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=-5.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 78B7AC433FE for ; Thu, 10 Dec 2020 08:01:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 386E423D37 for ; Thu, 10 Dec 2020 08:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733263AbgLJIBn (ORCPT ); Thu, 10 Dec 2020 03:01:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgLJIBm (ORCPT ); Thu, 10 Dec 2020 03:01:42 -0500 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E8C5C0613CF for ; Thu, 10 Dec 2020 00:01:02 -0800 (PST) Received: by mail-lj1-x243.google.com with SMTP id s11so5659404ljp.4 for ; Thu, 10 Dec 2020 00:01:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EaxSgwGc3sav/Jepv9lFlJ7IXr1WPiMxzvqTvfFy4fg=; b=Tj1jgPerQPS7CM9LA290bWZTIFQ4w+Enn6sPGDh3Apdb14yarz/+olHKH1AaBJn9zS uSI1BOfU+QfyK5gq95ET7abOMKpli0lAZ7lTmp2AWAOa6WDCSludrLgvaXMtWsTb9Qux oGdb6Mi2Zgd+wSDVo9eoEbZd2bI5e6D0CsBwjoQqaNDQfW4h8klcxMMtIoDAu1yCQA1x ihzBVY1ExV6iDF1oWNduiZphp9hPTfsQWFMbH+HZshAa6E7JSRK3tB4533IwicpYTCLE 90yGntViPXkVAkqjf+lcETwyWVLXaWl15A/L2ttv84iWxEBI6HIOsc3kJ1slqUGxgpKc EbHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EaxSgwGc3sav/Jepv9lFlJ7IXr1WPiMxzvqTvfFy4fg=; b=YgFkEjNA/5iOokSOTP+c23HGdRbyHzYV4o65OO9HCoOCADac243Hz0Qm4+7RhgDGqd 24p9MYvKD9Hqcl4k0IGvRQTk1sNJNAu89CXjGxsj/8DZdznJ7Hwkj79HShY5kJbJWR2b vCRerZpxtmrA3GNcL4T6iVI1vNdvFxsvPPwtNPY95143levUG/uUDcNd206p0LMbhyed A0pQHyIZoh7bgfvhAhEkRRPHQwx9RK5ct9Zy+qPG4BMfmw3rlSZhpf077L5FnS5bhQxP McmOpvUv8yaEVzKk3ghutONQeFjrMslTsxBWHUWuSds48XsqK5ZjqesyzA18d8WGBI3r Kpng== X-Gm-Message-State: AOAM533LEoVk2SAymrwAWG+mgmZHUWXmaqGg0QnaILCKFUUC45slZqfZ RrqtIPWRmL0nPkIUnsWAhk2mgXBYuETgeEXdGcNxsw== X-Google-Smtp-Source: ABdhPJzOgUpJG4+fhPdf2F3nwt/AecWP8IsaQZ6IvObBuSiIq5Gd85PVHwbY2ski+RfTwgtHGhE0AeQ/aYZmlUZ7XsA= X-Received: by 2002:a2e:8396:: with SMTP id x22mr2499130ljg.221.1607587260753; Thu, 10 Dec 2020 00:01:00 -0800 (PST) MIME-Version: 1.0 References: <20201208153501.1467-1-mgorman@techsingularity.net> <20201209143748.GP3371@techsingularity.net> In-Reply-To: <20201209143748.GP3371@techsingularity.net> From: Vincent Guittot Date: Thu, 10 Dec 2020 09:00:49 +0100 Message-ID: Subject: Re: [PATCH 0/4] Reduce scanning of runqueues in select_idle_sibling To: Mel Gorman Cc: Peter Ziljstra , Ingo Molnar , LKML , Aubrey Li , Barry Song , Juri Lelli , Valentin Schneider , Linux-ARM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 9 Dec 2020 at 15:37, Mel Gorman wrote: > > On Tue, Dec 08, 2020 at 03:34:57PM +0000, Mel Gorman wrote: > > Changelog since v1 > > o Drop single-pass patch (vincent) > > o Scope variables used for SIS_AVG_CPU (dietmar) > > o Remove redundant assignment (dietmar > > > > This reduces the amount of runqueue scanning in select_idle_sibling in > > the worst case. > > > > Patch 1 removes SIS_AVG_CPU because it's unused. > > > > Patch 2 moves all SIS_PROP-related calculations under SIS_PROP > > > > Patch 3 improves the hit rate of p->recent_used_cpu to reduce the amount > > of scanning. It should be relatively uncontroversial > > > > Patch 4 returns an idle candidate if one is found while scanning for a > > free core. > > > > Any other objections to the series? Vincent marked 1, 3 and 4 as > reviewed. While patch 2 had some mild cosmetic concerns, I think the > version and how it treats SIS_PROP is fine as it is to keep it > functionally equivalent to !SIS_PROP and without adding too many > SIS_PROP checks. while testing your patchset and Aubrey one on top of tip, I'm facing some perf regression on my arm64 numa system on hackbench and reaim. The regression seems to comes from your patchset but i don't know which patch in particular yet hackbench -l 256000 -g 1 v5.10-rc7 + tip/sched/core 13,255(+/- 3.22%) with your patchset 15.368(+/- 2.74) -15.9% I'm also seeing perf regression on reaim but this one needs more investigation before confirming TBH, I was not expecting regressions. I'm running more test to find which patch is the culprit > > -- > Mel Gorman > SUSE Labs