sched: optimize schedule() a bit on SMP
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>
diff --git a/kernel/sched.c b/kernel/sched.c
index e717047..4f13d37 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3481,9 +3481,13 @@
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);
+ spin_lock(&rq->lock);
+ clear_tsk_need_resched(prev);
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&