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From: Peter Zijlstra <peterz@infradead.org>
To: Quentin Perret <quentin.perret@arm.com>
Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org, gregkh@linuxfoundation.org,
	mingo@redhat.com, dietmar.eggemann@arm.com,
	morten.rasmussen@arm.com, chris.redpath@arm.com,
	patrick.bellasi@arm.com, valentin.schneider@arm.com,
	vincent.guittot@linaro.org, thara.gopinath@linaro.org,
	viresh.kumar@linaro.org, tkjos@google.com,
	joel@joelfernandes.org, smuckle@google.com,
	adharmap@codeaurora.org, skannan@codeaurora.org,
	pkondeti@codeaurora.org, juri.lelli@redhat.com,
	edubezval@gmail.com, srinivas.pandruvada@linux.intel.com,
	currojerez@riseup.net, javi.merino@kernel.org
Subject: Re: [PATCH v7 13/14] sched/topology: Make Energy Aware Scheduling depend on schedutil
Date: Thu, 4 Oct 2018 12:50:23 +0200	[thread overview]
Message-ID: <20181004105023.GE19252@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180912091309.7551-14-quentin.perret@arm.com>

On Wed, Sep 12, 2018 at 10:13:08AM +0100, Quentin Perret wrote:
> Energy Aware Scheduling (EAS) is designed with the assumption that
> frequencies of CPUs follow their utilization value. When using a CPUFreq
> governor other than schedutil, the chances of this assumption being true
> are small, if any. When schedutil is being used, EAS' predictions are at
> least consistent with the frequency requests. Although those requests
> have no guarantees to be honored by the hardware, they should at least
> guide DVFS in the right direction and provide some hope in regards to the
> EAS model being accurate.
> 
> To make sure EAS is only used in a sane configuration, create a strong
> dependency on schedutil being used. Since having sugov compiled-in does
> not provide that guarantee, make CPUFreq call a scheduler function on
> on governor changes hence letting it rebuild the scheduling domains,
> check the governors of the online CPUs, and enable/disable EAS
> accordingly.

So this patch disables EAS when we change cpufreq gov. How about we
force select schedutil and disallow changing it when EAS is enabled?

Instead of silently disabling EAS when we frob the governor?

  reply	other threads:[~2018-10-04 10:56 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-12  9:12 [PATCH v7 00/14] Energy Aware Scheduling Quentin Perret
2018-09-12  9:12 ` [PATCH v7 01/14] sched: Relocate arch_scale_cpu_capacity Quentin Perret
2018-09-12  9:12 ` [PATCH v7 02/14] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling Quentin Perret
2018-09-12 14:56   ` Vincent Guittot
2018-09-18 21:33   ` Rafael J. Wysocki
2018-09-27 12:17     ` Quentin Perret
2018-09-28  8:23       ` Rafael J. Wysocki
2018-09-28  8:35         ` Quentin Perret
2018-09-28  8:35           ` Rafael J. Wysocki
2018-09-12  9:12 ` [PATCH v7 03/14] PM: Introduce an Energy Model management framework Quentin Perret
2018-10-02 12:25   ` Peter Zijlstra
2018-10-02 12:54     ` Quentin Perret
2018-10-02 13:50       ` Peter Zijlstra
2018-10-02 12:30   ` Peter Zijlstra
2018-10-02 12:51     ` Quentin Perret
2018-10-02 13:48       ` Peter Zijlstra
2018-10-02 14:05         ` Quentin Perret
2018-10-02 14:29           ` Peter Zijlstra
2018-10-02 14:40             ` Quentin Perret
2018-10-02 19:12               ` Andrea Parri
2018-10-03  7:48                 ` Quentin Perret
2018-09-12  9:12 ` [PATCH v7 04/14] PM / EM: Expose the Energy Model in sysfs Quentin Perret
2018-09-12  9:13 ` [PATCH v7 05/14] sched: Introduce a sched_feat for Energy Aware Scheduling Quentin Perret
2018-10-02 12:34   ` Peter Zijlstra
2018-10-02 13:08     ` Quentin Perret
2018-10-03 16:24       ` Peter Zijlstra
2018-10-04  9:57         ` Quentin Perret
2018-09-12  9:13 ` [PATCH v7 06/14] sched/topology: Reference the Energy Model of CPUs when available Quentin Perret
2018-10-02 12:36   ` Peter Zijlstra
2018-10-02 13:16     ` Quentin Perret
2018-09-12  9:13 ` [PATCH v7 07/14] sched/topology: Lowest CPU asymmetry sched_domain level pointer Quentin Perret
2018-09-12  9:13 ` [PATCH v7 08/14] sched/topology: Disable EAS on inappropriate platforms Quentin Perret
2018-10-03 16:27   ` Peter Zijlstra
2018-10-04  9:10     ` Quentin Perret
2018-10-04  9:38       ` Peter Zijlstra
2018-10-04  9:45         ` Quentin Perret
2018-09-12  9:13 ` [PATCH v7 09/14] sched/fair: Clean-up update_sg_lb_stats parameters Quentin Perret
2018-09-12  9:13 ` [PATCH v7 10/14] sched: Add over-utilization/tipping point indicator Quentin Perret
2018-09-12  9:13 ` [PATCH v7 11/14] sched/fair: Introduce an energy estimation helper function Quentin Perret
2018-10-04  8:34   ` Peter Zijlstra
2018-10-04  9:02     ` Quentin Perret
2018-09-12  9:13 ` [PATCH v7 12/14] sched/fair: Select an energy-efficient CPU on task wake-up Quentin Perret
2018-10-04  9:44   ` Peter Zijlstra
2018-10-04 10:27     ` Quentin Perret
2018-10-04 10:41       ` Peter Zijlstra
2018-10-04 10:55         ` Quentin Perret
2018-10-04 12:18           ` Peter Zijlstra
2018-09-12  9:13 ` [PATCH v7 13/14] sched/topology: Make Energy Aware Scheduling depend on schedutil Quentin Perret
2018-10-04 10:50   ` Peter Zijlstra [this message]
2018-10-04 11:58     ` Quentin Perret
2018-09-12  9:13 ` [PATCH v7 14/14] OPTIONAL: cpufreq: dt: Register an Energy Model Quentin Perret

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