Messages in this thread Patch in this message | | | Date | Sat, 06 Nov 2004 21:35:20 +1100 | From | Con Kolivas <> | Subject | [PATCH] [sched-int-changes 3/5] add_requeue_task |
| |
add_requeue_task
Please include in at least one -mm release.
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>
Index: linux-2.6.10-rc1-mm3/kernel/sched.c =================================================================== --- linux-2.6.10-rc1-mm3.orig/kernel/sched.c 2004-11-05 20:56:46.608179150 +1100 +++ linux-2.6.10-rc1-mm3/kernel/sched.c 2004-11-05 20:57:14.376900024 +1100 @@ -593,6 +593,15 @@ static void enqueue_task(struct task_str } /* + * 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: @@ -2456,8 +2465,7 @@ void scheduler_tick(void) 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; } @@ -3605,8 +3613,14 @@ 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 [unhandled content-type:application/pgp-signature] | |