From: Peter Zijlstra <peterz@infradead.org>
To: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
"open list:THERMAL" <linux-pm@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: Re: [PATCH] sched/fair: schedutil: update only with all info available
Date: Wed, 11 Apr 2018 17:14:50 +0200 [thread overview]
Message-ID: <20180411151450.GK4043@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180410110412.GG14248@e110439-lin>
On Tue, Apr 10, 2018 at 12:04:12PM +0100, Patrick Bellasi wrote:
> On 09-Apr 10:51, Vincent Guittot wrote:
> > Peter,
> > what was your goal with adding the condition "if
> > (rq->cfs.h_nr_running)" for the aggragation of CFS utilization
>
> The original intent was to get rid of sched class flags, used to track
> which class has tasks runnable from within schedutil. The reason was
> to solve some misalignment between scheduler class status and
> schedutil status.
>
> The solution, initially suggested by Viresh, and finally proposed by
> Peter was to exploit RQ knowledges directly from within schedutil.
>
> The problem is that now schedutil updated depends on two information:
> utilization changes and number of RT and CFS runnable tasks.
>
> Thus, using cfs_rq::h_nr_running is not the problem... it's actually
> part of a much more clean solution of the code we used to have.
>
> The problem, IMO is that we now depend on other information which
> needs to be in sync before calling schedutil... and the patch I
> proposed is meant to make it less likely that all the information
> required are not aligned (also in the future).
Specifically, the h_nr_running test was get rid of
if (delta_ns > TICK_NSEC) {
j_sg_cpu->iowait_boost = 0;
j_sg_cpu->iowait_boost_pending = false;
- j_sg_cpu->util_cfs = 0;
^^^^^^^^^^^^^^^^^^^^^^^ that..
- if (j_sg_cpu->util_dl == 0)
- continue;
}
because that felt rather arbitrary.
next prev parent reply other threads:[~2018-04-11 15:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-06 17:28 [PATCH] sched/fair: schedutil: update only with all info available Patrick Bellasi
2018-04-06 23:48 ` Joel Fernandes
2018-04-10 11:44 ` Patrick Bellasi
2018-04-09 8:51 ` Vincent Guittot
2018-04-10 11:04 ` Patrick Bellasi
2018-04-11 6:57 ` Vincent Guittot
2018-04-11 10:15 ` Patrick Bellasi
2018-04-11 11:56 ` Vincent Guittot
2018-04-11 14:33 ` Patrick Bellasi
2018-04-11 21:34 ` Joel Fernandes
2018-04-12 7:01 ` Vincent Guittot
2018-04-12 18:06 ` Joel Fernandes
2018-04-11 15:14 ` Peter Zijlstra [this message]
2018-04-11 15:29 ` Vincent Guittot
2018-04-11 15:37 ` Peter Zijlstra
2018-04-11 15:41 ` Vincent Guittot
2018-04-11 16:00 ` Peter Zijlstra
2018-04-11 16:10 ` Vincent Guittot
2018-04-11 16:15 ` Peter Zijlstra
2018-04-11 16:51 ` Vincent Guittot
2018-04-26 11:15 ` Patrick Bellasi
2018-04-26 11:52 ` Peter Zijlstra
2018-04-11 7:57 ` Vincent Guittot
2018-04-11 9:27 ` Patrick Bellasi
2018-04-11 14:53 ` Peter Zijlstra
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