From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755913AbdLTRol (ORCPT ); Wed, 20 Dec 2017 12:44:41 -0500 Received: from mail-pl0-f68.google.com ([209.85.160.68]:41270 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755453AbdLTRoj (ORCPT ); Wed, 20 Dec 2017 12:44:39 -0500 X-Google-Smtp-Source: ACJfBovPTlNjoJsVKR/zN0kMtIci/Lc7VNtOTiLLvtGKmHAkJp8rEp9INYnzBO11fn5MViFOQjsT0w== Subject: Re: [PATCH RESEND] cpufreq: schedutil: Use idle_calls counter of the remote CPU To: "Rafael J. Wysocki" Cc: Peter Zijlstra , LKML , Srinivas Pandruvada , Len Brown , Viresh Kumar , Ingo Molnar , Juri Lelli , Patrick Bellasi , Chris Redpath , Steve Muckle , Dietmar Eggemann , Vincent Guittot , Morten Ramussen , Frederic Weisbecker , Thomas Gleixner , Saravana Kannan , Vikram Mulukutla , Rohit Jain , Atish Patra , Josef Bacik , Rik van Riel , EAS Dev , linux-pm@vger.kernel.org References: <20171219174712.13806-1-joelaf@google.com> <20171219184811.campbfjw3plynurs@hirez.programming.kicks-ass.net> <1680359.YAEeiLAcPD@aspire.rjw.lan> From: Joel Fernandes Message-ID: Date: Wed, 20 Dec 2017 09:44:35 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <1680359.YAEeiLAcPD@aspire.rjw.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rafael, On 12/20/2017 06:45 AM, Rafael J. Wysocki wrote: > On Tuesday, December 19, 2017 8:32:09 PM CET Joel Fernandes wrote: >> On Tue, Dec 19, 2017 at 10:48 AM, Peter Zijlstra wrote: >>> On Tue, Dec 19, 2017 at 09:47:12AM -0800, Joel Fernandes wrote: >>>> Since the recent remote cpufreq callback work, its possible that a cpufreq >>>> update is triggered from a remote CPU. For single policies however, the current >>>> code uses the local CPU when trying to determine if the remote sg_cpu entered >>>> idle or is busy. This is incorrect. To remedy this, compare with the nohz tick >>>> idle_calls counter of the remote CPU. >>>> >>>> Acked-by: Viresh Kumar >>>> Signed-off-by: Joel Fernandes >>> >>> Acked-by: Peter Zijlstra (Intel) >> >> Sweet! > > OK, so any chance to get a Fixes: tag for the patch? Sure. Please find an inline patch below with all acks and fixes tag. thanks! ---8<--- From: Joel Fernandes Subject: [PATCH] cpufreq: schedutil: Use idle_calls counter of the remote CPU Since the recent remote cpufreq callback work, its possible that a cpufreq update is triggered from a remote CPU. For single policies however, the current code uses the local CPU when trying to determine if the remote sg_cpu entered idle or is busy. This is incorrect. To remedy this, compare with the nohz tick idle_calls counter of the remote CPU. Fixes: 674e75411fc2 ("sched: cpufreq: Allow remote cpufreq callbacks") Acked-by: Viresh Kumar Acked-by: Peter Zijlstra (Intel) Signed-off-by: Joel Fernandes --- include/linux/tick.h | 1 + kernel/sched/cpufreq_schedutil.c | 2 +- kernel/time/tick-sched.c | 13 +++++++++++++ 3 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index f442d1a42025..7cc35921218e 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -119,6 +119,7 @@ extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); extern ktime_t tick_nohz_get_sleep_length(void); extern unsigned long tick_nohz_get_idle_calls(void); +extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); #else /* !CONFIG_NO_HZ_COMMON */ diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 2f52ec0f1539..d6717a3331a1 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -244,7 +244,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util, #ifdef CONFIG_NO_HZ_COMMON static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { - unsigned long idle_calls = tick_nohz_get_idle_calls(); + unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu); bool ret = idle_calls == sg_cpu->saved_idle_calls; sg_cpu->saved_idle_calls = idle_calls; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 99578f06c8d4..77555faf6fbc 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -985,6 +985,19 @@ ktime_t tick_nohz_get_sleep_length(void) return ts->sleep_length; } +/** + * tick_nohz_get_idle_calls_cpu - return the current idle calls counter value + * for a particular CPU. + * + * Called from the schedutil frequency scaling governor in scheduler context. + */ +unsigned long tick_nohz_get_idle_calls_cpu(int cpu) +{ + struct tick_sched *ts = tick_get_tick_sched(cpu); + + return ts->idle_calls; +} + /** * tick_nohz_get_idle_calls - return the current idle calls counter value *