diff options
| author | Con Kolivas <kernel@kolivas.org> | 2005-01-07 21:46:13 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-01-07 21:46:13 -0800 |
| commit | 482288d8785689476c947b9c65e642c540ca2e4f (patch) | |
| tree | 6b064cbbef8027cf6656fcc89f0005fbf9141bde /kernel | |
| parent | b53c4efb5fe348108f4d3aa7ef9c5e72d0287b26 (diff) | |
| download | history-482288d8785689476c947b9c65e642c540ca2e4f.tar.gz | |
[PATCH] sched: add_requeue_task
We can requeue tasks for cheaper then doing a complete dequeue followed by
an enqueue. Add the requeue_task function and perform it where possible.
This will be hit frequently by upcoming changes to the requeueing in
timeslice granularity.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-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')
| -rw-r--r-- | kernel/sched.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 2efcc7c5b1fbd1..225193a8a4713e 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -600,6 +600,15 @@ static void enqueue_task(struct task_struct *p, prio_array_t *array) } /* + * Put task to the end of the run list without the overhead of dequeue + * followed by enqueue. + */ +static void requeue_task(struct task_struct *p, prio_array_t *array) +{ + list_move_tail(&p->run_list, array->queue + p->prio); +} + +/* * Used by the migration code - we pull tasks from the head of the * remote queue so we want these tasks to show up at the head of the * local queue: @@ -2348,8 +2357,7 @@ void scheduler_tick(int user_ticks, int sys_ticks) set_tsk_need_resched(p); /* put it at the end of the queue: */ - dequeue_task(p, rq->active); - enqueue_task(p, rq->active); + requeue_task(p, rq->active); } goto out_unlock; } @@ -3441,8 +3449,14 @@ asmlinkage long sys_sched_yield(void) } else if (!rq->expired->nr_active) schedstat_inc(rq, yld_exp_empty); - dequeue_task(current, array); - enqueue_task(current, target); + if (array != target) { + dequeue_task(current, array); + enqueue_task(current, target); + } else + /* + * requeue_task is cheaper so perform that if possible. + */ + requeue_task(current, array); /* * Since we are going to call schedule() anyway, there's |