From: Chen Shang Date: Sat, 25 Jun 2005 21:57:31 +0000 (-0700) Subject: [PATCH] sched: micro-optimize task requeueing in schedule() X-Git-Tag: v2.6.13-rc1~68^2~138 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=a3464a102a69a4e00efb0a763e274ce290995b4b;p=linux-2.6-omap-h63xx.git [PATCH] sched: micro-optimize task requeueing in schedule() micro-optimize task requeueing in schedule() & clean up recalc_task_prio(). Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/sched.c b/kernel/sched.c index 6e452eb95ac..a3d1c8e43d3 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -673,7 +673,7 @@ static inline void __activate_idle_task(task_t *p, runqueue_t *rq) rq->nr_running++; } -static void recalc_task_prio(task_t *p, unsigned long long now) +static int recalc_task_prio(task_t *p, unsigned long long now) { /* Caller must always ensure 'now >= p->timestamp' */ unsigned long long __sleep_time = now - p->timestamp; @@ -732,7 +732,7 @@ static void recalc_task_prio(task_t *p, unsigned long long now) } } - p->prio = effective_prio(p); + return effective_prio(p); } /* @@ -755,7 +755,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local) } #endif - recalc_task_prio(p, now); + p->prio = recalc_task_prio(p, now); /* * This checks to make sure it's not an uninterruptible task @@ -2751,7 +2751,7 @@ asmlinkage void __sched schedule(void) struct list_head *queue; unsigned long long now; unsigned long run_time; - int cpu, idx; + int cpu, idx, new_prio; /* * Test if we are atomic. Since do_exit() needs to call into @@ -2873,9 +2873,14 @@ go_idle: delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128; array = next->array; - dequeue_task(next, array); - recalc_task_prio(next, next->timestamp + delta); - enqueue_task(next, array); + new_prio = recalc_task_prio(next, next->timestamp + delta); + + if (unlikely(next->prio != new_prio)) { + dequeue_task(next, array); + next->prio = new_prio; + enqueue_task(next, array); + } else + requeue_task(next, array); } next->activated = 0; switch_tasks: