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[2620:137:e000::3:5]) by mx.google.com with ESMTPS id l12-20020a170903120c00b001d0087bbf19si5825185plh.440.2023.12.10.23.55.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 23:55:24 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) client-ip=2620:137:e000::3:5; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=arm.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by groat.vger.email (Postfix) with ESMTP id 5FEAA8068A0D; Sun, 10 Dec 2023 23:55:21 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at groat.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233882AbjLKHzD (ORCPT + 99 others); Mon, 11 Dec 2023 02:55:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229570AbjLKHzB (ORCPT ); Mon, 11 Dec 2023 02:55:01 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 63BF4F4; Sun, 10 Dec 2023 23:55:08 -0800 (PST) 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 8C14B1007; Sun, 10 Dec 2023 23:55:54 -0800 (PST) Received: from [10.57.84.143] (unknown [10.57.84.143]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0EC273F5A1; Sun, 10 Dec 2023 23:55:05 -0800 (PST) Message-ID: <8ee6425a-0a0e-4391-9fd3-8fe74c809772@arm.com> Date: Mon, 11 Dec 2023 07:56:09 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] sched/fair: Be less aggressive in calling cpufreq_update_util() To: Qais Yousef Cc: linux-kernel@vger.kernel.org, Vincent Guittot , Viresh Kumar , "Rafael J. Wysocki" , Dietmar Eggemann , linux-pm@vger.kernel.org, Ingo Molnar , Wei Wang , Rick Yiu , Chung-Kai Mei , Hongyan Xia , Peter Zijlstra References: <20231208015242.385103-1-qyousef@layalina.io> <20231208015242.385103-2-qyousef@layalina.io> <20231210205156.kausxdcwsydggwie@airbuntu> Content-Language: en-US From: Lukasz Luba In-Reply-To: <20231210205156.kausxdcwsydggwie@airbuntu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on groat.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (groat.vger.email [0.0.0.0]); Sun, 10 Dec 2023 23:55:21 -0800 (PST) On 12/10/23 20:51, Qais Yousef wrote: > On 12/08/23 10:05, Lukasz Luba wrote: >> Hi Qais, >> >> On 12/8/23 01:52, Qais Yousef wrote: >> >> [snip] >> >>> @@ -6704,14 +6677,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) >>> */ >>> util_est_enqueue(&rq->cfs, p); >>> - /* >>> - * If in_iowait is set, the code below may not trigger any cpufreq >>> - * utilization updates, so do it here explicitly with the IOWAIT flag >>> - * passed. >>> - */ >>> - if (p->in_iowait) >>> - cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT); >>> - >> >> Why this io wait boost is considered as the $subject says 'aggressive' >> calling? > > This will trigger a frequency update along with the iowait boost. Did I miss > something? Yes, it will change CPU freq and it was the main goal for this code path. We have tests which check how that works on different memory types. Why do you want to remove it? Did you run some tests (e.g. fio, gallery, etc) to check if you still have a decent performance out some new ufs/nvme memories? Beata & Dietmar have presented at LPC2021 a proposal to have a per-task io boost, with a bit more controllable way of the trade off power vs. performance [1]. IMO the io wait boost could evolve, not simply die. Regards, Lukasz [1] https://lpc.events/event/11/contributions/1042/