Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752222AbdGDRe2 (ORCPT ); Tue, 4 Jul 2017 13:34:28 -0400 Received: from foss.arm.com ([217.140.101.70]:48100 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751982AbdGDReZ (ORCPT ); Tue, 4 Jul 2017 13:34:25 -0400 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 , Juri Lelli , Joel Fernandes , Andres Oportus , Todd Kjos , Morten Rasmussen , Dietmar Eggemann Subject: [PATCH v2 1/6] cpufreq: schedutil: ignore sugov kthreads Date: Tue, 4 Jul 2017 18:34:06 +0100 Message-Id: <1499189651-18797-2-git-send-email-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1499189651-18797-1-git-send-email-patrick.bellasi@arm.com> References: <1499189651-18797-1-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: 1844 Lines: 55 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 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 v1: - move check before policy spinlock (JuriL) --- 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 c982dd0..eaba6d6 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -218,6 +218,10 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, unsigned int next_f; 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; @@ -290,6 +294,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, unsigned long util, max; unsigned int next_f; + /* Skip updates generated by sugov kthreads */ + if (unlikely(current == sg_policy->thread)) + return; + sugov_get_util(&util, &max); raw_spin_lock(&sg_policy->update_lock); -- 2.7.4