From patchwork Fri Oct 11 13:44:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas RAILLARD X-Patchwork-Id: 11185505 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 22D3C14DB for ; Fri, 11 Oct 2019 13:45:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0BB552190F for ; Fri, 11 Oct 2019 13:45:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728604AbfJKNp2 (ORCPT ); Fri, 11 Oct 2019 09:45:28 -0400 Received: from foss.arm.com ([217.140.110.172]:60848 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728573AbfJKNp1 (ORCPT ); Fri, 11 Oct 2019 09:45:27 -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 D840B337; Fri, 11 Oct 2019 06:45:26 -0700 (PDT) Received: from e107049-lin.arm.com (e107049-lin.cambridge.arm.com [10.1.195.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 32FFC3F68E; Fri, 11 Oct 2019 06:45:25 -0700 (PDT) From: Douglas RAILLARD To: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, douglas.raillard@arm.com, dietmar.eggemann@arm.com, qperret@qperret.net, patrick.bellasi@matbug.net, dh.han@samsung.com Subject: [RFC PATCH v3 0/6] sched/cpufreq: Make schedutil energy aware Date: Fri, 11 Oct 2019 14:44:54 +0100 Message-Id: <20191011134500.235736-1-douglas.raillard@arm.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Make schedutil cpufreq governor energy-aware. - patch 1 introduces a function to retrieve a frequency given a base frequency and an energy cost margin. - patch 2 links Energy Model perf_domain to sugov_policy. - patch 3 updates get_next_freq() to make use of the Energy Model. - patch 4 adds sugov_cpu_ramp_boost() function. - patch 5 updates sugov_update_(single|shared)() to make use of sugov_cpu_ramp_boost(). - patch 6 introduces a tracepoint in get_next_freq() for testing/debugging. Since it's not a trace event, it's not exposed to userspace in a directly usable way, allowing for painless future updates/removal. The benefits of using the EM in schedutil are twofold: 1) Selecting the highest possible frequency for a given cost. Some platforms can have lower frequencies that are less efficient than higher ones, in which case they should be skipped for most purposes. They can still be useful to give more freedom to thermal throttling mechanisms, but not under normal circumstances. note: the EM framework will warn about such OPPs "hertz/watts ratio non-monotonically decreasing" 2) Driving the frequency selection with power in mind, in addition to maximizing the utilization of the non-idle CPUs in the system. Point 1) is implemented in "PM: Introduce em_pd_get_higher_freq()" and enabled in schedutil by "sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq()". Point 2) is enabled in "sched/cpufreq: Boost schedutil frequency ramp up". It allows using higher frequencies when it is known that the true utilization of currently running tasks is exceeding their previous stable point. The benefits are: * Boosting the frequency when the behavior of a runnable task changes, leading to an increase in utilization. That shortens the frequency ramp up duration, which in turns allows the utilization signal to reach stable values quicker. Since the allowed frequency boost is bounded in energy, it will behave consistently across platforms, regardless of the OPP cost range. * The boost is only transient, and should not impact a lot the energy consumed of workloads with very stable utilization signals. This has been ligthly tested with a rtapp task ramping from 10% to 75% utilisation on a big core. Results are improved by fast ramp-up EWMA [1], since it greatly reduces the oscillation in frequency at first idle when ramping up. [1] [PATCH] sched/fair: util_est: fast ramp-up EWMA on utilization increases Message-ID: <20190620150555.15717-1-patrick.bellasi@arm.com> https://lore.kernel.org/lkml/20190620150555.15717-1-patrick.bellasi@arm.com/ v1 -> v2: * Split the new sugov_cpu_ramp_boost() from the existing sugov_cpu_is_busy() as they seem to seek a different goal. * Implement sugov_cpu_ramp_boost() based on CFS util_avg and util_est_enqueued signals, rather than using idle calls count. This makes the ramp boost much more accurate in finding boost opportunities, and give a "continuous" output rather than a boolean. * Add EM_COST_MARGIN_SCALE=1024 to represent the margin values of em_pd_get_higher_freq(). v2 -> v3: * Check util_avg >= sg_cpu->util_avg in sugov_cpu_ramp_boost_update() to avoid boosting when the utilization is decreasing. * Add a tracepoint for testing. Douglas RAILLARD (6): PM: Introduce em_pd_get_higher_freq() sched/cpufreq: Attach perf domain to sugov policy sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq() sched/cpufreq: Introduce sugov_cpu_ramp_boost sched/cpufreq: Boost schedutil frequency ramp up sched/cpufreq: Add schedutil_em_tp tracepoint include/linux/energy_model.h | 53 ++++++++++++++ include/trace/events/power.h | 9 +++ kernel/sched/cpufreq_schedutil.c | 122 +++++++++++++++++++++++++++++-- 3 files changed, 178 insertions(+), 6 deletions(-)