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[86.130.134.87]) by smtp.gmail.com with ESMTPSA id e6-20020a5d5946000000b002356c051b9csm2199019wri.66.2022.11.05.06.41.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Nov 2022 06:41:38 -0700 (PDT) Date: Sat, 5 Nov 2022 13:41:36 +0000 From: Qais Yousef To: Joel Fernandes Cc: Vincent Guittot , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org, parth@linux.ibm.com, qais.yousef@arm.com, chris.hyser@oracle.com, patrick.bellasi@matbug.net, David.Laight@aculab.com, pjt@google.com, pavel@ucw.cz, tj@kernel.org, qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com, youssefesmat@chromium.org Subject: Re: [PATCH v7 6/9] sched/fair: Add sched group latency support Message-ID: <20221105134136.zmdbjhw5bf7gr7mv@airbuntu> References: <20221028093403.6673-1-vincent.guittot@linaro.org> <20221028093403.6673-7-vincent.guittot@linaro.org> <20221101192848.pjns3um7dnrwrk5p@airbuntu> <20221103142732.m5ibwkuymvhcdxkn@airbuntu> <20221104112138.hlnwjmw2ls4gswuo@airbuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/22 14:57, Joel Fernandes wrote: > > The current use of latency_nice doesn't need to walk the hierarchy > > because it applies at each scheduling level so the childs > > automatically follow parents' latency. > > Not really, I don't see how that will work that way in the wake up path. The > wake up path (EAS in particular) does not walk through CPU controller group > hierarchy from top level, it only cares about cpuset/affinities and the > "effective" values of tasks. > > So when you wake up a task, how will you retrieve the attribute for 'prefer > idle' in the wakeup path using this patchset? The only way is to aggregate > the CGroup hierarchy information to get a per-task effective value; say using > a min function. > > If you see uclamp_rq_util_with(), that also is using doing uclamp > aggregation similarly. > > So I think Qais is asking about the aggregation function in the EAS wakeup > path. Yes that's what I was trying to say. Thanks for helping to clarify it! Thanks -- Qais Yousef