linux-kernel - Re: [PATCH] kernel/sched/rt: Add a rescheduling point

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Message-ID: <20170124151745.GM3093@worktop>
Date:   Tue, 24 Jan 2017 16:17:45 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, Juri Lelli <juri.lelli@...il.com>
Subject: Re: [PATCH] kernel/sched/rt: Add a rescheduling point

On Tue, Jan 24, 2017 at 03:43:54PM +0100, Sebastian Andrzej Siewior wrote:
> On 2017-01-24 15:40:06 [+0100], To Peter Zijlstra wrote:
> > Since the change in commit fd7a4bed1835 ("sched, rt: Convert
> > switched_{from, to}_rt() / prio_changed_rt() to balance callbacks") we
> > don't reschedule a task under certain circumstances:
> 
> |switched_to_dl()
> |{
> |…
> |         if (rq->curr != p) {
> | #ifdef CONFIG_SMP
> |                 if (tsk_nr_cpus_allowed(p) > 1 && rq->dl.overloaded)
> |                         queue_push_tasks(rq);
> | #else
> |                 if (dl_task(rq->curr))
> |                         check_preempt_curr_dl(rq, p, 0);
> |                 else
> |                         resched_curr(rq);
> | #endif
> |         }
> | }
> 
> This looks like it asks for a similar change.

Indeed.