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=-5.8 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 B95F3C433FE for ; Fri, 4 Dec 2020 15:24:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CC6F22B42 for ; Fri, 4 Dec 2020 15:24:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730601AbgLDPYl (ORCPT ); Fri, 4 Dec 2020 10:24:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbgLDPYl (ORCPT ); Fri, 4 Dec 2020 10:24:41 -0500 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3D25C0613D1 for ; Fri, 4 Dec 2020 07:24:00 -0800 (PST) Received: by mail-ot1-x344.google.com with SMTP id y24so5512539otk.3 for ; Fri, 04 Dec 2020 07:24:00 -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=yb5cBIaAgEvdW65I3gct0bwLgiUK91VDJcIaRSW+Ncc=; b=sRKUpMlQ59l+3cbTx0lnBOA3ymo9+Yci+V54ir0P78wJxW+jgWpMtSkcmozBRfO4V/ Sie5dSF+3Et8P0ZTea3qFcxJm0dLd5nqfSoN2Btx7kkTU2aUdSe6sKV80LoGYiJ5z8QG oTI+oDZHZBfKukdaoViC/uS2Q6ec4WFM+VVf44yf629jUqIV7ni8nUi3FMRTTz68xSDb CwPz8SsD9/i2TLe9OPzgRXuJt9q1/crJYdvcVhKotWVuRfrRjZC01RnYKF37Ud50EAwN K3sGOA6ZfVH9VRiQIJWq+8GfLYX9C3/d0FsTSZd4cLaL5Ak5hJ/A7MDn2Jjo8D1GR8Xa EZBQ== 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=yb5cBIaAgEvdW65I3gct0bwLgiUK91VDJcIaRSW+Ncc=; b=EZn6RM1F9owZaeILcL7mwK6LSAYuNJuG6/OmG+pI+/1a1yoA2cPUiDGrbD/CaEXSBN 3Hi31XLb0O2rCQt8AqslnbUvewT6Xv2eeoAbBc41NA2apvzJEiFDKiYFbyCy6w+wmYTA VIATiaqiXydg9K27ubA0ExrsNr/UEVYSfFrlSa+wBB+WuU8FwimmVhW5bxxOoUD04V2x NJPEt0mCv91G1K1L+mSP6LTHvHu3llYXgRgK5l7dhMsLQcEDplwR95I2EVYTTEHnYS50 6uDsb4B2S6yOgMGtVWIK4uDUezHMqBEniN4lSH5l/BREKeU4+hapLZ7KJNnHOZ1L9vHP uXcQ== X-Gm-Message-State: AOAM532N6SlMntQD2xPMzPsffzs111MjHfGOBgT66/9uGuiy9WqVX7IS nGgvcMF1z0Hjkq/AU7KolA5BNcOuVVXMi2vnLF5imw== X-Google-Smtp-Source: ABdhPJz4ZiGgzBwku8kZ+7K3e1xIWnzb2buQ4O4MkOqVJW7ksN5oxo6OTCx9XRDlmhVV8vN84bTjfUB9O18ezhC/zLo= X-Received: by 2002:a05:6830:2ef:: with SMTP id r15mr4106721ote.261.1607095440313; Fri, 04 Dec 2020 07:24:00 -0800 (PST) MIME-Version: 1.0 References: <20201203141124.7391-1-mgorman@techsingularity.net> <20201203141124.7391-7-mgorman@techsingularity.net> <20201203175204.GY3371@techsingularity.net> <20201204113030.GZ3371@techsingularity.net> <3d8a6d19-afac-dc93-127d-da6505402cdf@linux.intel.com> <20201204143115.GB3371@techsingularity.net> In-Reply-To: <20201204143115.GB3371@techsingularity.net> From: Vincent Guittot Date: Fri, 4 Dec 2020 16:23:48 +0100 Message-ID: Subject: Re: [PATCH 06/10] sched/fair: Clear the target CPU from the cpumask of CPUs searched To: Mel Gorman Cc: "Li, Aubrey" , LKML , Barry Song , Ingo Molnar , Peter Ziljstra , 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 Fri, 4 Dec 2020 at 15:31, Mel Gorman wrote: > > On Fri, Dec 04, 2020 at 02:47:48PM +0100, Vincent Guittot wrote: > > > IIUC, select_idle_core and select_idle_cpu share the same cpumask(select_idle_mask)? > > > If the target's sibling is removed from select_idle_mask from select_idle_core(), > > > select_idle_cpu() will lose the chance to pick it up? > > > > This is only relevant for patch 10 which is not to be included IIUC > > what mel said in cover letter : "Patches 9 and 10 are stupid in the > > context of this series." > > > > Patch 10 was stupid in the context of the prototype because > select_idle_core always returned a CPU. A variation ended up being > reintroduced at the end of the Series Yet To Be Posted so that SMT siblings > are cleared during select_idle_core() but select_idle_cpu() still has a > mask with unvisited CPUs to consider if no idle cores are found. > > As far as I know, this would still be compatible with Aubrey's idle > cpu mask as long as it's visited and cleared between select_idle_core > and select_idle_cpu. It relaxes the contraints on Aubrey to some extent > because the idle cpu mask would be a hint so if the information is out > of date, an idle cpu may still be found the normal way. But even without patch 10, just replacing sched_domain_span(sd) by sds_idle_cpus(sd->shared) will ensure that sis loops only on cpus that get a chance to be idle so select_idle_core is likely to return an idle_candidate > > -- > Mel Gorman > SUSE Labs