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authorChen Shang <shangcs@gmail.com>2005-06-25 14:57:31 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:44 -0700
commita3464a102a69a4e00efb0a763e274ce290995b4b (patch)
tree63a9301d4a02dfcefd8dff70f033c634aa93bb2f /kernel/sched.c
parent77391d71681d05d2f4502f91ad62618522abf624 (diff)
[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.c19
1 files changed, 12 insertions, 7 deletions
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: