From: Peter Zijlstra <peterz@infradead.org>
To: Scott Wood <swood@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Rik van Riel <riel@surriel.com>, Mel Gorman <mgorman@suse.de>,
linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Subject: Re: [RFC PATCH 1/3] sched/fair: Call newidle_balance() from finish_task_switch()
Date: Wed, 29 Apr 2020 01:02:04 +0200 [thread overview]
Message-ID: <20200428230204.GE16027@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c4a8d1f044b721a2c396fa00a0244eff0b851ae4.camel@redhat.com>
On Tue, Apr 28, 2020 at 05:55:03PM -0500, Scott Wood wrote:
> On Wed, 2020-04-29 at 00:09 +0200, Peter Zijlstra wrote:
> > Also, if you move it this late, this is entirely the wrong place. If you
> > do it after the context switch either use the balance_callback or put it
> > in the idle path.
> >
> > But what Valentin said; this needs a fair bit of support, the whole
> > reason we've never done this is to avoid that double context switch...
> >
>
> balance_callback() enters with the rq lock held but BH not separately
BH? softirqs you mean? Pray tell more.
> disabled, which interferes with the ability to enable interrupts but not BH.
> It also gets called from rt_mutex_setprio() and __sched_setscheduler(), and
> I didn't want the caller of those to be stuck with the latency.
You're not reading it right.
next prev parent reply other threads:[~2020-04-28 23:02 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 5:02 [RFC PATCH 0/3] newidle_balance() latency mitigation Scott Wood
2020-04-28 5:02 ` [RFC PATCH 1/3] sched/fair: Call newidle_balance() from finish_task_switch() Scott Wood
2020-04-28 21:37 ` Valentin Schneider
2020-04-28 22:09 ` Peter Zijlstra
2020-04-28 22:55 ` Scott Wood
2020-04-28 23:02 ` Peter Zijlstra [this message]
2020-04-28 23:20 ` Scott Wood
2020-04-29 9:05 ` Peter Zijlstra
2020-04-30 1:31 ` Scott Wood
2020-05-11 10:58 ` Peter Zijlstra
2020-05-11 12:13 ` Peter Zijlstra
2020-04-28 22:33 ` Scott Wood
2020-04-29 12:00 ` Valentin Schneider
2020-04-29 8:27 ` Vincent Guittot
2020-04-30 1:36 ` Scott Wood
2020-04-28 5:02 ` [RFC PATCH 2/3] sched/fair: Enable interrupts when dropping lock in newidle_balance() Scott Wood
2020-04-28 5:02 ` [RFC PATCH 3/3] sched,rt: break out of load balancing if an RT task appears Scott Wood
2020-04-28 21:56 ` Valentin Schneider
2020-04-28 22:33 ` Scott Wood
2020-04-28 22:52 ` Scott Wood
2020-04-29 12:01 ` Valentin Schneider
2020-04-28 13:27 ` [RFC PATCH 0/3] newidle_balance() latency mitigation Steven Rostedt
2020-04-29 23:13 ` Valentin Schneider
2020-04-30 7:44 ` Vincent Guittot
2020-04-30 10:14 ` Valentin Schneider
2020-04-30 12:42 ` Vincent Guittot
2020-04-30 13:56 ` Valentin Schneider
2020-04-30 12:48 ` Vincent Guittot
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