From: Chen Shang <shangcs@gmail.com>
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>
---
kernel/sched.c | 19 ++++++++++++-------
1 files changed, 12 insertions(+), 7 deletions(-)
diff -puN kernel/sched.c~sched-micro-optimize-task-requeueing-in-schedule kernel/sched.c
--- 25/kernel/sched.c~sched-micro-optimize-task-requeueing-in-schedule 2005-06-18 02:55:38.000000000 -0700
+++ 25-akpm/kernel/sched.c 2005-06-18 02:55:38.000000000 -0700
@@ -675,7 +675,7 @@ static inline void __activate_idle_task(
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;
@@ -734,7 +734,7 @@ static void recalc_task_prio(task_t *p,
}
}
- p->prio = effective_prio(p);
+ return effective_prio(p);
}
/*
@@ -757,7 +757,7 @@ static void activate_task(task_t *p, run
}
#endif
- recalc_task_prio(p, now);
+ p->prio = recalc_task_prio(p, now);
/*
* This checks to make sure it's not an uninterruptible task
@@ -2753,7 +2753,7 @@ 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
@@ -2875,9 +2875,14 @@ 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:
_