sched: Separate the scheduler entry for preemption (c259e01a) · Commits · 戴 / test

Block-IO and workqueues call into notifier functions from the scheduler core code with interrupts and preemption disabled. These calls should be made before entering the scheduler core. To simplify this, separate the scheduler core code into __schedule(). __schedule() is directly called from the places which set PREEMPT_ACTIVE and from schedule(). This allows us to add the work checks into schedule(), so they are only called when a task voluntary goes to sleep. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@kernel.org # 2.6.39+ Link: http://lkml.kernel.org/r/20110622174918.813258321@linutronix.de Signed-off-by:

Ingo Molnar <mingo@elte.hu>

kernel/sched.c

+10 −5

Original line number	Diff line number	Diff line
		@@ -4279,9 +4279,9 @@ pick_next_task(struct rq *rq)
		}

		/*
		* schedule() is the main scheduler function.
		* __schedule() is the main scheduler function.
		*/
		asmlinkage void __sched schedule(void)
		static void __sched __schedule(void)
		{
		struct task_struct prev, next;
		unsigned long *switch_count;
		@@ -4369,6 +4369,11 @@ need_resched:
		if (need_resched())
		goto need_resched;
		}

		asmlinkage void schedule(void)
		{
		__schedule();
		}
		EXPORT_SYMBOL(schedule);

		#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
		@@ -4435,7 +4440,7 @@ asmlinkage void __sched notrace preempt_schedule(void)

		do {
		add_preempt_count_notrace(PREEMPT_ACTIVE);
		schedule();
		__schedule();
		sub_preempt_count_notrace(PREEMPT_ACTIVE);

		/*
		@@ -4463,7 +4468,7 @@ asmlinkage void __sched preempt_schedule_irq(void)
		do {
		add_preempt_count(PREEMPT_ACTIVE);
		local_irq_enable();
		schedule();
		__schedule();
		local_irq_disable();
		sub_preempt_count(PREEMPT_ACTIVE);

		@@ -5588,7 +5593,7 @@ static inline int should_resched(void)
		static void __cond_resched(void)
		{
		add_preempt_count(PREEMPT_ACTIVE);
		schedule();
		__schedule();
		sub_preempt_count(PREEMPT_ACTIVE);
		}

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