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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 A4D6CC433ED for ; Tue, 4 May 2021 09:08:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84BCA610A1 for ; Tue, 4 May 2021 09:08:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230072AbhEDJJF (ORCPT ); Tue, 4 May 2021 05:09:05 -0400 Received: from foss.arm.com ([217.140.110.172]:55944 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229905AbhEDJJE (ORCPT ); Tue, 4 May 2021 05:09:04 -0400 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 60D0DED1; Tue, 4 May 2021 02:08:09 -0700 (PDT) Received: from e120189.arm.com (unknown [10.57.63.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id EAC933F73B; Tue, 4 May 2021 02:08:05 -0700 (PDT) From: Pierre Gondois To: linux-kernel@vger.kernel.org, xuewen.yan@unisoc.com, qperret@qperret.net, Lukasz.Luba@arm.com, dietmar.eggemann@arm.com Cc: Vincent.Donnefort@arm.com, Pierre Gondois , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com Subject: [PATCH v3 0/2] sched/fair: find_energy_efficient_cpu() enhancements Date: Tue, 4 May 2021 10:07:41 +0100 Message-Id: <20210504090743.9688-1-Pierre.Gondois@arm.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org V2: - Split the patch in 2. [Quentin] - Add testing results to the cover-letter. [Dietmar] - Put back 'rcu_read_unlock()' to unlock the rcu earlier. [Dietmar] - Various comments. [Dietmar/Quentin] V3: - Layout/phrasing. [Dietmar] This patchset prevents underflows in find_energy_efficient_cpu(). This is done in the second patch: sched/fair: Fix negative energy delta in find_energy_efficient_cpu() The first patch: sched/fair: Only compute base_energy_pd if necessary prevents an unnecessary call to compute_energy() if no CPU is available in a performance domain (pd). When looping over the pds, it also allows to gather the calls to compute_energy(), reducing the chances of having utilization signals being concurrently updated and having a 'negative delta'. The energy tests of the initial EAS enablement at: https://lkml.kernel.org/r/20181203095628.11858-1-quentin.perret@arm.com have been executed using LISA on a Juno-r2 (2xA57 + 4xA53). To recall the test: "10 iterations of between 10 and 50 periodic rt-app tasks (16ms period, 5% duty-cycle) for 30 seconds with energy measurement. Unit is Joules. The goal is to save energy, so lower is better." "Energy is measured with the onboard energy meter. Numbers include consumption of big and little CPUs." +----------+-----------------+-------------------------+ | | Without patches | With patches | +----------+--------+--------+------------------+------+ | Tasks nb | Mean | CI* | Mean | CI* | +----------+--------+--------+------------------+------+ | 10 | 6.57 | 0.24 | 6.46 (-1.63%) | 0.27 | | 20 | 12.44 | 0.21 | 12.44 (-0.01%) | 0.14 | | 30 | 19.10 | 0.78 | 18.75 (-1.85%) | 0.15 | | 40 | 27.27 | 0.53 | 27.35 (+0.31%) | 0.33 | | 50 | 36.55 | 0.42 | 36.28 (-0.74%) | 0.42 | +----------+-----------------+-------------------------+ CI: confidence interval For each line, the intervals of values w/ w/o the patches are overlapping (consider Mean +/- CI). Thus, the energy results shouldn't have been impacted. Pierre Gondois (2): sched/fair: Only compute base_energy_pd if necessary sched/fair: Fix negative energy delta in find_energy_efficient_cpu() kernel/sched/fair.c | 68 ++++++++++++++++++++++++++------------------- 1 file changed, 39 insertions(+), 29 deletions(-) -- 2.17.1