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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 A93E5C3A5A5 for ; Thu, 5 Sep 2019 10:20:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7DEFD20693 for ; Thu, 5 Sep 2019 10:20:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732373AbfIEKUC (ORCPT ); Thu, 5 Sep 2019 06:20:02 -0400 Received: from foss.arm.com ([217.140.110.172]:41194 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbfIEKUC (ORCPT ); Thu, 5 Sep 2019 06:20:02 -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 C02601576; Thu, 5 Sep 2019 03:20:01 -0700 (PDT) Received: from e110439-lin (e110439-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 16F353F718; Thu, 5 Sep 2019 03:19:59 -0700 (PDT) References: <20190830174944.21741-1-subhra.mazumdar@oracle.com> <20190830174944.21741-5-subhra.mazumdar@oracle.com> User-agent: mu4e 1.3.3; emacs 26.2 From: Patrick Bellasi To: subhra mazumdar Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, tglx@linutronix.de, steven.sistare@oracle.com, dhaval.giani@oracle.com, daniel.lezcano@linaro.org, vincent.guittot@linaro.org, viresh.kumar@linaro.org, tim.c.chen@linux.intel.com, mgorman@techsingularity.net, parth@linux.ibm.com Subject: Re: [RFC PATCH 4/9] sched: SIS_CORE to disable idle core search In-reply-to: <20190830174944.21741-5-subhra.mazumdar@oracle.com> Date: Thu, 05 Sep 2019 11:19:57 +0100 Message-ID: <87lfv32gfm.fsf@arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 30, 2019 at 18:49:39 +0100, subhra mazumdar wrote... > Use SIS_CORE to disable idle core search. For some workloads > select_idle_core becomes a scalability bottleneck, removing it improves > throughput. Also there are workloads where disabling it can hurt latency, > so need to have an option. > > Signed-off-by: subhra mazumdar > --- > kernel/sched/fair.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index c31082d..23ec9c6 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6268,9 +6268,11 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > if (!sd) > return target; > > - i = select_idle_core(p, sd, target); > - if ((unsigned)i < nr_cpumask_bits) > - return i; > + if (sched_feat(SIS_CORE)) { > + i = select_idle_core(p, sd, target); > + if ((unsigned)i < nr_cpumask_bits) > + return i; > + } > > i = select_idle_cpu(p, sd, target); > if ((unsigned)i < nr_cpumask_bits) This looks like should be squashed with the previous one, or whatever code you'll add to define when this "biasing" is to be used or not. Best, Patrick -- #include Patrick Bellasi