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=-2.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 EFDF5C004C9 for ; Tue, 7 May 2019 15:04:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B41ED20578 for ; Tue, 7 May 2019 15:04:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726573AbfEGPEa (ORCPT ); Tue, 7 May 2019 11:04:30 -0400 Received: from foss.arm.com ([217.140.101.70]:56820 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725843AbfEGPEa (ORCPT ); Tue, 7 May 2019 11:04:30 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 96DDA374; Tue, 7 May 2019 08:04:29 -0700 (PDT) Received: from queper01-lin (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 17B743F5C1; Tue, 7 May 2019 08:04:26 -0700 (PDT) Date: Tue, 7 May 2019 16:04:25 +0100 From: Quentin Perret To: luca abeni Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , "Rafael J . Wysocki" , Ingo Molnar , Peter Zijlstra , Vincent Guittot , "Paul E . McKenney" , Joel Fernandes , Luc Van Oostenryck , Morten Rasmussen , Juri Lelli , Daniel Bristot de Oliveira , Patrick Bellasi , Tommaso Cucinotta Subject: Re: [RFC PATCH 2/6] sched/dl: Capacity-aware migrations Message-ID: <20190507150423.xid3j6wcjdbtavdf@queper01-lin> References: <20190506044836.2914-1-luca.abeni@santannapisa.it> <20190506044836.2914-3-luca.abeni@santannapisa.it> <20190507133528.ia4p3medvtg4z5az@queper01-lin> <20190507161733.1a26419b@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190507161733.1a26419b@nowhere> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 07 May 2019 at 16:17:33 (+0200), luca abeni wrote: > Hi Quentin, > > On Tue, 7 May 2019 14:35:28 +0100 > Quentin Perret wrote: > > > Hi Luca, > > > > On Monday 06 May 2019 at 06:48:32 (+0200), Luca Abeni wrote: > > > +static inline int dl_task_fit(const struct sched_dl_entity *dl_se, > > > + int cpu, u64 *c) > > > +{ > > > + u64 cap = (arch_scale_cpu_capacity(NULL, cpu) * > > > arch_scale_freq_capacity(cpu)) >> SCHED_CAPACITY_SHIFT; > > > > I'm a little bit confused by this use of arch_scale_freq_capacity() > > here. IIUC this means you would say a big DL task doesn't fit on a big > > CPU just because it happens to be running at a low frequency when this > > function is called. Is this what we want ? > > The idea of this approach was to avoid frequency switches when > possible; so, I wanted to check if the task fits on a CPU core at its > current operating frequency. > > > > If the frequency is low, we can (probably) raise it to accommodate > > this DL task so perhaps we should say it fits ? > > In a later patch, if the task does not fit on any core (at its current > frequency), the task is moved to the core having the maximum capacity > (without considering the operating frequency --- at least, this was my > intention when I wrote the patches :) Ah, I see, patches 05-06. I'll go have a look then ! Thanks, Quentin