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[35.187.36.109]) by smtp.gmail.com with ESMTPSA id m16-20020a05600c3b1000b0039c673952bfsm17156749wms.6.2022.06.14.04.47.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jun 2022 04:47:07 -0700 (PDT) Date: Tue, 14 Jun 2022 12:47:03 +0100 From: Vincent Donnefort To: Lukasz Luba Cc: linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, qperret@google.com, tao.zhou@linux.dev, kernel-team@android.com, peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org Subject: Re: [PATCH v10 0/7] feec() energy margin removal Message-ID: References: <20220607123254.565579-1-vdonnefort@google.com> <6099583c-c986-e1f3-1eee-33b504286757@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6099583c-c986-e1f3-1eee-33b504286757@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 09, 2022 at 01:53:22PM +0100, Lukasz Luba wrote: > Hi Vincent, > > On 6/7/22 13:32, Vincent Donnefort wrote: > > Hi, > > > > Here's a new version of the patch-set to get rid of the energy margin in > > feec(). Many thanks to all for the insightful comments I got. > > > > find_energy_efficient() (feec()) will migrate a task to save energy only if > > it saves at least 6% of the total energy consumed by the system. This > > conservative approach is a problem on a system where a lot of small tasks > > create a huge load on the overall: very few of them will be allowed to > > migrate to a smaller CPU, wasting a lot of energy. Instead of trying to > > determine yet another margin, let's try to remove it. > > > > The first elements of this patch-set are various fixes and improvement that > > stabilizes task_util and ensures energy comparison fairness across all CPUs > > of the topology. Only once those fixed, we can completely remove the margin > > and let feec() aggressively place task and save energy. > > > > I've run this patch set on pixel6 (android-mainline) and gathered energy > values from the meter during the PCmark 3.0. > > It looks good, with these patches we have ~10% lower energy usage and > only ~3% lower score. > > There are no other issues, everything works fine. Feel free to add: > > Tested-by: Lukasz Luba > > to the whole patch set. > > Regards, > Lukasz Thanks a lot Lukasz!