From patchwork Wed Jan 15 05:06:56 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Shi X-Patchwork-Id: 23208 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-ie0-f197.google.com (mail-ie0-f197.google.com [209.85.223.197]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id D7CA8202FA for ; Wed, 15 Jan 2014 05:07:20 +0000 (UTC) Received: by mail-ie0-f197.google.com with SMTP id e14sf3858591iej.4 for ; Tue, 14 Jan 2014 21:07:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:delivered-to:message-id:date:from:user-agent :mime-version:to:cc:subject:references:in-reply-to:sender:precedence :list-id:x-original-sender:x-original-authentication-results :mailing-list:list-post:list-help:list-archive:list-unsubscribe :content-type:content-transfer-encoding; bh=BVWUthOmVqbI+q4UWZ9e1F77YpTAzX6TduCo2hGWwhQ=; b=l4DpHTaJIAgO2r9DPujXfuUcyewzadq2bBtB0WKWxp8BDMVxgra3q+aWaKhaUrnBYP iIZxk+zlWOJ+qJyYheAqJkAMlSuGHIlyemJB0U2S22wZVdICdCZB7NdaRvX8dXjTQrTm jVUG6OUIhUgl7aoHAqt6KTdNyPMw50kZHX6CCGTe/Y7IieWTRSva1Zh/uhGo4/fTDOkq 87rMrhGiwLMRIU5ES1knV4tCG10iMp8e2zRcOT0qfjOSEF6hS/rHoe6fty6LNNh+ttbO aOF0cpo1vR6WCUuWPkw/snAa92UhQGj50bCW1efxBZYZvxjw5xPXN1/7xr85LBTOdLoe 4mTQ== X-Gm-Message-State: ALoCoQkCfDHIdD+W9K8CTyBU3ZtoMzx88UZp9qPyoRA3KbKiK6X7cr2rORgAFeYIU4OeXuu3e0BE X-Received: by 10.43.78.135 with SMTP id zm7mr70261icb.27.1389762439931; Tue, 14 Jan 2014 21:07:19 -0800 (PST) X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.88.68 with SMTP id be4ls455955qeb.46.gmail; Tue, 14 Jan 2014 21:07:19 -0800 (PST) X-Received: by 10.220.133.80 with SMTP id e16mr52941vct.13.1389762439828; Tue, 14 Jan 2014 21:07:19 -0800 (PST) Received: from mail-vc0-f176.google.com (mail-vc0-f176.google.com [209.85.220.176]) by mx.google.com with ESMTPS id be7si1106227vcb.110.2014.01.14.21.07.19 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 21:07:19 -0800 (PST) Received-SPF: neutral (google.com: 209.85.220.176 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.220.176; Received: by mail-vc0-f176.google.com with SMTP id la4so217221vcb.7 for ; Tue, 14 Jan 2014 21:07:19 -0800 (PST) X-Received: by 10.220.206.198 with SMTP id fv6mr64929vcb.70.1389762439723; Tue, 14 Jan 2014 21:07:19 -0800 (PST) X-Forwarded-To: patchwork-forward@linaro.org X-Forwarded-For: patch@linaro.org patchwork-forward@linaro.org Delivered-To: patch@linaro.org Received: by 10.59.13.131 with SMTP id ey3csp248938ved; Tue, 14 Jan 2014 21:07:19 -0800 (PST) X-Received: by 10.68.162.131 with SMTP id ya3mr197110pbb.102.1389762438588; Tue, 14 Jan 2014 21:07:18 -0800 (PST) Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id s4si2551523pbg.93.2014.01.14.21.07.17; Tue, 14 Jan 2014 21:07:17 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751584AbaAOFHJ (ORCPT + 26 others); Wed, 15 Jan 2014 00:07:09 -0500 Received: from mail-pd0-f169.google.com ([209.85.192.169]:44717 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994AbaAOFHG (ORCPT ); Wed, 15 Jan 2014 00:07:06 -0500 Received: by mail-pd0-f169.google.com with SMTP id v10so612888pde.14 for ; Tue, 14 Jan 2014 21:07:05 -0800 (PST) X-Received: by 10.68.236.35 with SMTP id ur3mr47984pbc.137.1389762425179; Tue, 14 Jan 2014 21:07:05 -0800 (PST) Received: from [10.0.0.100] ([162.243.130.63]) by mx.google.com with ESMTPSA id os1sm6687521pac.20.2014.01.14.21.06.59 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 21:07:04 -0800 (PST) Message-ID: <52D61770.1090100@linaro.org> Date: Wed, 15 Jan 2014 13:06:56 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Michael wang , mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, daniel.lezcano@linaro.org, vincent.guittot@linaro.org, morten.rasmussen@arm.com CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, fengguang.wu@intel.com, linaro-kernel@lists.linaro.org Subject: Re: [RFC PATCH] sched: find the latest idle cpu References: <1389758879-19951-1-git-send-email-alex.shi@linaro.org> <52D60F11.3070005@linux.vnet.ibm.com> <52D61333.8060705@linaro.org> <52D61448.3070108@linaro.org> In-Reply-To: <52D61448.3070108@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: alex.shi@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.220.176 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , On 01/15/2014 12:53 PM, Alex Shi wrote: >>> >> I guess we missed some code for latest_wake here? >> > >> > Yes, thanks for reminder! >> > >> > so updated patch: >> > > ops, still incorrect. re-updated: update to wrong file. re-re-update. :( === >From b75e43bb77df14e2209532c1e5c48e0e03afa414 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Tue, 14 Jan 2014 23:07:42 +0800 Subject: [PATCH] sched: find the latest idle cpu Currently we just try to find least load cpu. If some cpus idled, we just pick the first cpu in cpu mask. In fact we can get the interrupted idle cpu or the latest idled cpu, then we may get the benefit from both latency and power. The selected cpu maybe not the best, since other cpu may be interrupted during our selecting. But be captious costs too much. Signed-off-by: Alex Shi --- kernel/sched/fair.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c7395d9..f82ca3d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4159,6 +4159,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) int idlest = -1; int i; +#ifdef CONFIG_NO_HZ_COMMON + s64 latest_wake = 0; +#endif + /* Traverse only the allowed CPUs */ for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { load = weighted_cpuload(i); @@ -4167,6 +4171,30 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) min_load = load; idlest = i; } +#ifdef CONFIG_NO_HZ_COMMON + /* + * Coarsely to get the latest idle cpu for shorter latency and + * possible power benefit. + */ + if (!load) { + struct tick_sched *ts = &per_cpu(tick_cpu_sched, i); + + /* idle cpu doing irq */ + if (ts->inidle && !ts->idle_active) + idlest = i; + /* the cpu resched */ + else if (!ts->inidle) + idlest = i; + /* find latest idle cpu */ + else { + s64 temp = ktime_to_us(ts->idle_entrytime); + if (temp > latest_wake) { + latest_wake = temp; + idlest = i; + } + } + } +#endif } return idlest;