From: Juri Lelli <juri.lelli@arm.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: peterz@infradead.org, mingo@redhat.com, viresh.kumar@linaro.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
tglx@linutronix.de, vincent.guittot@linaro.org,
rostedt@goodmis.org, luca.abeni@santannapisa.it,
claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it,
bristot@redhat.com, mathieu.poirier@linaro.org,
tkjos@android.com, joelaf@google.com, andresoportus@google.com,
morten.rasmussen@arm.com, dietmar.eggemann@arm.com,
patrick.bellasi@arm.com, Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFD PATCH 4/5] sched/cpufreq_schedutil: always consider all CPUs when deciding next freq
Date: Thu, 30 Mar 2017 09:58:05 +0100 [thread overview]
Message-ID: <20170330085805.GF18960@e106622-lin> (raw)
In-Reply-To: <2348394.hDdCk9fbgK@aspire.rjw.lan>
Hi,
On 30/03/17 00:41, Rafael J. Wysocki wrote:
> On Friday, March 24, 2017 02:08:59 PM Juri Lelli wrote:
> > No assumption can be made upon the rate at which frequency updates get
> > triggered, as there are scheduling policies (like SCHED_DEADLINE) which
> > don't trigger them so frequently.
> >
> > Remove such assumption from the code.
>
> But the util/max values for idle CPUs may be stale, no?
>
Right, that might be a problem. A proper solution I think would be to
remotely update such values for idle CPUs, and I believe Vincent is
working on a patch for that.
As mid-term workarounds, changing a bit the current one, come to my
mind:
- consider TICK_NSEC (continue) only when SCHED_CPUFREQ_DL is not set
- remove CFS contribution (without triggering a freq update) when a CPU
enters IDLE; this might not work well, though, as we probably want
to keep in blocked util contribution for a bit
What you think is the way to go?
Thanks,
- Juri
next prev parent reply other threads:[~2017-03-30 8:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-24 14:08 [RFD PATCH 0/5] SCHED_DEADLINE freq/cpu invariance and OPP selection Juri Lelli
2017-03-24 14:08 ` [RFD PATCH 1/5] sched/cpufreq_schedutil: make use of DEADLINE utilization signal Juri Lelli
2017-03-24 14:08 ` [RFD PATCH 2/5] sched/deadline: move cpu frequency selection triggering points Juri Lelli
2017-03-24 14:08 ` [RFD PATCH 3/5] sched/cpufreq_schedutil: make worker kthread be SCHED_DEADLINE Juri Lelli
2017-03-27 16:50 ` Peter Zijlstra
2017-03-27 17:01 ` Juri Lelli
2017-03-27 17:05 ` Rafael J. Wysocki
2017-03-27 17:13 ` Juri Lelli
2017-03-27 17:37 ` Rafael J. Wysocki
2017-03-27 18:09 ` Mark Brown
2017-03-30 15:50 ` Vikram Mulukutla
2017-03-30 20:22 ` Rafael J. Wysocki
2017-03-31 7:26 ` Juri Lelli
2017-03-27 18:05 ` Mark Brown
2017-03-28 9:29 ` Vincent Guittot
2017-03-28 10:20 ` Peter Zijlstra
2017-03-24 14:08 ` [RFD PATCH 4/5] sched/cpufreq_schedutil: always consider all CPUs when deciding next freq Juri Lelli
2017-03-29 22:41 ` Rafael J. Wysocki
2017-03-30 8:58 ` Juri Lelli [this message]
2017-03-30 13:21 ` Vincent Guittot
2017-03-30 20:13 ` Rafael J. Wysocki
2017-03-31 7:31 ` Juri Lelli
2017-03-31 9:03 ` Rafael J. Wysocki
2017-03-31 9:16 ` Juri Lelli
2017-03-24 14:09 ` [RFD PATCH 5/5] sched/deadline: make bandwidth enforcement scale-invariant Juri Lelli
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