Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753982AbdCBPtP (ORCPT ); Thu, 2 Mar 2017 10:49:15 -0500 Received: from foss.arm.com ([217.140.101.70]:32890 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752746AbdCBPqj (ORCPT ); Thu, 2 Mar 2017 10:46:39 -0500 From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: Patrick Bellasi , Viresh Kumar , Steven Rostedt , Vincent Guittot , John Stultz , Juri Lelli , Todd Kjos , Tim Murray , Andres Oportus , Joel Fernandes , Morten Rasmussen , Dietmar Eggemann , Chris Redpath , Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" Subject: [PATCH 2/6] cpufreq: schedutil: ignore the sugov kthread for frequencies selections Date: Thu, 2 Mar 2017 15:45:03 +0000 Message-Id: <1488469507-32463-3-git-send-email-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488469507-32463-1-git-send-email-patrick.bellasi@arm.com> References: <1488469507-32463-1-git-send-email-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1766 Lines: 49 In system where multiple CPUs shares the same frequency domain a small workload on a CPU can still be subject frequency spikes, generated by the activation of the sugov's kthread. Since the sugov kthread is a special RT task, which goal is just that to activate a frequency transition, it does not make sense for it to bias the schedutil's frequency selection. This patch exploits the information related to the current task to silently ignore cpufreq_update_this_cpu() calls, coming from the RT scheduler, while the sugov kthread is running. Signed-off-by: Patrick Bellasi Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- kernel/sched/cpufreq_schedutil.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 084a98b..a3fe5e4 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -274,6 +274,8 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, { struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util); struct sugov_policy *sg_policy = sg_cpu->sg_policy; + unsigned int cpu = smp_processor_id(); + struct task_struct *curr = cpu_curr(cpu); unsigned long util, max; unsigned int next_f; @@ -287,6 +289,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, goto done; } + /* Skip updates generated by sugov kthreads */ + if (curr == sg_policy->thread) + goto done; + sg_cpu->util = util; sg_cpu->max = max; sg_cpu->flags = flags; -- 2.7.4