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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 16E6CC433E6 for ; Mon, 22 Feb 2021 11:01:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2CFA64E5C for ; Mon, 22 Feb 2021 11:01:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230063AbhBVLBR (ORCPT ); Mon, 22 Feb 2021 06:01:17 -0500 Received: from foss.arm.com ([217.140.110.172]:40990 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230224AbhBVLBL (ORCPT ); Mon, 22 Feb 2021 06:01:11 -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 B22E31FB; Mon, 22 Feb 2021 03:00:25 -0800 (PST) Received: from localhost (e108754-lin.cambridge.arm.com [10.1.195.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 508203F73B; Mon, 22 Feb 2021 03:00:25 -0800 (PST) Date: Mon, 22 Feb 2021 11:00:23 +0000 From: Ionela Voinescu To: Viresh Kumar Cc: Rafael Wysocki , Catalin Marinas , Will Deacon , Vincent Guittot , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, Sudeep Holla , Greg Kroah-Hartman Subject: Re: [PATCH V3 2/2] cpufreq: cppc: Add support for frequency invariance Message-ID: <20210222110023.GB4499@arm.com> References: <59f48538545d080cb1c7b201d2d779ab513d2c0c.1611829953.git.viresh.kumar@linaro.org> <20210218163538.GA3105@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210218163538.GA3105@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hey, Some test results: On Thursday 18 Feb 2021 at 16:35:38 (+0000), Ionela Voinescu wrote: [..] > > +static void __init cppc_freq_invariance_init(void) > > +{ [..] > > + > > + ret = cppc_get_perf_ctrs(i, &fb_ctrs); > > + if (!ret) > > + per_cpu(cppc_fi->prev_perf_fb_ctrs, i) = fb_ctrs; > After fixing this one: cppc_fi->prev_perf_fb_ctrs = fb_ctrs; I got the following: Platform: - Juno R2 (CPUs [0-3] are littles, CPUs [4-5] are bigs) + PMU counters, used by CPPC through FFH + userspace/schedutil - Verifying that with userspace governor we see a correct change in scale factor: root@buildroot:~# dmesg | grep FIE [ 6.436770] AMU: CPUs[0-3]: AMU counters WON'T be used for FIE. [ 6.436962] AMU: CPUs[4-5]: AMU counters WON'T be used for FIE. [ 6.451510] CPPC:CPUs[0-5]: CPPC counters will be used for FIE. root@buildroot:~# echo 600000 > policy4/scaling_setspeed [ 353.939495] CPU4: Invariance(cppc) scale: 512. [ 353.939497] CPU5: Invariance(cppc) scale: 512. root@buildroot:~# echo 1200000 > policy4/scaling_setspeed [ 372.683511] CPU5: Invariance(cppc) scale: 1024. [ 372.683518] CPU4: Invariance(cppc) scale: 1024. root@buildroot:~# echo 450000 > policy0/scaling_setspeed [ 641.495513] CPU2: Invariance(cppc) scale: 485. [ 641.495514] CPU1: Invariance(cppc) scale: 485. [ 641.495517] CPU0: Invariance(cppc) scale: 485. [ 641.495542] CPU3: Invariance(cppc) scale: 485. root@buildroot:~# echo 950000 > policy0/scaling_setspeed [ 852.015514] CPU2: Invariance(cppc) scale: 1024. [ 852.015514] CPU1: Invariance(cppc) scale: 1024. [ 852.015517] CPU0: Invariance(cppc) scale: 1024. [ 852.015541] CPU3: Invariance(cppc) scale: 1024. - I ran some benchmarks as well (perf, hackbench, dhrystone) on the same platform, using the userspace governor at fixed frequency, to evaluate the impact of the work we do or don't do on the tick. ./perf bench sched pipe (10 iterations, higher is better, ops/s, comparisons with cpufreq-based FIE) cpufreq-based FIE AMU-based FIE CPPC-based FIE ---------------------------------------------------- 39498.8 40984.7 38893.4 std: 3.766% std: 4.461% std: 0.575% diff: 3.625% diff: -1.556% ./hackbench -l 1000 (10 iterations, lower is better, seconds, comparison with cpufreq-based FIE) cpufreq-based FIE AMU-based FIE CPPC-based FIE ---------------------------------------------------- 6.4207 6.3386 6.7841 std: 7.298% std: 2.252% std: 2.460% diff: -1.295% diff: 5.356% This shows a small regression for the CPPC-based FIE, but within the standard deviation. I ran some dhrystone benchmarks (./dhrystone -t 2/34/5/6/ -l 5000) as well with schedutil governor to understand if an increase in accuracy with the AMU/CPPC counters makes a difference. Given the characteristics of the platform it's no surprise that the results were very similar between the three cases, so I won't bore you with the numbers. Hope it helps, Ionela.