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=-8.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 6B180C8300A for ; Thu, 30 Apr 2020 10:55:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4541E20784 for ; Thu, 30 Apr 2020 10:55:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="QQHZAy1f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726842AbgD3Kz0 (ORCPT ); Thu, 30 Apr 2020 06:55:26 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:50542 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726413AbgD3Kz0 (ORCPT ); Thu, 30 Apr 2020 06:55:26 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1588244125; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=OsZ/pNJ65qyQXurGQU11CbmokKkvoyDjj3d8TxgSEco=; b=QQHZAy1f/KkYSwBe8DVAgr+XBDgQt8MGRPzx4m0PmK13VFhP5A01uMeAIzLPbUEothlqSHPm wFsUcC5PxLPlLBHCvYJnBQZ5A/JxicgU3vIOFu2e/RB5BgrRLn4FlFLCDQb6aB+hsFOrbus5 0WzZ/sv0Ixxn2MZbdU/l5RHGBlo= X-Mailgun-Sending-Ip: 104.130.122.26 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5eaaae9d.7f090a701ae8-smtp-out-n05; Thu, 30 Apr 2020 10:55:25 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 96644C4478F; Thu, 30 Apr 2020 10:55:23 +0000 (UTC) Received: from codeaurora.org (blr-c-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: pkondeti) by smtp.codeaurora.org (Postfix) with ESMTPSA id 269BEC433CB; Thu, 30 Apr 2020 10:55:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 269BEC433CB Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=pkondeti@codeaurora.org Date: Thu, 30 Apr 2020 16:25:15 +0530 From: Pavan Kondeti To: Dietmar Eggemann Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Luca Abeni , Daniel Bristot de Oliveira , Wei Wang , Quentin Perret , Alessio Balsini , Patrick Bellasi , Morten Rasmussen , Valentin Schneider , Qais Yousef , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/6] sched/deadline: Optimize dl_bw_cpus() Message-ID: <20200430105514.GC19464@codeaurora.org> References: <20200427083709.30262-1-dietmar.eggemann@arm.com> <20200427083709.30262-3-dietmar.eggemann@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200427083709.30262-3-dietmar.eggemann@arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 27, 2020 at 10:37:05AM +0200, Dietmar Eggemann wrote: > Return the weight of the rd (root domain) span in case it is a subset > of the cpu_active_mask. > > Continue to compute the number of CPUs over rd span and cpu_active_mask > when in hotplug. > > Signed-off-by: Dietmar Eggemann > --- > kernel/sched/deadline.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 504d2f51b0d6..4ae22bfc37ae 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -54,10 +54,16 @@ static inline struct dl_bw *dl_bw_of(int i) > static inline int dl_bw_cpus(int i) > { > struct root_domain *rd = cpu_rq(i)->rd; > - int cpus = 0; > + int cpus; > > RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), > "sched RCU must be held"); > + > + if (cpumask_subset(rd->span, cpu_active_mask)) > + return cpumask_weight(rd->span); > + Looks good to me. This is a nice optimization. > + cpus = 0; > + > for_each_cpu_and(i, rd->span, cpu_active_mask) > cpus++; > Do you know why this check is in place? Is it only to cover the case of cpuset_cpu_inactive()->dl_cpu_busy()? Thanks, Pavan > -- > 2.17.1 > -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.