From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753732AbcICA7Z (ORCPT ); Fri, 2 Sep 2016 20:59:25 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:59803 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752745AbcICA7P (ORCPT ); Fri, 2 Sep 2016 20:59:15 -0400 From: "Rafael J. Wysocki" To: Linux PM list Cc: Linux Kernel Mailing List , Srinivas Pandruvada , Peter Zijlstra , Viresh Kumar , Ingo Molnar , Vincent Guittot , Morten Rasmussen , Juri Lelli , Dietmar Eggemann , Steve Muckle , Doug Smythies Subject: [RFC/RFT][PATCH 1/4] cpufreq / sched: SCHED_CPUFREQ_IOWAIT flag to indicate iowait condition Date: Sat, 03 Sep 2016 02:58:16 +0200 Message-ID: <3377615.dXdeTBrlhd@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.8.0-rc2+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <2730042.XLMy9dAKI1@vostro.rjw.lan> References: <2730042.XLMy9dAKI1@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Testing indicates that it is possible to improve performace significantly without increasing energy consumption too much by teaching cpufreq governors to bump up the CPU performance level if the in_iowait flag is set for the task in enqueue_task_fair(). For this purpose, define a new cpufreq_update_util() flag SCHED_CPUFREQ_IOWAIT and modify enqueue_task_fair() to pass that flag to cpufreq_update_util() in the in_iowait case. That generally requires cpufreq_update_util() to be called directly from there, because update_load_avg() may not be invoked in that case. Signed-off-by: Rafael J. Wysocki --- include/linux/sched.h | 1 + kernel/sched/fair.c | 8 ++++++++ 2 files changed, 9 insertions(+) Index: linux-pm/kernel/sched/fair.c =================================================================== --- linux-pm.orig/kernel/sched/fair.c +++ linux-pm/kernel/sched/fair.c @@ -4500,6 +4500,14 @@ enqueue_task_fair(struct rq *rq, struct struct cfs_rq *cfs_rq; struct sched_entity *se = &p->se; + /* + * If in_iowait is set, the code below may not trigger any cpufreq + * utilization updates, so do it here explicitly with the IOWAIT flag + * passed. + */ + if (p->in_iowait) + cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IOWAIT); + for_each_sched_entity(se) { if (se->on_rq) break; Index: linux-pm/include/linux/sched.h =================================================================== --- linux-pm.orig/include/linux/sched.h +++ linux-pm/include/linux/sched.h @@ -3471,6 +3471,7 @@ static inline unsigned long rlimit_max(u #define SCHED_CPUFREQ_RT (1U << 0) #define SCHED_CPUFREQ_DL (1U << 1) +#define SCHED_CPUFREQ_IOWAIT (1U << 2) #define SCHED_CPUFREQ_RT_DL (SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL)