From: Michael Turquette <mturquette@baylibre.com>
To: Steve Muckle <steve.muckle@linaro.org>,
Juri Lelli <Juri.Lelli@arm.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, morten.rasmussen@arm.com,
dietmar.eggemann@arm.com, vincent.guittot@linaro.org,
Michael Turquette <mturquette+renesas@baylibre.com>,
Patrick Bellasi <patrick.bellasi@arm.com>
Subject: Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable
Date: Wed, 16 Mar 2016 15:05:06 -0700 [thread overview]
Message-ID: <20160316220506.11016.7525@quark.deferred.io> (raw)
In-Reply-To: <56E99E25.9070002@linaro.org>
Quoting Steve Muckle (2016-03-16 10:55:49)
> On 03/16/2016 03:02 AM, Juri Lelli wrote:
> > Hi,
> >
> > On 16/03/16 09:05, Peter Zijlstra wrote:
> >> On Tue, Mar 15, 2016 at 08:36:57PM -0700, Steve Muckle wrote:
> >>>> Then again, maybe this knob will be part of the mythical
> >>>> power-vs-performance slider?
> >>>
> >>> Patrick Bellasi's schedtune series [0] (which I think is the referenced
> >>> mythical slider) aims to provide a more sophisticated interface for
> >>> tuning scheduler-driven frequency selection. In addition to a global
> >>> boost value it includes a cgroup controller as well for per-task tuning.
> >>>
> >>> I would definitely expect the margin/boost value to be modified at
> >>> runtime, for example if the battery is running low, or the user wants
> >>> 100% performance for a while, or the userspace framework wants to
> >>> temporarily tailor the performance level for a particular set of tasks, etc.
> >>
> >> OK, so how about we start with it as a debug knob, and once we have
> >> experience and feel like it is indeed a useful runtime knob, we upgrade
> >> it to ABI.
> >>
> >
> > I tend to agree here. To me the margin is something that we need to make
> > this thing work and to get acceptable performance out of the box. So we
> > can play with it while debugging, but I consider the schedtune slider as
> > the way to tune the system at runtime.
>
> Could the default schedtune value not serve as the out of the box margin?
It can. Let's keep the kernel interfaces in patch #2 for changing the
margin/threshold, and schedtune can call these interfaces.
Regards,
Mike
>
> Regardless I agree that a debug interface is the way to go for now while
> we figure things out.
>
next prev parent reply other threads:[~2016-03-16 22:05 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-14 5:22 [PATCH 0/8] schedutil enhancements Michael Turquette
2016-03-14 5:22 ` [PATCH 1/8] sched/cpufreq: remove cpufreq_trigger_update() Michael Turquette
2016-03-15 21:14 ` Peter Zijlstra
[not found] ` <20160315214545.30639.98727@quark.deferred.io>
2016-03-15 21:49 ` Peter Zijlstra
2016-03-16 8:00 ` Peter Zijlstra
2016-03-14 5:22 ` [PATCH 2/8] sched/fair: add margin to utilization update Michael Turquette
2016-03-15 21:16 ` Peter Zijlstra
[not found] ` <20160315212848.30639.38747@quark.deferred.io>
2016-03-15 21:43 ` Peter Zijlstra
2016-03-16 2:52 ` Steve Muckle
2016-03-16 22:12 ` Michael Turquette
2016-03-14 5:22 ` [PATCH 3/8] sched/cpufreq: new cfs capacity margin helpers Michael Turquette
2016-03-15 21:17 ` Peter Zijlstra
2016-03-14 5:22 ` [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable Michael Turquette
2016-03-15 21:20 ` Peter Zijlstra
[not found] ` <20160315214043.30639.75507@quark.deferred.io>
2016-03-15 21:48 ` Peter Zijlstra
[not found] ` <20160315223701.30639.43127@quark.deferred.io>
2016-03-16 3:36 ` Steve Muckle
2016-03-16 8:05 ` Peter Zijlstra
2016-03-16 10:02 ` Juri Lelli
2016-03-16 17:55 ` Steve Muckle
2016-03-16 22:05 ` Michael Turquette [this message]
2016-03-17 9:40 ` Juri Lelli
2016-03-17 13:55 ` Steve Muckle
2016-03-17 15:53 ` Patrick Bellasi
2016-03-17 17:54 ` Juri Lelli
2016-03-17 18:56 ` Michael Turquette
2016-03-17 22:34 ` Rafael J. Wysocki
2016-03-16 12:45 ` Rafael J. Wysocki
2016-03-16 22:03 ` Michael Turquette
2016-03-14 5:22 ` [PATCH 5/8] sched/cpufreq: pass sched class into cpufreq_update_util Michael Turquette
2016-03-15 21:25 ` Peter Zijlstra
[not found] ` <20160315220609.30639.67271@quark.deferred.io>
2016-03-16 3:55 ` Steve Muckle
2016-03-16 7:41 ` Peter Zijlstra
2016-03-16 8:29 ` Vincent Guittot
2016-03-16 8:53 ` Peter Zijlstra
2016-03-16 9:16 ` Vincent Guittot
2016-03-16 12:39 ` Rafael J. Wysocki
2016-03-16 13:10 ` Peter Zijlstra
2016-03-16 13:23 ` Rafael J. Wysocki
2016-03-16 13:43 ` Peter Zijlstra
2016-03-14 5:22 ` [PATCH 6/8] cpufreq/schedutil: sum per-sched class utilization Michael Turquette
2016-03-15 21:29 ` Peter Zijlstra
[not found] ` <20160315220951.30639.12872@quark.deferred.io>
2016-03-16 7:38 ` Peter Zijlstra
2016-03-16 18:20 ` Steve Muckle
2016-03-16 18:36 ` Peter Zijlstra
2016-03-16 19:12 ` Steve Muckle
2016-03-14 5:22 ` [PATCH 7/8] cpufreq: Frequency invariant scheduler load-tracking support Michael Turquette
2016-03-15 19:13 ` Dietmar Eggemann
2016-03-15 20:19 ` Michael Turquette
2016-03-15 21:32 ` Peter Zijlstra
2016-03-16 18:33 ` Dietmar Eggemann
2016-03-15 21:34 ` Peter Zijlstra
2016-03-14 5:22 ` [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity Michael Turquette
2016-03-15 19:13 ` Dietmar Eggemann
2016-03-15 20:46 ` Michael Turquette
2016-03-16 19:44 ` Dietmar Eggemann
2016-03-16 20:07 ` Peter Zijlstra
2016-03-16 21:32 ` Rafael J. Wysocki
2016-03-15 21:37 ` Peter Zijlstra
[not found] ` <20160315222721.30639.28332@quark.deferred.io>
2016-03-16 7:47 ` Peter Zijlstra
2016-03-16 12:41 ` Peter Zijlstra
2016-03-16 0:08 ` [PATCH 0/8] schedutil enhancements Rafael J. Wysocki
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