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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 A74ACC433DF for ; Wed, 29 Jul 2020 09:15:35 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 761AD206D4 for ; Wed, 29 Jul 2020 09:15:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="u2GQVay3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 761AD206D4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=THBz2fcuiPo88H9MKeVxmrbaQPrEcmokTK7l4zWKLKM=; b=u2GQVay3nCiq2ZtmtarJ1vcSp IAJIMBbv9IvBwpHPui7F37tw8RqyS0zweVWOusk69V5wyu2QFDQInBJPx9o5pkiY4l1vnxib86bXq EqCSYki4MhKaQ8ePjgSfhMD002XbXIQ9zK/GeVo6q21/b5jrbYE40kTPSI+Q5VgKdbEug7BFn5Y6D hjritSQhkWHS7C5wnI4eX4oymYCAayX179osVYdhfZlaJpwSDSjQE0oA0Y/qLggPfzo+aSTTzBl0t pTDc9sojXjXn+MjLs4P0Nrrg4n3DBLTpzFRR1x1AcLXmTAlctT5T32J0/zx0uVPx22FYhcISUICCq KjJkHIkMw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0iAG-0007FA-QN; Wed, 29 Jul 2020 09:14:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0iAE-0007EO-Cx for linux-arm-kernel@lists.infradead.org; Wed, 29 Jul 2020 09:14:19 +0000 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 98600101E; Wed, 29 Jul 2020 02:14:17 -0700 (PDT) Received: from localhost (unknown [10.1.198.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3A2E43F718; Wed, 29 Jul 2020 02:14:17 -0700 (PDT) Date: Wed, 29 Jul 2020 10:14:15 +0100 From: Ionela Voinescu To: "Rafael J. Wysocki" Subject: Re: [PATCH v2 2/7] cpufreq: set invariance scale factor on transition end Message-ID: <20200729091405.GB12941@arm.com> References: <20200722093732.14297-1-ionela.voinescu@arm.com> <20200722093732.14297-3-ionela.voinescu@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200729_051418_549092_6D6025B3 X-CRM114-Status: GOOD ( 31.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Linux PM , Peter Zijlstra , Viresh Kumar , "Rafael J. Wysocki" , Russell King - ARM Linux , Linux Kernel Mailing List , Ingo Molnar , Sudeep Holla , Will Deacon , Dietmar Eggemann , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Monday 27 Jul 2020 at 15:52:41 (+0200), Rafael J. Wysocki wrote: > 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). > > [..] > 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. I kept it separate in this version as a proposal to move the call to cpufreq_freq_transition_end() and properly justify it in the commit message. I'll squash it into the previous one, as recommended. Thanks, Ionela. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel