Subject: Re: [RFC 0/12][PATCH] SCHED_DEADLINE: core of the scheduling class
From: Peter Zijlstra <peterz@infradead.org>
To: Raistlin <raistlin@linux.it>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       michael trimarchi <michael@evidence.eu.com>,
       Fabio Checconi <fabio@gandalf.sssup.it>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>,
       Dhaval Giani <dhaval.giani@gmail.com>,
       Johan Eker <johan.eker@ericsson.com>, "p.faure" <p.faure@akatech.ch>,
       Chris Friesen <cfriesen@nortel.com>,
       Steven Rostedt <rostedt@goodmis.org>, Henrik Austad <henrik@austad.us>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Darren Hart <darren@dvhart.com>,
       Sven-Thorsten Dietrich <sven@thebigcorporation.com>,
       Bjoern Brandenburg <bbb@cs.unc.edu>,
       Tommaso Cucinotta <tommaso.cucinotta@sssup.it>,
       "giuseppe.lipari" <giuseppe.lipari@sssup.it>,
       Juri Lelli <juri.lelli@gmail.com>
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Date: Tue, 29 Dec 2009 13:25:38 +0100
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On Fri, 2009-10-16 at 17:40 +0200, Raistlin wrote:
> @@ -5966,10 +5982,14 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
>         if (running)
>                 p->sched_class->put_prev_task(rq, p);
>  
> -       if (rt_prio(prio))
> -               p->sched_class = &rt_sched_class;
> -       else
> -               p->sched_class = &fair_sched_class;
> +       if (deadline_task(p))
> +               p->sched_class = &deadline_sched_class;
> +       else {
> +               if (rt_prio(prio))
> +                       p->sched_class = &rt_sched_class;
> +               else
> +                       p->sched_class = &fair_sched_class;
> +       } 

This looks wrong.

This is PI code, so the effective class should be determined based on
the 'priority' not on the 'policy'.

I understand we don't yet have deadline inheritance like things in
place, but this would be where we should make use of the simple ceiling
protocol to boost things for now.


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