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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id 133sm168385wme.9.2018.12.11.06.15.11 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 11 Dec 2018 06:15:12 -0800 (PST) Date: Tue, 11 Dec 2018 15:15:09 +0100 From: Ingo Molnar To: Quentin Perret Cc: peterz@infradead.org, 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, Peter Zijlstra Subject: Re: [PATCH v10 10/15] sched: Introduce a sysctl for Energy Aware Scheduling Message-ID: <20181211141509.GA32005@gmail.com> References: <20181203095628.11858-1-quentin.perret@arm.com> <20181203095628.11858-11-quentin.perret@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181203095628.11858-11-quentin.perret@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Quentin Perret wrote: > In its current state, Energy Aware Scheduling (EAS) starts automatically > on asymmetric platforms having an Energy Model (EM). However, there are > users who want to have an EM (for thermal management for example), but > don't want EAS with it. Well, then introduce a new Kconfig variant for EAS, if it's super important to allow this to be disabled. Why do we want to disable it - is it not reliable in some circumstances? > In order to let users disable EAS explicitly, introduce a new sysctl > called 'sched_energy_aware'. It is enabled by default so that EAS can > start automatically on platforms where it makes sense. Flipping it to 0 > rebuilds the scheduling domains and disables EAS. Yeah, making this a sysctl ABI is asking for trouble - this really should be a Kconfig or debug space knob, at most. Thanks, Ingo