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| author | Chen Shang <shangcs@gmail.com> | 2005-06-25 14:57:31 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-25 16:24:44 -0700 |
| commit | a3464a102a69a4e00efb0a763e274ce290995b4b (patch) | |
| tree | 63a9301d4a02dfcefd8dff70f033c634aa93bb2f /kernel/sched.c | |
| parent | 77391d71681d05d2f4502f91ad62618522abf624 (diff) | |
| download | lwn-a3464a102a69a4e00efb0a763e274ce290995b4b.tar.gz lwn-a3464a102a69a4e00efb0a763e274ce290995b4b.zip | |
[PATCH] sched: micro-optimize task requeueing in schedule()
micro-optimize task requeueing in schedule() & clean up recalc_task_prio().
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 6e452eb95ac3..a3d1c8e43d34 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: |