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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FE1AC04A94 for ; Mon, 14 Aug 2023 07:28:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233736AbjHNH1i (ORCPT ); Mon, 14 Aug 2023 03:27:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234299AbjHNH1b (ORCPT ); Mon, 14 Aug 2023 03:27:31 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CFA73E73; Mon, 14 Aug 2023 00:27:25 -0700 (PDT) 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 B9CE92F4; Mon, 14 Aug 2023 00:28:07 -0700 (PDT) Received: from e129154.nice.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 013CE3F64C; Mon, 14 Aug 2023 00:27:21 -0700 (PDT) Date: Mon, 14 Aug 2023 09:27:17 +0200 From: Beata Michalska To: Will Deacon Cc: Sudeep Holla , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, mark.rutland@arm.com, rafael@kernel.org, viresh.kumar@linaro.org, ionela.voinescu@arm.com, sumitg@nvidia.com, yang@os.amperecomputing.com Subject: Re: [PATCH] arm64: Provide an AMU-based version of arch_freq_get_on_cpu Message-ID: References: <20230606155754.245998-1-beata.michalska@arm.com> <20230607095856.7nyv7vzuehceudnl@bogus> <20230727095604.GA18721@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230727095604.GA18721@willie-the-truck> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thu, Jul 27, 2023 at 10:56:05AM +0100, Will Deacon wrote: > On Wed, Jun 07, 2023 at 03:00:49PM +0100, Beata Michalska wrote: > > On Wed, Jun 07, 2023 at 10:58:56AM +0100, Sudeep Holla wrote: > > > On Tue, Jun 06, 2023 at 04:57:54PM +0100, Beata Michalska wrote: > > > > With the Frequency Invariance Engine (FIE) being already wired up with > > > > sched tick and making use of relevant (core counter and constant > > > > counter) AMU counters, getting the current frequency for a given CPU > > > > on supported platforms, can be achieved by utilizing the frequency scale > > > > factor which reflects an average CPU frequency for the last tick period > > > > length. > > > > > > > > With that at hand, arch_freq_get_on_cpu dedicated implementation > > > > gets enrolled into cpuinfo_cur_freq policy sysfs attribute handler, > > > > which is expected to represent the current frequency of a given CPU, > > > > as obtained by the hardware. This is exactly the type of feedback that > > > > cycle counters provide. > > > > > > > > In order to avoid calling arch_freq_get_on_cpu from the scaling_cur_freq > > > > attribute handler for platforms that do provide cpuinfo_cur_freq, and > > > > yet keeping things intact for those platform that do not, its use gets > > > > conditioned on the presence of cpufreq_driver (*get) callback (which also > > > > seems to be the case for creating cpuinfo_cur_freq attribute). > > > > > > > > > > LGTM, > > > > > > Reviewed-by: Sudeep Holla > > > > > Thanks for the review. > > > However I fail to understand if both the changes are dependent ? > > > Can this be split into 2 patches ? I fail to see the dependency, what > > > am I missing ? Even if there is some dependency to get arch value > > > (arch_freq_get_on_cpu() from show_cpuinfo_cur_freq()), you can push > > > that change first followed by the arm64 change as 2 different change. > > > > > I guess I could split the patch into two parts: > > 1. adding implementation for the arch_freq_get_on_cpu > > 2. wiring it up with the cpufreq relevant attrib handlers > > > > or the other way round (if that's what you have in mind). > > > > Will wait a bit for any further comments before pushing new v. > > Are you still planning on a v2? Apologies for late reply, 've been away for a while and then got bit swamped. I do not think there will be v2 unless I'll find reasonable way to handle cases as one mentioned in [1]. --- BR B. [1] https://lore.kernel.org/linux-arm-kernel/691d3eb2-cd93-f0fc-a7a4-2a8c0d44262c@nvidia.com/T/#m4e74cb5a0aaa353c60fedc6cfb95ab7a6e381e3c > > Will