On Wed, 4 Apr 2007 22:05:40 +0200 "Dmitry Adamushko" <[email protected]> wrote:
> Ingo,
>
> following the conversation on "a redundant reschedule call in set_user_prio()",
> here is a possible approach.
>
> The patch is somewhat intrusive as it even dares to adapt TASK_PREEMPTS_CURR().
>
> Nevertheless, this adaptation seems to be ok with all the current use-cases.
>
> Presupposition: TASK_PREEMPTS_CURR(p, rq) will /never/ be used as "a
> mere prio comparator" - e.g. to make decisions on which array a task
> has to be placed in.
>
>
> =====
>
> o Make TASK_PREEMPTS_CURR(task, rq) return "true" only if the task's
> prio is higher than the current's one and the task is in the "active"
> array.
> This ensures we don't make redundant resched_task() calls when the
> task is in the "expired" array (as may happen now in set_user_prio(),
> rt_mutex_setprio() and pull_task() ) ;
>
> o generilise conditions for a call to resched_task() in
> set_user_nice(), rt_mutex_setprio() and sched_setscheduler()
>
grief. This patch conflicts seriously with the staircase scheduler in -mm.
So to merge it I need to
- apply it
- then apply a revert-it-again patch
- then apply staircase
- then ask Con to cook up a staircase-based equivalent of your change.
so
- your code only gets publically tested in its against-staircase version
- the against-mainline version will get merged without having been
publically tested outside of staircase
which is probably all OK for a 2.6.22-rc1 thing, provided Ingo can give a
confident ack.
Where are we at with staircase anyway? Is it looking like a 2.6.22 thing?
I don't personally think we've yet seen enough serious performance testing
to permit a merge, apart from other issues...
> --- linux-2.6.21-rc5/kernel/sched-orig.c 2007-04-04
> 18:26:19.000000000 +0200
> +++ linux-2.6.21-rc5/kernel/sched.c 2007-04-04 18:26:43.000000000 +0200
> @@ -168,7 +168,7 @@ unsigned long long __attribute__((weak))
> (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
>
> #define TASK_PREEMPTS_CURR(p, rq) \
> - ((p)->prio < (rq)->curr->prio)
> + (((p)->prio < (rq)->curr->prio) && ((p)->array == (rq)->active))
Your patch was wordwrapped and had its tabs replaced with spaces. Please
fix your email client.
(I might as well make that paragraph my .signature)
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