From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752748AbdK3LsR (ORCPT ); Thu, 30 Nov 2017 06:48:17 -0500 Received: from foss.arm.com ([217.140.101.70]:51326 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752684AbdK3LsG (ORCPT ); Thu, 30 Nov 2017 06:48:06 -0500 From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes Subject: [PATCH v3 6/6] cpufreq: schedutil: ignore sugov kthreads Date: Thu, 30 Nov 2017 11:47:23 +0000 Message-Id: <20171130114723.29210-7-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171130114723.29210-1-patrick.bellasi@arm.com> References: <20171130114723.29210-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In system where multiple CPUs shares the same frequency domain a small workload on a CPU can still be subject to 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 policy. 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 Reviewed-by: Dietmar Eggemann 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 --- Changes from v2: - rebased on v4.15-rc1 - moved at the end of the stack since considered more controversial Changes from v1: - move check before policy spinlock (JuriL) Change-Id: I4d749458229b6496dd24a8c357be42cd35a739fd --- kernel/sched/cpufreq_schedutil.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 3eea8884e61b..a93ad5b0c40d 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -270,6 +270,10 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, bool rt_mode; bool busy; + /* Skip updates generated by sugov kthreads */ + if (unlikely(current == sg_policy->thread)) + return; + sugov_set_iowait_boost(sg_cpu, time, flags); sg_cpu->last_update = time; @@ -356,6 +360,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int next_f; bool rt_mode; + /* Skip updates generated by sugov kthreads */ + if (unlikely(current == sg_policy->thread)) + return; + raw_spin_lock(&sg_policy->update_lock); sugov_get_util(&util, &max, sg_cpu->cpu); -- 2.14.1