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sched: optimize schedule() a bit on SMP

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optimize schedule() a bit on SMP, by moving the rq-clock update
outside the rq lock.

code size is the same:

      text    data     bss     dec     hex filename
     25725    2666      96   28487    6f47 sched.o.before
     25725    2666      96   28487    6f47 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2007-10-15 17:00:13 +02:00
parent 08ec3df510
commit 1e81995066
1 changed files with 6 additions and 2 deletions
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8
kernel/sched.c
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@ -3481,9 +3481,13 @@ need_resched_nonpreemptible:
schedule_debug(prev); schedule_debug(prev);
spin_lock_irq(&rq->lock); /*
clear_tsk_need_resched(prev); * Do the rq-clock update outside the rq lock:
*/
local_irq_disable();
__update_rq_clock(rq); __update_rq_clock(rq);
spin_lock(&rq->lock);
clear_tsk_need_resched(prev);
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely((prev->state & TASK_INTERRUPTIBLE) && if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&