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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,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 4C777C433E2 for ; Fri, 11 Sep 2020 23:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11006221E5 for ; Fri, 11 Sep 2020 23:04:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725902AbgIKXEn (ORCPT ); Fri, 11 Sep 2020 19:04:43 -0400 Received: from mga07.intel.com ([134.134.136.100]:19605 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725849AbgIKXEd (ORCPT ); Fri, 11 Sep 2020 19:04:33 -0400 IronPort-SDR: yZo4Cmn3O6DcRnIOiRCEdWj7yovPzufylFKOZ7l55roGWRg6gQ0Brwn93x8Mfwhg3yNVoCSY6s lCgfimZJRBGw== X-IronPort-AV: E=McAfee;i="6000,8403,9741"; a="223055862" X-IronPort-AV: E=Sophos;i="5.76,418,1592895600"; d="scan'208";a="223055862" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2020 16:04:33 -0700 IronPort-SDR: kYLC0J520T7BuTfEgd5jB1ZZWP+1UJHZ+qzj8dmufexyzg3NZNp+gieJvTOB31RH1fa15k2HOM UEJZlURmDvbg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,418,1592895600"; d="scan'208";a="329947624" Received: from cli6-desk1.ccr.corp.intel.com (HELO [10.239.161.135]) ([10.239.161.135]) by fmsmga004.fm.intel.com with ESMTP; 11 Sep 2020 16:04:30 -0700 Subject: Re: [RFC PATCH v1 1/1] sched/fair: select idle cpu from idle cpumask in sched domain To: Qais Yousef , Aubrey Li Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, valentin.schneider@arm.com, tim.c.chen@linux.intel.com, linux-kernel@vger.kernel.org References: <20200910054203.525420-1-aubrey.li@intel.com> <20200910054203.525420-2-aubrey.li@intel.com> <20200911162853.xldy6fvvqph2lahj@e107158-lin.cambridge.arm.com> From: "Li, Aubrey" Message-ID: <3f1571ea-b74c-fc40-2696-39ef3fe8b968@linux.intel.com> Date: Sat, 12 Sep 2020 07:04:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200911162853.xldy6fvvqph2lahj@e107158-lin.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/9/12 0:28, Qais Yousef wrote: > On 09/10/20 13:42, Aubrey Li wrote: >> Added idle cpumask to track idle cpus in sched domain. When a CPU >> enters idle, its corresponding bit in the idle cpumask will be set, >> and when the CPU exits idle, its bit will be cleared. >> >> When a task wakes up to select an idle cpu, scanning idle cpumask >> has low cost than scanning all the cpus in last level cache domain, >> especially when the system is heavily loaded. >> >> Signed-off-by: Aubrey Li >> --- >> include/linux/sched/topology.h | 13 +++++++++++++ >> kernel/sched/fair.c | 4 +++- >> kernel/sched/topology.c | 2 +- >> 3 files changed, 17 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h >> index fb11091129b3..43a641d26154 100644 >> --- a/include/linux/sched/topology.h >> +++ b/include/linux/sched/topology.h >> @@ -65,8 +65,21 @@ struct sched_domain_shared { >> atomic_t ref; >> atomic_t nr_busy_cpus; >> int has_idle_cores; >> + /* >> + * Span of all idle CPUs in this domain. >> + * >> + * NOTE: this field is variable length. (Allocated dynamically >> + * by attaching extra space to the end of the structure, >> + * depending on how many CPUs the kernel has booted up with) >> + */ >> + unsigned long idle_cpus_span[]; > > Can't you use cpumask_var_t and zalloc_cpumask_var() instead? I can use the existing free code. Do we have a problem of this? > > The patch looks useful. Did it help you with any particular workload? It'd be > good to expand on that in the commit message. > Odd, that included in patch v1 0/1, did you receive it? Thanks, -Aubrey