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=-5.5 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 A4680C433DF for ; Mon, 3 Aug 2020 13:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AF00206D7 for ; Mon, 3 Aug 2020 13:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728023AbgHCN6l (ORCPT ); Mon, 3 Aug 2020 09:58:41 -0400 Received: from foss.arm.com ([217.140.110.172]:57992 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726785AbgHCN6l (ORCPT ); Mon, 3 Aug 2020 09:58:41 -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 42E3230E; Mon, 3 Aug 2020 06:58:40 -0700 (PDT) Received: from localhost (unknown [10.1.198.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D9FDC3F718; Mon, 3 Aug 2020 06:58:39 -0700 (PDT) Date: Mon, 3 Aug 2020 14:58:38 +0100 From: Ionela Voinescu To: Viresh Kumar Cc: rjw@rjwysocki.net, dietmar.eggemann@arm.com, catalin.marinas@arm.com, sudeep.holla@arm.com, will@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, peterz@infradead.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/7] cpufreq: set invariance scale factor on transition end Message-ID: <20200803135838.GB9512@arm.com> References: <20200722093732.14297-1-ionela.voinescu@arm.com> <20200722093732.14297-3-ionela.voinescu@arm.com> <20200730041334.cjg5mc5xpopd2lst@vireshk-mac-ubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200730041334.cjg5mc5xpopd2lst@vireshk-mac-ubuntu> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Viresh, On Thursday 30 Jul 2020 at 09:43:34 (+0530), Viresh Kumar wrote: > On 22-07-20, 10:37, 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. > > I don't think this is deprecated. Sorry, possibly 'deprecated' is a strong word. As far as I knew acpi_cpufreq was recommended more recently for K8/K10 CPUs so that's why I decided not to create a special case for it, also considering that it was not supporting cpufreq-based frequency invariance to begin with. We could support this as well by having a call to arch_set_freq_scale() on the else path in __target_index(). But given that there was only this one user of CPUFREQ_ASYNC_NOTIFICATION, I thought I'd propose this simpler version first. Let me know if my reasoning is wrong. Thank you, Ionela. > > -- > viresh