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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 A69D4C433B4 for ; Tue, 18 May 2021 14:27:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88B1F6109F for ; Tue, 18 May 2021 14:27:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232770AbhERO3P (ORCPT ); Tue, 18 May 2021 10:29:15 -0400 Received: from foss.arm.com ([217.140.110.172]:53410 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231792AbhERO3N (ORCPT ); Tue, 18 May 2021 10:29:13 -0400 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 90DA0ED1; Tue, 18 May 2021 07:27:55 -0700 (PDT) Received: from e120325.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1425A3F73B; Tue, 18 May 2021 07:27:53 -0700 (PDT) Date: Tue, 18 May 2021 15:27:46 +0100 From: Beata Michalska To: Vincent Guittot Cc: linux-kernel , Peter Zijlstra , Ingo Molnar , Juri Lelli , Valentin Schneider , Dietmar Eggemann , "corbet@lwn.net" , Randy Dunlap , Linux Doc Mailing List Subject: Re: [PATCH v4 1/3] sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag Message-ID: <20210518142746.GA3993@e120325.cambridge.arm.com> References: <1621239831-5870-1-git-send-email-beata.michalska@arm.com> <1621239831-5870-2-git-send-email-beata.michalska@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, May 18, 2021 at 03:39:27PM +0200, Vincent Guittot wrote: > On Mon, 17 May 2021 at 10:24, Beata Michalska wrote: > > > > Introducing new, complementary to SD_ASYM_CPUCAPACITY, sched_domain > > topology flag, to distinguish between shed_domains where any CPU > > capacity asymmetry is detected (SD_ASYM_CPUCAPACITY) and ones where > > a full range of CPU capacities is visible to all domain members > > (SD_ASYM_CPUCAPACITY_FULL). > > I'm not sure about what you want to detect: > > Is it a sched_domain level with a full range of cpu capacity, i.e. > with at least 1 min capacity and 1 max capacity ? > or do you want to get at least 1 cpu of each capacity ? That would be at least one CPU of each available capacity within given domain, so full -set- of available capacities within a domain. --- BR B. > > > > > > With the distinction between full and partial CPU capacity asymmetry, > > brought in by the newly introduced flag, the scope of the original > > SD_ASYM_CPUCAPACITY flag gets shifted, still maintaining the existing > > behaviour when one is detected on a given sched domain, allowing > > misfit migrations within sched domains that do not observe full range > > of CPU capacities but still do have members with different capacity > > values. It loses though it's meaning when it comes to the lowest CPU > > asymmetry sched_domain level per-cpu pointer, which is to be now > > denoted by SD_ASYM_CPUCAPACITY_FULL flag. > > > > Signed-off-by: Beata Michalska > > Reviewed-by: Valentin Schneider > > --- > > include/linux/sched/sd_flags.h | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/include/linux/sched/sd_flags.h b/include/linux/sched/sd_flags.h > > index 34b21e9..57bde66 100644 > > --- a/include/linux/sched/sd_flags.h > > +++ b/include/linux/sched/sd_flags.h > > @@ -91,6 +91,16 @@ SD_FLAG(SD_WAKE_AFFINE, SDF_SHARED_CHILD) > > SD_FLAG(SD_ASYM_CPUCAPACITY, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > > > > /* > > + * Domain members have different CPU capacities spanning all unique CPU > > + * capacity values. > > + * > > + * SHARED_PARENT: Set from the topmost domain down to the first domain where > > + * all available CPU capacities are visible > > + * NEEDS_GROUPS: Per-CPU capacity is asymmetric between groups. > > + */ > > +SD_FLAG(SD_ASYM_CPUCAPACITY_FULL, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) > > + > > +/* > > * Domain members share CPU capacity (i.e. SMT) > > * > > * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share > > -- > > 2.7.4 > >