Re: [patch] Real-Time Preemption, -RT-2.6.12-rc6-V0.7.48-00

[Ingo Molnar <mingo@elte.hu>]

* Michal Schmidt <xschmi00@stud.feec.vutbr.cz> wrote:

> Hi Ingo,
> 
> Since the introduction of the delayed preemption feature in V0.7.47-20 
> my KDE desktop has been jerky. The sound from artsd often skips. The 
> mouse pointer jumps when I compile anything the background and try to 
> browse the web with Firefox.

yeah.

> I think that try_to_wake_up is broken for the !sync case. We have:
> 
> 		__activate_task(p, rq);
>                 if (TASK_PREEMPTS_CURR(p, rq)) {
>                         if (sync)
>                                 set_tsk_need_resched_delayed(rq->curr);
>                         else
>                                 resched_task(rq->curr);
>                 }
> 
> Shouldn't we call the full activate_task(...) instead of 
> __activate_task(...) in the !sync case?

indeed.

> The attached patch fixes seems to fix it for me. It is against 
> V0.7.48-05.

thanks, applied - but this does not end all of the reschedule problems 
that the latest patches have. More on that later.

	Ingo
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