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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9BAD6C43603 for ; Thu, 5 Dec 2019 14:04:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D82921823 for ; Thu, 5 Dec 2019 14:04:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729478AbfLEOEE (ORCPT ); Thu, 5 Dec 2019 09:04:04 -0500 Received: from foss.arm.com ([217.140.110.172]:35414 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729099AbfLEOEE (ORCPT ); Thu, 5 Dec 2019 09:04:04 -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 42AE5328; Thu, 5 Dec 2019 06:04:03 -0800 (PST) Received: from [192.168.0.9] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9BEE03F68E; Thu, 5 Dec 2019 06:04:00 -0800 (PST) Subject: Re: [RFC 0/3] Introduce per-task latency_tolerance for scheduler hints To: Valentin Schneider , Parth Shah , linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, patrick.bellasi@matbug.net, qais.yousef@arm.com, pavel@ucw.cz, dhaval.giani@oracle.com, qperret@qperret.net, David.Laight@ACULAB.COM, morten.rasmussen@arm.com, pjt@google.com, tj@kernel.org, viresh.kumar@linaro.org, rafael.j.wysocki@intel.com, daniel.lezcano@linaro.org References: <20191125094618.30298-1-parth@linux.ibm.com> <450fc7e2-49d5-d809-281f-7d9a99d3e530@arm.com> From: Dietmar Eggemann Message-ID: <838f233e-fa4c-d5a3-9b50-69e2e121edda@arm.com> Date: Thu, 5 Dec 2019 15:03:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/12/2019 11:49, Valentin Schneider wrote: > > On 05/12/2019 09:24, Dietmar Eggemann wrote: >> On 25/11/2019 10:46, Parth Shah wrote: >>> This patch series is based on the discussion started as the "Usecases for >>> the per-task latency-nice attribute"[1] >>> >>> This patch series introduces a new per-task attribute latency_tolerance to >>> provide the scheduler hints about the latency requirements of the task. >> >> I forgot but is there a chance to have this as a per-taskgroup attribute >> as well? >> > > Peter argued we should go for task attributes first, and then > cgroup/taskgroups later on: > > https://lore.kernel.org/lkml/20190905083127.GA2332@hirez.programming.kicks-ass.net/ OK, I went through this thread again. So Google or we have to provide the missing per-taskgroup API via cpu controller's attributes (like for uclamp) for the EAS usecase. After reading: https://lore.kernel.org/r/20190905114030.GL2349@hirez.programming.kicks-ass.net IMHO the following mapping of the existing Android (binary) latency_sensitive per-taskgroup flag makes sense: latency_sensitive=1 -> latency_tolerance*[-20 .. -1] (less tolerant, more sensitive) latency_sensitive=0 -> latency_tolerance[0 .. 19] (more tolerant, less sensitive) Default value is 0 so not latency_sensitive. * Since we use [-20 .. 19] as values for latency_tolerance we could name it latency_nice. It's shorter ... ?