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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 AF790C46464 for ; Mon, 13 Aug 2018 12:27:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CA6C2178F for ; Mon, 13 Aug 2018 12:27:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6CA6C2178F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729657AbeHMPJX (ORCPT ); Mon, 13 Aug 2018 11:09:23 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33050 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728410AbeHMPJW (ORCPT ); Mon, 13 Aug 2018 11:09:22 -0400 Received: by mail-wm0-f66.google.com with SMTP id i134-v6so281554wmf.0 for ; Mon, 13 Aug 2018 05:27:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=JlIseKsdGdj6x6itYZiSC/IkLSPgz/oVcCsDK3QOYMs=; b=sUrr/2TSIXcVgdWCjgZrsg6GegZxq8PWA/XskjnV0JtMOPsp2GAPHPAve4HagqFGCu k/jABGUpI7v4X41e3skRWtNZFWx9F+JLKuI5d3L2RoBavUOJ6d2EQwqu1vUCBpW5dMt2 GPS5SDUvQ7992vWqhYC35FS6qQE8cIDNEKJqlREd4YNAl8ty2GfK3gOZ4Q4PR5Xm1x1D E9nP++lBNJTIFfh0fVEho6E7it+4J82k0lbhPFgdp0K1tIBy6SMEx7yllOA2iG3mm/aI LeZDHfGqqDTKcZBRCgCHfwofR3Ht3tmLnUzhK5tjlNOsZy/MfVPCFthw2KQyJHxupPCF Bi+w== X-Gm-Message-State: AOUpUlG8QF002cjwaeHSkvET9vbzuAO1B0UKCJ7kmy6mff2jXSsQlt4y 8YVM5ARrPQkkVHwdf1HJa/umvw== X-Google-Smtp-Source: AA+uWPyvc6ZFmJqaovDvrN5STDMw2Y+s+taU618sFdeiEPJgZ0g/m7lCrhEO9CSl7KoUUy+8amk3uA== X-Received: by 2002:a1c:790b:: with SMTP id l11-v6mr7687799wme.66.1534163237855; Mon, 13 Aug 2018 05:27:17 -0700 (PDT) Received: from localhost.localdomain (p200300EF2BCE7D88DAEEE59932720558.dip0.t-ipconnect.de. [2003:ef:2bce:7d88:daee:e599:3272:558]) by smtp.gmail.com with ESMTPSA id h14-v6sm20890333wro.15.2018.08.13.05.27.16 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 13 Aug 2018 05:27:17 -0700 (PDT) Date: Mon, 13 Aug 2018 14:27:14 +0200 From: Juri Lelli To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v3 01/14] sched/core: uclamp: extend sched_setattr to support utilization clamping Message-ID: <20180813122714.GC9851@localhost.localdomain> References: <20180806163946.28380-1-patrick.bellasi@arm.com> <20180806163946.28380-2-patrick.bellasi@arm.com> <20180807095905.GB2288@localhost.localdomain> <20180813121441.GC2605@e110439-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180813121441.GC2605@e110439-lin> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/08/18 13:14, Patrick Bellasi wrote: > On 07-Aug 11:59, Juri Lelli wrote: > > Hi, > > > > Minor comments below. > > > > On 06/08/18 17:39, Patrick Bellasi wrote: > > > > [...] > > > > > + * > > > + * Task Utilization Attributes > > > + * =========================== > > > + * > > > + * A subset of sched_attr attributes allows to specify the utilization which > > > + * should be expected by a task. These attributes allows to inform the > > ^ > > allow > > > > > + * scheduler about the utilization boundaries within which is safe to schedule > > > > Isn't all this more about providing hints than safety? > > Yes, it's "just" hints... will rephrase to make it more clear. > > > > + * the task. These utilization boundaries are valuable information to support > > > + * scheduler decisions on both task placement and frequencies selection. > > > + * > > > + * @sched_util_min represents the minimum utilization > > > + * @sched_util_max represents the maximum utilization > > > + * > > > + * Utilization is a value in the range [0..SCHED_CAPACITY_SCALE] which > > > + * represents the percentage of CPU time used by a task when running at the > > > + * maximum frequency on the highest capacity CPU of the system. Thus, for > > > + * example, a 20% utilization task is a task running for 2ms every 10ms. > > > + * > > > + * A task with a min utilization value bigger then 0 is more likely to be > > > + * scheduled on a CPU which can provide that bandwidth. > > > + * A task with a max utilization value smaller then 1024 is more likely to be > > > + * scheduled on a CPU which do not provide more then the required bandwidth. > > > > Isn't s/bandwidth/capacity/ here, above, and in general where you use > > the term "bandwidth" more appropriate? I wonder if overloading this term > > (w.r.t. how is used with DEADLINE) might create confusion. In this case > > we are not providing any sort of guarantees, it's a hint. > > Yes, you right... here we are not really granting any bandwidth but > just "improving" the bandwidth provisioning by hinting the scheduler > about a certain min/max capacity required. > > The problem related to using capacity is that, from kernel space, > capacity is defined as a static quantity/property of CPUs. Still, I Looks like it's also more inline with EAS terminology (i.e., capacity states).