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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 DC091C43381 for ; Wed, 20 Jan 2021 12:19:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9DD48206FA for ; Wed, 20 Jan 2021 12:19:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389639AbhATMSl (ORCPT ); Wed, 20 Jan 2021 07:18:41 -0500 Received: from foss.arm.com ([217.140.110.172]:58402 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732790AbhATL63 (ORCPT ); Wed, 20 Jan 2021 06:58:29 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9B153D6E; Wed, 20 Jan 2021 03:57:42 -0800 (PST) Received: from e107158-lin (e107158-lin.cambridge.arm.com [10.1.194.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9B0213F66E; Wed, 20 Jan 2021 03:57:41 -0800 (PST) Date: Wed, 20 Jan 2021 11:57:39 +0000 From: Qais Yousef To: Quentin Perret Cc: "Peter Zijlstra (Intel)" , Dietmar Eggemann , Vincent Guittot , linux-kernel@vger.kernel.org, Valentin Schneider , Morten Rasmussen Subject: Re: [PATCH] sched/eas: Don't update misfit status if the task is pinned Message-ID: <20210120115739.ohe4l2c3ed72suk3@e107158-lin> References: <20210119120755.2425264-1-qais.yousef@arm.com> <20210119164027.drfpmrol3xhf4ckc@e107158-lin> <20210119174244.3p2graxd5gonv4di@e107158-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/19/21 17:50, Quentin Perret wrote: > On Tuesday 19 Jan 2021 at 17:42:44 (+0000), Qais Yousef wrote: > > Hmm IIUC you want to still tag it as misfit so it'll be balanced within the > > little cores in case there's another core with more spare capacity, right? > > Well yes but that's just a special case. But even you have big CPUs in > the affinity mask, you may find that the task fits on none of the CPUs > because they're currently under pressure. But in this case, you may > still want to mark the task as misfit because being under pressure may > be a relatively transient state. Okay. So your thoughts are that if the utilization is above capacity_orig_of() then marking it as misfit is meaningless (taking into account the cpus it is affined to). Which I agree with. But if it is less than capacity_orig_of() but doesn't fit because of pressure ie: util <= capacity_orig_of(cpu) && util > capacity_of(cpu) then we should mark it as misfit as it currently does. I think this makes sense too. There's the margin to consider in the mix here too. And util clamp effects. And the fact this gets called from pick_next_task_fair() which is a hot path :-) Unless someone else beats me to it, I'll send a patch eventually :-) Thanks -- Qais Yousef