From mboxrd@z Thu Jan 1 00:00:00 1970 From: Saravana Kannan Subject: Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Date: Wed, 26 Jul 2017 14:00:10 -0700 Message-ID: <597902DA.8060608@codeaurora.org> References: <0f950529a63fb95e87944644c4854be4fcfaea38.1499927699.git.viresh.kumar@linaro.org> <20170721130349.mv7soic62jdnirq5@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:59646 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbdGZVAM (ORCPT ); Wed, 26 Jul 2017 17:00:12 -0400 In-Reply-To: <20170721130349.mv7soic62jdnirq5@hirez.programming.kicks-ass.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Peter Zijlstra Cc: Viresh Kumar , linux-pm@vger.kernel.org, Rafael Wysocki , linux-kernel@vger.kernel.org, Ingo Molnar , Srinivas Pandruvada , eas-dev@lists.linaro.org, smuckle.linux@gmail.com, Len Brown On 07/21/2017 06:03 AM, Peter Zijlstra wrote: > On Thu, Jul 13, 2017 at 12:14:37PM +0530, Viresh Kumar wrote: >> diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c >> index 47e24b5384b3..606b1a37a1af 100644 >> --- a/drivers/cpufreq/cpufreq_governor.c >> +++ b/drivers/cpufreq/cpufreq_governor.c >> @@ -275,6 +275,10 @@ static void dbs_update_util_handler(struct update_util_data *data, u64 time, >> struct policy_dbs_info *policy_dbs = cdbs->policy_dbs; >> u64 delta_ns, lst; >> >> + /* Don't allow remote callbacks */ >> + if (smp_processor_id() != data->cpu) >> + return; >> + > > The alternative is using some of that policy_dbs->policy->*cpus crud I > suppose, because: No, the alternative is to pass it on to the CPU freq driver and let it decide what it wants to do. That's the whole point if having a CPU freq driver -- so that the generic code doesn't need to care about HW specific details. Which is the point I was making in an earlier email to Viresh's patch -- we shouldn't be doing any CPU check for the call backs at the scheduler or ever governor level. That would simplify this whole thing by deleting a bunch of code. And having much simpler checks in those drivers that actually have to deal with their HW specific details. -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project