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Commit ff743345 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: remove extra call overhead for schedule() 



Lai Jiangshan's patch reminded me that I promised Nick to remove
that extra call overhead in schedule().

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090313112300.927414207@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 13318a71

kernel/mutex.c

+3 −1
Original line number Diff line number Diff line
@@ -248,7 +248,9 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 


		/* didnt get the lock, go to sleep: */

		spin_unlock_mutex(&lock->wait_lock, flags);

		__schedule();

		preempt_enable_no_resched();

		schedule();

		preempt_disable();

		spin_lock_mutex(&lock->wait_lock, flags);

	}

kernel/sched.c

+4 −8
Original line number Diff line number Diff line
@@ -5131,13 +5131,15 @@ pick_next_task(struct rq *rq) 
/*

 * schedule() is the main scheduler function.

 */

asmlinkage void __sched __schedule(void)

asmlinkage void __sched schedule(void)

{

	struct task_struct *prev, *next;

	unsigned long *switch_count;

	struct rq *rq;

	int cpu;



need_resched:

	preempt_disable();

	cpu = smp_processor_id();

	rq = cpu_rq(cpu);

	rcu_qsctr_inc(cpu);
@@ -5194,15 +5196,9 @@ need_resched_nonpreemptible: 


	if (unlikely(reacquire_kernel_lock(current) < 0))

		goto need_resched_nonpreemptible;

}



asmlinkage void __sched schedule(void)

{

need_resched:

	preempt_disable();

	__schedule();

	preempt_enable_no_resched();

	if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))

	if (need_resched())

		goto need_resched;

}

EXPORT_SYMBOL(schedule);