linux-kernel - Re: [sched] redundant reschedule when set_user_nice() boosts a prio of a task from the "expired" array

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Date:	Wed, 4 Apr 2007 17:23:59 +0200
From:	"Dmitry Adamushko" <dmitry.adamushko@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [sched] redundant reschedule when set_user_nice() boosts a prio of a task from the "expired" array

On 04/04/07, Ingo Molnar <mingo@...e.hu> wrote:
>
> * Dmitry Adamushko <dmitry.adamushko@...il.com> wrote:
> > [...]
> >
> > The same is applicable to rt_mutex_setprio().
> >
> > Of course, not a big deal, but it's easily avoidable, e.g. (delta < 0
> > && array == rq->active).
>
> i think you are right and a micro-optimization could be done here. Would
> you like to do a patch for this?

Yes, I'll do it.

in fact, "delta < 0 && array == rq->active" is also sub-optimal.

"TASK_PREEMPTS_CURR(p, rq) && array == rq->active" seems to be ok.. or
maybe even TASK_PREEMPTS_CURR() should internally check for "p->array
== rq->active"...

will come with some solution.

Thanks.

>
>         Ingo
>

-- 
Best regards,
Dmitry Adamushko
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