From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Date: Fri, 28 Jul 2017 11:30:54 +0530 Message-ID: <20170728060054.GU352@vireshk-i7> References: <0f950529a63fb95e87944644c4854be4fcfaea38.1499927699.git.viresh.kumar@linaro.org> <20170721130349.mv7soic62jdnirq5@hirez.programming.kicks-ass.net> <597902DA.8060608@codeaurora.org> <20170727033059.GD352@vireshk-i7> <597A452C.7000303@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <597A452C.7000303@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Saravana Kannan Cc: eas-dev@lists.linaro.org, linux-pm@vger.kernel.org, Peter Zijlstra , Rafael Wysocki , linux-kernel@vger.kernel.org, Ingo Molnar , Srinivas Pandruvada , smuckle.linux@gmail.com, Len Brown List-Id: linux-pm@vger.kernel.org On 27-07-17, 12:55, Saravana Kannan wrote: > Yes. Simplifying isn't always about number of lines of code. It's also about > abstraction. Having generic scheduler code care about HW details doesn't > seem nice. I can argue that even the policy->cpus field is also hardware specific, isn't it ? And we are using that in the schedutil governor anyway. What's wrong with having another field (in a generic way) in the same structure that tells us more about hardware ? And then schedutil isn't really scheduler, but a cpufreq governor. Just like ondemand/conservative, which are also called from the same scheduler path. > It'll literally one simple check (cpu == smp_processor_id()) or (cpu "in" > policy->cpus). > > Also, this is only for drivers that currently support fast switching. How > many of those do you have? Why? Why shouldn't we do that for the other drivers? I think it should be done across everyone. > >The core already has most of the data required and I believe that we > >need to handle it in the governor's code as is handled in this series. > > Clearly, it doesn't. You are just making assumptions about HW. So assuming that any CPU from a policy can change freq on behalf of all the CPUs of the same policy is wrong? That is the basis of how the cpufreq core is designed. -- viresh