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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BBA0C433F5 for ; Tue, 15 Mar 2022 17:07:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350468AbiCORJG (ORCPT ); Tue, 15 Mar 2022 13:09:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242353AbiCORJD (ORCPT ); Tue, 15 Mar 2022 13:09:03 -0400 Received: from mail-lf1-x135.google.com (mail-lf1-x135.google.com [IPv6:2a00:1450:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C0A4639C for ; Tue, 15 Mar 2022 10:07:50 -0700 (PDT) Received: by mail-lf1-x135.google.com with SMTP id w7so34153246lfd.6 for ; Tue, 15 Mar 2022 10:07:50 -0700 (PDT) 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=8OwTI3UtdnqUESoKlohwZIL3xHHO7DnZYdKpKk+9gN8=; b=T+8KXwJOwXVyiorrQqYAEcy7XHZKpO6ojbZEyPTVsXpl1EMi8Uklm6Fupyz0/zXQ3t s70j/5coRJYMChxYcdoJSi+mobg6Zrk0EBVr+odk8Rhko8jE54yeCVH50apvJx5fuCGB UXVSqgIT0M14ZwNPtk8DGNiXL2zvr8UU9JkRdUdrP+W1VQB7fwT50tMM9xi8hOVzrRNc 15dGLzoO0y/G+rc/+CTXwpQ+ONpVfKJdegMC3A1VjEUb1Ym5rc9t9Ul/HO09WU//bNbs cbWymF7b899NetmXvns0IyzfU3tn8PJuop1pZnP713Xa6vWWvCyrLlE16b2g97HAU6xI 50iA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=8OwTI3UtdnqUESoKlohwZIL3xHHO7DnZYdKpKk+9gN8=; b=8Pi+3KRSahG69sT/H5aqNYupIhSL4WHvKQaL1FFxwXwWZjgW7yTLwCbxzoyRbC3Y4f IL3qkK/37hmslrcZJnzfBCDzmJUT+83b5nH4G/57/q09gyjEKieUJ76CgctHfqr/DxF+ RqATWMOkrwyp0c+pMq3tCLvXxtBNKyHRlCuFXXzb7Ib9MB+/DTrdPyhI+wabKmF8pXOO uQW1aJCez/USNwMqNizf2TwUaL6puLAa5QJDuXbkDVuoZur78OlsJy0oFNBAIHHOQ8lf vV686wU7fVde47fu3QJUtXPXvjbo4gLtTDNa4Tgo5Z+tQ5ZLDlx10CSsnCOniJJquEqu zIVA== X-Gm-Message-State: AOAM531Xam0z9qNDmB9DbQDQg57TLIBuNEi7y5x3fhHUuDk85JU3Z5xh JiqhfaMgaC5173Yy8Utkh4QWo6ULcnEXTR9sltoAgw== X-Google-Smtp-Source: ABdhPJw9hAhG0DNB8EFqKWQtVHVToNYXk82biM84hBl1YWN/4P4/jEnTwAL/yHV5wIyR52SApMeCUusq51PrfjEraBI= X-Received: by 2002:a05:6512:3f99:b0:447:1ef5:408a with SMTP id x25-20020a0565123f9900b004471ef5408amr17117476lfa.490.1647364068619; Tue, 15 Mar 2022 10:07:48 -0700 (PDT) MIME-Version: 1.0 References: <20220311161406.23497-1-vincent.guittot@linaro.org> <20220311161406.23497-7-vincent.guittot@linaro.org> In-Reply-To: From: Vincent Guittot Date: Tue, 15 Mar 2022 18:07:37 +0100 Message-ID: Subject: Re: [RFC 6/6] sched/fair: Add sched group latency support To: Josh Don Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , Mel Gorman , linux-kernel , parth@linux.ibm.com, Qais Yousef , "Hyser,Chris" , Pavan Kondeti , Valentin Schneider , patrick.bellasi@matbug.net, David.Laight@aculab.com, Paul Turner , pavel@ucw.cz, Tejun Heo , Dhaval Giani , qperret@google.com, Tim Chen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Mar 2022 at 01:59, Josh Don wrote: > > On Fri, Mar 11, 2022 at 8:15 AM Vincent Guittot > wrote: > > > [snip] > > > > static struct cftype cpu_legacy_files[] = { > > @@ -10649,6 +10673,11 @@ static struct cftype cpu_legacy_files[] = { > > .read_s64 = cpu_idle_read_s64, > > .write_s64 = cpu_idle_write_s64, > > }, > > + { > > + .name = "latency", > > + .read_s64 = cpu_latency_read_s64, > > + .write_s64 = cpu_latency_write_s64, > > + }, > > #endif > > #ifdef CONFIG_CFS_BANDWIDTH > > { > > @@ -10866,6 +10895,18 @@ static struct cftype cpu_files[] = { > > .read_s64 = cpu_idle_read_s64, > > .write_s64 = cpu_idle_write_s64, > > }, > > + { > > + .name = "latency", > > + .flags = CFTYPE_NOT_ON_ROOT, > > + .read_s64 = cpu_latency_read_s64, > > + .write_s64 = cpu_latency_write_s64, > > + }, > > + { > > + .name = "latency.nice", > > + .flags = CFTYPE_NOT_ON_ROOT, > > + .read_s64 = cpu_latency_nice_read_s64, > > + .write_s64 = cpu_latency_nice_write_s64, > > + }, > > Something I considered when adding cpu.idle was that negative values > could be used to indicate increasing latency sensitivity. Folding the > above latency property into cpu.idle could help consolidate the > "latency" behavior, especially given that it shouldn't really be > possible to configure an entity as both latency sensitive and idle. The range of latency nice is [-19:20] and it doesn't touch on the weight whereas sched_idle behavior impacts both the shares and the preemption so I was afraid of possible confusion with what latency nice is doing