From patchwork Fri Jun 4 11:05:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Donnefort X-Patchwork-Id: 454429 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 A9663C07E94 for ; Fri, 4 Jun 2021 11:06:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 916FB60FF2 for ; Fri, 4 Jun 2021 11:06:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229690AbhFDLIJ (ORCPT ); Fri, 4 Jun 2021 07:08:09 -0400 Received: from foss.arm.com ([217.140.110.172]:36158 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229667AbhFDLIJ (ORCPT ); Fri, 4 Jun 2021 07:08:09 -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 55EE512FC; Fri, 4 Jun 2021 04:06:23 -0700 (PDT) Received: from e120877-lin.cambridge.arm.com (e120877-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id F37333F73D; Fri, 4 Jun 2021 04:06:21 -0700 (PDT) From: Vincent Donnefort To: peterz@infradead.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, vincent.guittot@linaro.org, qperret@google.com Cc: linux-pm@vger.kernel.org, ionela.voinescu@arm.com, lukasz.luba@arm.com, dietmar.eggemann@arm.com, Vincent Donnefort Subject: [PATCH v3 0/6] EM / PM: Inefficient OPPs Date: Fri, 4 Jun 2021 12:05:55 +0100 Message-Id: <1622804761-126737-1-git-send-email-vincent.donnefort@arm.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org We (Power team in Arm) are working with an experimental kernel for the Google's Pixel4 to evaluate and improve the current mainline performance and energy consumption on a real life device with Android. The SD855 SoC found in this phone has several OPPs that are inefficient. I.e. despite a lower frequency, they have a greater cost. (That cost being fmax * OPP power / OPP freq). This issue is twofold. First of course, running a specific workload at an inefficient OPP is counterproductive since it wastes wasting energy. But also, inefficient OPPs make a performance domain less appealing for task placement than it really is. We evaluated the change presented here by running 30 iterations of Android PCMark "Work 2.0 Performance". While we did not see any statistically significant performance impact, this change allowed to drastically improve the idle time residency. | Running | WFI [1] | Idle | ------------------------+-------------+-----------+-----------+ Little cluster (4 CPUs) | -0.35% | +0.35% | +0.79% | ------------------------+-------------+-----------+-----------+ Medium cluster (3 CPUs) | -6.3% | -18% | +12% | ------------------------+-------------+-----------+-----------+ Big cluster (1 CPU) | -6.4% | -6.5% | +2.8% | ------------------------+-------------+-----------+-----------+ On the SD855, the inefficient OPPs are found on the little cluster. By removing them from the Energy Model, we make the most efficient CPUs more appealing for task placement, helping to reduce the running time for the medium and big CPUs. Increasing idle time is crucial for this platform due to the substantial energy cost differences among the clusters. Also, despite not appearing in the statistics (the idle driver used here doesn't report it), we can speculate that we also improve the cluster idle time. [1] WFI: Wait for interrupt. Changelog since v2: - Add separated support for inefficiencies into CPUFreq. - Collect Reviewed-by for the first patch. Changelog since v1: - Remove the Look-up table as the numbers weren't strong enough to justify the implementation. - Split the patch. Vincent Donnefort (6): PM / EM: Fix inefficient states detection PM / EM: Mark inefficient states cpufreq: Add an interface to mark inefficient frequencies cpufreq: Skip inefficient frequencies in cpufreq_driver_resolve_freq() cpufreq: Mark inefficient frequencies using the Energy Model PM / EM: Skip inefficient states drivers/cpufreq/cpufreq.c | 36 +++++++++++++++++++++++++++++ drivers/cpufreq/freq_table.c | 55 +++++++++++++++++++++++++++++++++++++++++++- include/linux/cpufreq.h | 15 +++++++++++- include/linux/energy_model.h | 50 +++++++++++++++++++++++++++++++++++----- kernel/power/energy_model.c | 27 +++++++++------------- 5 files changed, 159 insertions(+), 24 deletions(-) Reviewed-by: Matthias Kaehlcke Reviewed-by: Matthias Kaehlcke