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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 931B4C433E3 for ; Mon, 27 Jul 2020 13:52:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71925206E7 for ; Mon, 27 Jul 2020 13:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595857974; bh=6gvUnAaga1o3SNK5TdyV+zzIUDToUrR4TM83c1UHhP8=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=mSf++5CAPiX62tWHriklXf/nl55nM7jX+VdJTqsGQe2Pt06yPbNYaFqFdySj+mwFj WciIlmhyL4qOA2zza8qV8bO2h6aKXc8CL9R67+ZNRnYL5Yv6wg4dfwUwd2HvB3p3x4 ok+DO5T5rs3CdyICY0O03np7UiyFmrZgU/1IT9pU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728423AbgG0Nwx (ORCPT ); Mon, 27 Jul 2020 09:52:53 -0400 Received: from mail-ot1-f66.google.com ([209.85.210.66]:34598 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726313AbgG0Nwx (ORCPT ); Mon, 27 Jul 2020 09:52:53 -0400 Received: by mail-ot1-f66.google.com with SMTP id a26so3556146otf.1; Mon, 27 Jul 2020 06:52:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MoIlXcMF9D4zeeYXp6UIV7DtFwc5SM0pMI4P1+Jngt0=; b=PhDhku7wcRGPO2TcVoDlkzmXZfOUZdKZJikdeXgJvby1CyQa2Ju/NYj5od0Qz1qWGY t6+zwnDmDyQxYGFHmh5zC6IbN/xodrImP3qBlmujrhHbz8SGyma1S0uW4PdstZtYpgQV XFUt2m4d0e+e8ZJHupyZM1LGwT3FAl+NpoddNs3Bhs33tMIQBnEw3Czg1utvUibDCkdP dgibiznNWyd+ZeYpaifQFOHzGTePuKt6UnrPc2AyGXWZ8BbXl9FvDTFXHUD+g+ycF8BR BLPdjtrEGes1DowckY+uB5QwUCuyp5jKVSLCISVMqlzQvTVlavb4UYIsRgn1E8w9mNGF 9Wlw== X-Gm-Message-State: AOAM5336Tgk48D5bdvpWPVRRiAC2UVEzOrD6E4MpXiikkBcJjJ3sN28d 8B+9G9c1aWwtFFNpqZCTG55qnEckkVUITyazLXk= X-Google-Smtp-Source: ABdhPJz0eM8K7znzqJEUlA6BVvoNfTYawdzuFTAmQYRguizkocRok1Q5QrJvACM7dP3OmxvPAAYrFafrcmdq6gAQET8= X-Received: by 2002:a9d:590a:: with SMTP id t10mr20473486oth.262.1595857971989; Mon, 27 Jul 2020 06:52:51 -0700 (PDT) MIME-Version: 1.0 References: <20200722093732.14297-1-ionela.voinescu@arm.com> <20200722093732.14297-3-ionela.voinescu@arm.com> In-Reply-To: <20200722093732.14297-3-ionela.voinescu@arm.com> From: "Rafael J. Wysocki" Date: Mon, 27 Jul 2020 15:52:41 +0200 Message-ID: Subject: Re: [PATCH v2 2/7] cpufreq: set invariance scale factor on transition end To: Ionela Voinescu Cc: "Rafael J. Wysocki" , Viresh Kumar , Dietmar Eggemann , Catalin Marinas , Sudeep Holla , Will Deacon , Russell King - ARM Linux , Ingo Molnar , Peter Zijlstra , Linux PM , Linux ARM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 22, 2020 at 11:38 AM Ionela Voinescu wrote: > > While the move of the invariance setter calls (arch_set_freq_scale()) > from cpufreq drivers to cpufreq core maintained the previous > functionality for existing drivers that use target_index() and > fast_switch() for frequency switching, it also gives the possibility > of adding support for users of the target() callback, which is exploited > here. > > To be noted that the target() callback has been flagged as deprecated > since: > > commit 9c0ebcf78fde ("cpufreq: Implement light weight ->target_index() routine") > > It also doesn't have that many users: > > cpufreq-nforce2.c:371:2: .target = nforce2_target, > cppc_cpufreq.c:416:2: .target = cppc_cpufreq_set_target, > gx-suspmod.c:439:2: .target = cpufreq_gx_target, > pcc-cpufreq.c:573:2: .target = pcc_cpufreq_target, > > Similarly to the path taken for target_index() calls in the cpufreq core > during a frequency change, all of the drivers above will mark the end of a > frequency change by a call to cpufreq_freq_transition_end(). > > Therefore, cpufreq_freq_transition_end() can be used as the location for > the arch_set_freq_scale() call to potentially inform the scheduler of the > frequency change. > > This change maintains the previous functionality for the drivers that > implement the target_index() callback, while also adding support for the > few drivers that implement the deprecated target() callback. > > Two notes are worthwhile here: > - In __target_index(), cpufreq_freq_transition_end() is called only for > drivers that have synchronous notifications enabled. There is only one > driver that disables them, > > drivers/cpufreq/powernow-k8.c:1142: .flags = CPUFREQ_ASYNC_NOTIFICATION, > > which is deprecated. > > - Despite marking a successful frequency change, many cpufreq drivers > will populate the new policy->cur with the new requested frequency, > although this might not be the one granted by the hardware. > > Therefore, the call to arch_set_freq_scale() is a "best effort" one, > and it is up to the architecture if the new frequency is used in the > new frequency scale factor setting or eventually used by the scheduler. > The architecture is in a better position to decide if it has better > methods to obtain more accurate information regarding the current > frequency (for example the use of counters). > > Signed-off-by: Ionela Voinescu > Cc: Rafael J. Wysocki > Cc: Viresh Kumar > --- > drivers/cpufreq/cpufreq.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index bac4101546db..3497c1cd6818 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -448,6 +448,10 @@ void cpufreq_freq_transition_end(struct cpufreq_policy *policy, > > cpufreq_notify_post_transition(policy, freqs, transition_failed); > > + arch_set_freq_scale(policy->related_cpus, > + policy->cur, > + policy->cpuinfo.max_freq); > + > policy->transition_ongoing = false; > policy->transition_task = NULL; > > @@ -2159,7 +2163,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, > unsigned int relation) > { > unsigned int old_target_freq = target_freq; > - int index, retval; > + int index; > > if (cpufreq_disabled()) > return -ENODEV; > @@ -2190,14 +2194,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, > > index = cpufreq_frequency_table_target(policy, target_freq, relation); > > - retval = __target_index(policy, index); > - > - if (!retval) > - arch_set_freq_scale(policy->related_cpus, > - policy->freq_table[index].frequency, > - policy->cpuinfo.max_freq); > - > - return retval; > + return __target_index(policy, index); > } > EXPORT_SYMBOL_GPL(__cpufreq_driver_target); > > -- I would fold this patch into the previous one. I don't see much reason for it to be separate and it looks like folding it in would cause the previous patch to be simpler.