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[2620:137:e000::1:20]) by mx.google.com with ESMTP id hy21-20020a1709068a7500b006df76385d79si2344276ejc.537.2022.03.25.06.24.24; Fri, 25 Mar 2022 06:24:50 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352264AbiCXR1L (ORCPT + 99 others); Thu, 24 Mar 2022 13:27:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352267AbiCXR1H (ORCPT ); Thu, 24 Mar 2022 13:27:07 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 87893996B8 for ; Thu, 24 Mar 2022 10:25:33 -0700 (PDT) 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 E4CD81515; Thu, 24 Mar 2022 10:25:32 -0700 (PDT) Received: from wubuntu (unknown [10.57.71.95]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 496133F73B; Thu, 24 Mar 2022 10:25:30 -0700 (PDT) Date: Thu, 24 Mar 2022 17:25:28 +0000 From: Qais Yousef To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org, parth@linux.ibm.com, chris.hyser@oracle.com, pkondeti@codeaurora.org, Valentin.Schneider@arm.com, patrick.bellasi@matbug.net, David.Laight@aculab.com, pjt@google.com, pavel@ucw.cz, tj@kernel.org, dhaval.giani@oracle.com, qperret@google.com, tim.c.chen@linux.intel.com Subject: Re: [PATCH 0/6] Add latency_nice priority Message-ID: <20220324172528.lrjiehsqrwvnwg2x@wubuntu> References: <20220311161406.23497-1-vincent.guittot@linaro.org> <20220322163911.3jge4unswuap3pjh@wubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/23/22 16:32, Vincent Guittot wrote: > On Tue, 22 Mar 2022 at 17:39, Qais Yousef wrote: > > > > Hi Vincent > > > > Thanks for reviving this patchset! > > > > On 03/11/22 17:14, Vincent Guittot wrote: > > > This patchset restarts the work about adding a latency nice priority to > > > describe the latency tolerance of cfs tasks. > > > > > > The patches [1-4] have been done by Parth: > > > https://lore.kernel.org/lkml/20200228090755.22829-1-parth@linux.ibm.com/ > > > > > > I have just rebased and moved the set of latency priority outside the > > > priority update. I have removed the reviewed tag because the patches > > > are 2 years old. > > > > AFAIR the blocking issue we had then is on agreement on the interface. Has this > > been resolved now? I didn't see any further discussion since then. > > I think that there was an agreement about using a latency nice > priority in the range [-20:19] with -20 meaning sensitive to latency > whereas 19 means that task doesn't care about scheduling latency. The > open point was about how to use this input in the scheduler with some > behavior being opposed. What I remember is that the problem was to consolidate on use cases then discuss interfaces. See https://lwn.net/Articles/820659/ " Youssef said that the interface to all of this is the sticking point. Thomas Gleixner agreed, saying that the -20..19 range "requires a crystal ball" to use properly. Zijlstra repeated his call to enumerate the use cases before getting into the interface details. Giani repeated that the interface does not look correct now, and agreed that a more comprehensive look at the use cases was needed. Things were being done backwards currently, he said. " > > > > > > > > > The patches [5-6] use latency nice priority to decide if a cfs task can > > > preempt the current running task. Patch 5 gives some tests results with > > > cyclictests and hackbench to highlight the benefit of latency nice > > > priority for short interactive task or long intensive tasks. > > > > This is a new use case AFAICT. For Android, we want to do something in EAS path > > I don't think it's new, it's about being able to run some tasks in I meant new use case to latency-nice interface. I don't think we had this in any of our discussions before? I don't mind it, but it'd be good to clarify if it has any relation about the other use cases and what should happen to the other use cases. Thanks -- Qais Yousef