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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 F1117C433DB for ; Mon, 1 Mar 2021 18:12:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C15F364FAE for ; Mon, 1 Mar 2021 18:12:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239407AbhCASML (ORCPT ); Mon, 1 Mar 2021 13:12:11 -0500 Received: from foss.arm.com ([217.140.110.172]:33554 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234461AbhCAQfC (ORCPT ); Mon, 1 Mar 2021 11:35:02 -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 200571063; Mon, 1 Mar 2021 08:34:13 -0800 (PST) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 92B263F73C; Mon, 1 Mar 2021 08:34:11 -0800 (PST) Subject: Re: [PATCH v2] sched/pelt: Fix task util_est update filtering To: Peter Zijlstra , Vincent Donnefort Cc: mingo@readhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, patrick.bellasi@matbug.net, valentin.schneider@arm.com References: <20210225165820.1377125-1-vincent.donnefort@arm.com> From: Dietmar Eggemann Message-ID: Date: Mon, 1 Mar 2021 17:34:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/02/2021 09:41, Peter Zijlstra wrote: > On Thu, Feb 25, 2021 at 04:58:20PM +0000, Vincent Donnefort wrote: >> +#define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100) >> + >> /* >> - * Check if a (signed) value is within a specified (unsigned) margin, >> + * Check if a (signed) value is within the (unsigned) util_est margin, >> * based on the observation that: >> * >> * abs(x) < y := (unsigned)(x + y - 1) < (2 * y - 1) >> * >> - * NOTE: this only works when value + maring < INT_MAX. >> + * NOTE: this only works when value + UTIL_EST_MARGIN < INT_MAX. >> */ >> -static inline bool within_margin(int value, int margin) >> +static inline bool util_est_within_margin(int value) >> { >> - return ((unsigned int)(value + margin - 1) < (2 * margin - 1)); >> + return ((unsigned int)(value + UTIL_EST_MARGIN - 1) < >> + (2 * UTIL_EST_MARGIN - 1)); >> } > >> - if (within_margin(last_ewma_diff, (SCHED_CAPACITY_SCALE / 100))) >> + if (util_est_within_margin(last_ewma_diff)) { > > What was the purpose of this change? What was a generic helper is now > super specific. I guess because it was only ever used in util_est for last_ewma_diff. It's now used for last_ewma_diff and last_enqueued_diff, still only for util_est though and both times with the same margin (SCHED_CAPACITY_SCALE / 100)). Vincent D. should be back on Wed from hols.