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Commit 35a773a0 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Avoid _cond_resched() for PREEMPT=y 



On fully preemptible kernels _cond_resched() is pointless, so avoid
emitting any code for it.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9af6528e

include/linux/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -3209,7 +3209,11 @@ static inline int signal_pending_state(long state, struct task_struct *p) 
 * cond_resched_lock() will drop the spinlock before scheduling,

 * cond_resched_softirq() will enable bhs before scheduling.

 */

#ifndef CONFIG_PREEMPT

extern int _cond_resched(void);

#else

static inline int _cond_resched(void) { return 0; }

#endif



#define cond_resched() ({			\

	___might_sleep(__FILE__, __LINE__, 0);	\

kernel/sched/core.c

+2 −0
Original line number Diff line number Diff line
@@ -4883,6 +4883,7 @@ SYSCALL_DEFINE0(sched_yield) 
	return 0;

}



#ifndef CONFIG_PREEMPT

int __sched _cond_resched(void)

{

	if (should_resched(0)) {
@@ -4892,6 +4893,7 @@ int __sched _cond_resched(void) 
	return 0;

}

EXPORT_SYMBOL(_cond_resched);

#endif



/*

 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,