From patchwork Wed Jan 15 04:48:51 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Shi X-Patchwork-Id: 23206 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-vb0-f72.google.com (mail-vb0-f72.google.com [209.85.212.72]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 8DAC0202FA for ; Wed, 15 Jan 2014 04:49:10 +0000 (UTC) Received: by mail-vb0-f72.google.com with SMTP id x8sf880721vbf.11 for ; Tue, 14 Jan 2014 20:49:09 -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=lKlt7w9CFJgm6gQTOBbJLgr4HUk8ffTnaZqp4mMp7jc=; b=IeebchF8wQ3VsCpEeEM/optMepJTegGDjvucUApt3foT1t/zSe30YBG7eURI2bnaxV KJzdQnn3yAdTATkRJknIYCeYAA/zHrXm/HAItLJywreOVzHATDVIAvOS+Rsfsvx7TVy5 Qy30FthFgurvmS8Nt+XlptZPUh3hDAoIzLzG1NrwKu2ji3H9AEUxh8pjmO4NK8GEhREc R04vu2KA9/VpWpGCunlDMGzSDt1Wlb7EgZditPDBYXs7VSIIRvRe/Cm+Giz6OppACd6v VEbauu6UIZPrIdaxwiLwmy7YFXmHSzal9NQ8yOmg819jafPrgkNM0++Zwav0W311o9zF ebAA== X-Gm-Message-State: ALoCoQkT60D0REDnWZ07fBN4X/exx0A59qS8k6orRbJz9GfUHH4jJsQIsLF+AksG4pNFFk6mCHua X-Received: by 10.52.229.41 with SMTP id sn9mr37908vdc.6.1389761349525; Tue, 14 Jan 2014 20:49:09 -0800 (PST) X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.108.65 with SMTP id hi1ls483482qeb.24.gmail; Tue, 14 Jan 2014 20:49:09 -0800 (PST) X-Received: by 10.221.37.200 with SMTP id tf8mr42694vcb.54.1389761349447; Tue, 14 Jan 2014 20:49:09 -0800 (PST) Received: from mail-vb0-f51.google.com (mail-vb0-f51.google.com [209.85.212.51]) by mx.google.com with ESMTPS id yv5si1098632veb.26.2014.01.14.20.49.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 20:49:09 -0800 (PST) Received-SPF: neutral (google.com: 209.85.212.51 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.212.51; Received: by mail-vb0-f51.google.com with SMTP id 11so211660vbe.24 for ; Tue, 14 Jan 2014 20:49:09 -0800 (PST) X-Received: by 10.58.208.130 with SMTP id me2mr185843vec.13.1389761349342; Tue, 14 Jan 2014 20:49:09 -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 ey3csp248218ved; Tue, 14 Jan 2014 20:49:08 -0800 (PST) X-Received: by 10.66.139.169 with SMTP id qz9mr184028pab.16.1389761348413; Tue, 14 Jan 2014 20:49:08 -0800 (PST) Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id qx4si2518069pbc.75.2014.01.14.20.49.07; Tue, 14 Jan 2014 20:49:07 -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 S1751600AbaAOEtB (ORCPT + 26 others); Tue, 14 Jan 2014 23:49:01 -0500 Received: from mail-pa0-f50.google.com ([209.85.220.50]:34247 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751253AbaAOEs7 (ORCPT ); Tue, 14 Jan 2014 23:48:59 -0500 Received: by mail-pa0-f50.google.com with SMTP id kp14so616796pab.37 for ; Tue, 14 Jan 2014 20:48:58 -0800 (PST) X-Received: by 10.68.111.98 with SMTP id ih2mr13922pbb.73.1389761338803; Tue, 14 Jan 2014 20:48:58 -0800 (PST) Received: from [10.0.0.100] ([162.243.130.63]) by mx.google.com with ESMTPSA id qp15sm5020621pbb.2.2014.01.14.20.48.53 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 20:48:57 -0800 (PST) Message-ID: <52D61333.8060705@linaro.org> Date: Wed, 15 Jan 2014 12:48:51 +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> In-Reply-To: <52D60F11.3070005@linux.vnet.ibm.com> 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: 209.85.212.51 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 12:31 PM, Michael wang wrote: > Hi, Alex > > On 01/15/2014 12:07 PM, Alex Shi wrote: > [snip] } >> +#ifdef CONFIG_NO_HZ_COMMON >> + /* >> + * Coarsely to get the latest idle cpu for shorter latency and >> + * possible power benefit. >> + */ >> + if (!min_load) { here should be !load. >> + struct tick_sched *ts = &per_cpu(tick_cpu_sched, i); >> + >> + s64 latest_wake = 0; > > I guess we missed some code for latest_wake here? Yes, thanks for reminder! so updated patch: ==== >From c3a88e73fed3da96549b5a922076e996832685f8 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 | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c7395d9..73a2a07 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4167,6 +4167,31 @@ 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); + + s64 latest_wake = 0; + /* 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;