From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90645C47435 for ; Tue, 8 Dec 2020 09:58:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CF4423A84 for ; Tue, 8 Dec 2020 09:58:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728888AbgLHJ6a (ORCPT ); Tue, 8 Dec 2020 04:58:30 -0500 Received: from foss.arm.com ([217.140.110.172]:46620 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727132AbgLHJ63 (ORCPT ); Tue, 8 Dec 2020 04:58:29 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E8B371FB; Tue, 8 Dec 2020 01:57:43 -0800 (PST) Received: from [192.168.178.2] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 768F23F68F; Tue, 8 Dec 2020 01:57:41 -0800 (PST) Subject: Re: [PATCH 2/4] sched/fair: Do not replace recent_used_cpu with the new target To: Mel Gorman , LKML Cc: Aubrey Li , Barry Song , Ingo Molnar , Peter Ziljstra , Juri Lelli , Vincent Guittot , Valentin Schneider , Linux-ARM References: <20201207091516.24683-1-mgorman@techsingularity.net> <20201207091516.24683-3-mgorman@techsingularity.net> From: Dietmar Eggemann Message-ID: <842ef1db-49d1-7d05-997b-1562383cdd28@arm.com> Date: Tue, 8 Dec 2020 10:57:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201207091516.24683-3-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/12/2020 10:15, Mel Gorman wrote: > After select_idle_sibling, p->recent_used_cpu is set to the > new target. However on the next wakeup, prev will be the same as I'm confused here. Isn't current->recent_used_cpu set to 'cpu = smp_processor_id()' after sis()? Looking at v5.10-rc6. [...] > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 23934dbac635..01b38fc17bca 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6274,6 +6274,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > > /* Check a recently used CPU as a potential idle candidate: */ > recent_used_cpu = p->recent_used_cpu; > + p->recent_used_cpu = prev; > if (recent_used_cpu != prev && > recent_used_cpu != target && > cpus_share_cache(recent_used_cpu, target) && p->recent_used_cpu is already set to prev in this if condition. asym_fits_capacity(task_util, recent_used_cpu)) { /* * Replace recent_used_cpu with prev as it is a potential * candidate for the next wake: */ p->recent_used_cpu = prev; return recent_used_cpu; > @@ -6765,9 +6766,6 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) > } else if (wake_flags & WF_TTWU) { /* XXX always ? */ > /* Fast path */ > new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); > - > - if (want_affine) > - current->recent_used_cpu = cpu; > } > rcu_read_unlock(); From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C66BCC4361B for ; Tue, 8 Dec 2020 09:59:00 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 65F1D217A0 for ; Tue, 8 Dec 2020 09:59:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 65F1D217A0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NgLPq0fh6zuHDCSfTtZXCEfNfJ1Iy+ffhZ5PbaT/Hic=; b=RRzfgrqRPqOYwf4ZA1b6gvUy0 PrAiNKM86WBvc29GNNjGthgG1N/sZOQudqYG/PrnR9N3ezDg/i0ABtBhpZzU9JRBVBKPTs40Q1sD/ zXIwWTnXlArpHhUuS57BVBEcFvgfXsJYrV9nCPhr4Xzn+i3vMx+u36phqczwG9pf2Ovz3xIoxO1SM 8O0QmjTuUFoKotUAr7oDOQEmarq1JIb35/HErJG/8iDMnFjoJzErX6klsmxl4VwG3Hvx/k8aW3obN f+Km4iSVfTFz/vWBC3BuLEKDYeSqJAyvj/zzbRhe/X9Vg3g8WPhsY4ejT4T6QHLkZDGYnwm9T/+++ wQu053Hew==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmZkj-0005cq-P5; Tue, 08 Dec 2020 09:57:49 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmZkh-0005bT-6j for linux-arm-kernel@lists.infradead.org; Tue, 08 Dec 2020 09:57:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E8B371FB; Tue, 8 Dec 2020 01:57:43 -0800 (PST) Received: from [192.168.178.2] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 768F23F68F; Tue, 8 Dec 2020 01:57:41 -0800 (PST) Subject: Re: [PATCH 2/4] sched/fair: Do not replace recent_used_cpu with the new target To: Mel Gorman , LKML References: <20201207091516.24683-1-mgorman@techsingularity.net> <20201207091516.24683-3-mgorman@techsingularity.net> From: Dietmar Eggemann Message-ID: <842ef1db-49d1-7d05-997b-1562383cdd28@arm.com> Date: Tue, 8 Dec 2020 10:57:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201207091516.24683-3-mgorman@techsingularity.net> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201208_045747_319908_E416B791 X-CRM114-Status: GOOD ( 17.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Barry Song , Juri Lelli , Vincent Guittot , Peter Ziljstra , Aubrey Li , Ingo Molnar , Valentin Schneider , Linux-ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/12/2020 10:15, Mel Gorman wrote: > After select_idle_sibling, p->recent_used_cpu is set to the > new target. However on the next wakeup, prev will be the same as I'm confused here. Isn't current->recent_used_cpu set to 'cpu = smp_processor_id()' after sis()? Looking at v5.10-rc6. [...] > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 23934dbac635..01b38fc17bca 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6274,6 +6274,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > > /* Check a recently used CPU as a potential idle candidate: */ > recent_used_cpu = p->recent_used_cpu; > + p->recent_used_cpu = prev; > if (recent_used_cpu != prev && > recent_used_cpu != target && > cpus_share_cache(recent_used_cpu, target) && p->recent_used_cpu is already set to prev in this if condition. asym_fits_capacity(task_util, recent_used_cpu)) { /* * Replace recent_used_cpu with prev as it is a potential * candidate for the next wake: */ p->recent_used_cpu = prev; return recent_used_cpu; > @@ -6765,9 +6766,6 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags) > } else if (wake_flags & WF_TTWU) { /* XXX always ? */ > /* Fast path */ > new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); > - > - if (want_affine) > - current->recent_used_cpu = cpu; > } > rcu_read_unlock(); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel