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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 78791C49EA5 for ; Sat, 26 Jun 2021 09:57:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C17161923 for ; Sat, 26 Jun 2021 09:57:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229741AbhFZJ76 (ORCPT ); Sat, 26 Jun 2021 05:59:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbhFZJ75 (ORCPT ); Sat, 26 Jun 2021 05:59:57 -0400 Received: from mail-qk1-x729.google.com (mail-qk1-x729.google.com [IPv6:2607:f8b0:4864:20::729]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7FE8C061574 for ; Sat, 26 Jun 2021 02:57:34 -0700 (PDT) Received: by mail-qk1-x729.google.com with SMTP id w21so21812645qkb.9 for ; Sat, 26 Jun 2021 02:57:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cjbdKcJqbGe8eTFHsQaTP4RfgkdJNUUzz4KYzjGwNSs=; b=gwh+27RTWHvOcAZhnXRAdQPqj2vzOnGf78tVLcJEDHmB3Cq8x3Z1Ri72oGBHVRDaTf DTKp5N+xtfnTlsBz1BQx7gg40cPFjOkC9rCRG7whZBGg+6fK4pTyzF5sXjzsdu0eVQR9 cb4PiTsR5QWI7n8NvCFLvHwjhLz18VPS1rVhAHn+H4SuP04Bl42N/1KOna5dP6QavgYM TYoi97Cx2Z1XRaC6ZsTsc2od3rTsxmOHSAAyb8A/Zc+7aGG2IrZtAAfVnqosdsUIyNwR jsadUYU/TXXZ/9olz02kTmvMMRo3TCbCZQbFTQlwFSYSuMpKQECgIMXGb5N0DhkoXHJb XiJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=cjbdKcJqbGe8eTFHsQaTP4RfgkdJNUUzz4KYzjGwNSs=; b=hI0Gh99VEOUFa2Te39DduGbSK9p0RfVJeu5hN9J09fI+fcLKjSSK3nxt7xY4e186Pi PFiPhPNkGOI6Wc6cLJp+gE+OHGrY61vfDdKga8HoeV0uYWl1IGufz6S15xgjJCeAc7eW uVKkzMtz7hUETTmmqR5+3hNVUUbwhrXYhHKd3495/jsSuTZTAVvV3pXedF7/txPvQfex wJ7GPGX7yaNr7SQt31c/7+T7oAV8DvuRL2/jdLDJyDoZepe0/g6iuOsKK4OiVpTkbvcF A3HFqynVB+phm5TVJknacCVoeDshr+wNZrYPnmhp3zBu6xobVBXn6yWqTdEmo5P2g3tQ /crQ== X-Gm-Message-State: AOAM530OTwBnm3ZMIIDmFKRxwZZacpJhMt5yMsQNBZ+Er1ErFO5jBCke T8v0IsPmEI3746e98WSqNMA= X-Google-Smtp-Source: ABdhPJxRKNw4gG5Nx0IQKhkhA9TsAUF6hw+Frao37+2PwZUUXn6U2BzhjCJZWWl5L03dp1SH157DCw== X-Received: by 2002:a37:6c4:: with SMTP id 187mr10859499qkg.421.1624701453458; Sat, 26 Jun 2021 02:57:33 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:cde6]) by smtp.gmail.com with ESMTPSA id t187sm6775535qkc.56.2021.06.26.02.57.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Jun 2021 02:57:32 -0700 (PDT) Sender: Tejun Heo Date: Sat, 26 Jun 2021 05:57:28 -0400 From: Tejun Heo To: Josh Don Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Paul Turner , David Rientjes , Oleg Rombakh , Viresh Kumar , Steve Sistare , linux-kernel , Rik van Riel Subject: Re: [PATCH] sched: cgroup SCHED_IDLE support Message-ID: References: <20210608231132.32012-1-joshdon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jun 16, 2021 at 06:01:59PM -0700, Josh Don wrote: > Consider a tree like > > root > / \ > A C > / \ | > B idle t4 > | | \ > t1 t2 t3 > > Here, 'idle' is our cpu.idle cgroup. The following properties would > not be possible if we moved t2/t3 into SCHED_IDLE without the cgroup > interface: > - t1 always preempts t2/t3 on wakeup, but t4 does not > - t2 and t3 have different, non-minimum weights. Technically we could > also achieve this by adding another layer of nested cgroups, but that > starts to make the hierarchy much more complex. > - I've also discussed with Peter a possible extension (vruntime > adjustments) to the current SCHED_IDLE semantics. Similarly to the > first bullet here, we'd need a cgroup idle toggle to achieve certain > scheduling behaviors with this. Would you care to share some concrete use cases? Thank you. -- tejun