CONFIG_CONTEXT_TRACKING
asmlinkage void preempt_schedule_context(void);
#else
#define preempt_schedule_context() preempt_schedule()
#ifndef CONFIG_CONTEXT_TRACKING
#define __preempt_schedule_context() __preempt_schedule()
#endif
#define preempt_enable_notrace() \
do { \
barrier(); \
if (unlikely(__preempt_count_dec_and_test())) \
preempt_schedule_context(); \
__preempt_schedule_context(); \
} while (0)
#else
#define preempt_enable_notrace() preempt_enable_no_resched_notrace()