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=-5.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 E4A50C433DF for ; Tue, 4 Aug 2020 10:39:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF9DE22C9F for ; Tue, 4 Aug 2020 10:39:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="oN3IV5bZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727932AbgHDKjC (ORCPT ); Tue, 4 Aug 2020 06:39:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726947AbgHDKjB (ORCPT ); Tue, 4 Aug 2020 06:39:01 -0400 Received: from mail-pl1-x643.google.com (mail-pl1-x643.google.com [IPv6:2607:f8b0:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8214AC06174A for ; Tue, 4 Aug 2020 03:39:01 -0700 (PDT) Received: by mail-pl1-x643.google.com with SMTP id q17so22580375pls.9 for ; Tue, 04 Aug 2020 03:39:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=BNGGP8nI26QQvsEtdjfefrmhKzpQ5Kf8DvxYjmO6N1s=; b=oN3IV5bZB9RdAEY0bOaOOp2T+d5/UxbxRkvHrrDySh0FyMAgmapRgFPBrbmz3kBrl3 RjLXUUB09TekcAgaiuL7IhpYURnG5+ogt0T5d55cO5B3bxRQ+Haq0vcnjmA0cA1Du3EC VAiRThtJOmBJbcflkdN5ujxsX6OKjoc1VsD/eZs5Dm0OLV0C/CoprrYF94u6PP/uXQxN +Y6YRe98pTIl6+gjhgYyKUw28/HgNrZKLziwHC6jpFzjn9v73DL79pxYkSAbtt7tDpj3 x+OY5KwvKlj4foIyD9AFeM0I/oqdPMkhDo8BHerWfZbrIRxGlMBNlJfuEM5nr9z/aCed HJSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=BNGGP8nI26QQvsEtdjfefrmhKzpQ5Kf8DvxYjmO6N1s=; b=XIf7RvcBFbpA1tpcWbKGNUC3U49ZPSpbW8pvi6nlE/N3jpznV+8jjepFE0/PlppIP/ s8R7HCSUWcUVFhkbtbGVcne5JHHF7BqWxFecvb9obSGIFCRDt+NXNFyQeXPaV3rrAhk9 YFlcOcuvcwUPQTVxzC7xxBlIw1EtdtYMGCUSSHHiei59oSmL/RcUF+0VrB4ZUT1JkyPl Vvh0Tg+QxGmM7G9dH2jNTfFrD2tLcWR6XW9PGzd2AMVc6sWOew2TnKJ4Ri7Co4EI6X0K IpOiKdSNCwO8MUAFzmTGWt5X226rAR4lnEDz7gM+B+WtCYUHPbSBkxQHdznFvRBZiVJG ATVw== X-Gm-Message-State: AOAM531LwJxOCyfunUCBW/1vI8zY5QWeEf/JpqSbvCkbmOojuwnwUOln f313yte/xodIqWVD+aITV1goSA== X-Google-Smtp-Source: ABdhPJyScsX2xR+pwN0T13dS1iijdQ58el2pg9EUEaeim5L9Peixs0Tx8EVJ5/wuCjT7xdedYbcYBg== X-Received: by 2002:a17:902:b20e:: with SMTP id t14mr851080plr.58.1596537540953; Tue, 04 Aug 2020 03:39:00 -0700 (PDT) Received: from localhost ([122.162.173.150]) by smtp.gmail.com with ESMTPSA id t19sm23230670pfq.179.2020.08.04.03.38.59 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 04 Aug 2020 03:38:59 -0700 (PDT) Date: Tue, 4 Aug 2020 16:08:57 +0530 From: Viresh Kumar To: Lukasz Luba Cc: Sudeep Holla , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, cristian.marussi@arm.com, rjw@rjwysocki.net Subject: Re: [PATCH 0/4] CPUFreq statistics retrieved by drivers Message-ID: <20200804103857.mxgkmt6qmmzejuzb@vireshk-mac-ubuntu> References: <20200729151208.27737-1-lukasz.luba@arm.com> <20200730085333.qubrsv7ufqninihd@vireshk-mac-ubuntu> <20200730091014.GA13158@bogus> <3b3a56e9-29ec-958f-fb3b-c689a9389d2f@arm.com> <20200804053502.35d3x3vnb3mggtqs@vireshk-mac-ubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 04-08-20, 11:29, Lukasz Luba wrote: > On 8/4/20 6:35 AM, Viresh Kumar wrote: > > IIUC, the only concern right now is to capture stats with fast switch ? Maybe we > > can do something else in that case and brainstorm a bit.. > > Correct, the fast switch is the only concern right now and not tracked. We > could fill in that information with statistics data from firmware > with a cpufreq driver help. > > I could make the if from patch 1/4 covering narrowed case, when > fast switch is present, check for drivers stats. > Something like: > -----------8<------------------------------------------------------------ > if (policy->fast_switch_enabled) > if (policy->has_driver_stats) > return cpufreq_stats_present_driver_data(policy, buf); > else > return 0; > -------------->8---------------------------------------------------------- I don't think doing it with help of firmware is the right thing to do here then. For another platform we may not have a firmware which can help us, we need something in the opp core itself for that. Lemme see if I can do something about it. > > Why is firmware the governor here ? Aren't you talking about the simple fast > > switch case only ? > > I used a term 'governor' for the firmware because it makes the final > set for the frequency. It (FW) should respect the frequency value > set using the fast switch. I don't know how other firmware (e.g. Intel) > treats this fast switch value or if they even expose FW stats, though. For Intel I think, Linux is one of the entities that vote for deciding the frequency of the CPUs and the firmware (after taking all such factors into account) chooses a frequency by its own, which must be >= the frequency requested by Linux. > You can read about this statistics region in [1] at: > 4.5.5 Performance domain statistics shared memory region > > > > > Over that, I think this cpufreq stats information isn't parsed by any tool right > > now and tweaking it a bit won't hurt anyone (like if we start capturing things a > > bit differently). So we may not want to worry about breaking userspace ABI here, > > if what we are looking to do is the right thing to do. > > So, there is some hope... IMHO it would be better to have this cpufreq > stats in normal location, rather then in scmi debugfs. I agree. > > I am not sure what notifications are we talking about here. > > There is a notification mechanism described in the SCMI spec [1] at > 4.5.4 Notifications. > We were referring to that mechanism. Ahh, I see. All I was thinking was about the cpufreq specific notifiers :) -- viresh