Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933249AbdGKPNE (ORCPT ); Tue, 11 Jul 2017 11:13:04 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:46406 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932597AbdGKPNB (ORCPT ); Tue, 11 Jul 2017 11:13:01 -0400 Subject: Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support To: "Rafael J. Wysocki" Cc: Viresh Kumar , Peter Zijlstra , "Rafael J. Wysocki" , Linux Kernel Mailing List , Linux PM , Russell King - ARM Linux , Greg Kroah-Hartman , Russell King , Catalin Marinas , Will Deacon , Juri Lelli , Vincent Guittot , Morten Rasmussen References: <20170706094948.8779-1-dietmar.eggemann@arm.com> <20170711060106.GL2928@vireshk-i7> <45224055-7bf1-243b-9366-0f2d3442ef59@arm.com> <1883025.xinGhbAdMS@aspire.rjw.lan> From: Dietmar Eggemann Message-ID: <1cfe639d-6402-ea64-f502-dcf07083569f@arm.com> Date: Tue, 11 Jul 2017 16:12:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1883025.xinGhbAdMS@aspire.rjw.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1266 Lines: 28 On 11/07/17 15:59, Rafael J. Wysocki wrote: > On Tuesday, July 11, 2017 04:06:01 PM Dietmar Eggemann wrote: >> On 11/07/17 07:01, Viresh Kumar wrote: >>> On 10-07-17, 13:02, Dietmar Eggemann wrote: >>>> Yes, I will change this. The #define approach is not really necessary >>>> here since we're not in the scheduler hot-path and inlining is not >>>> really required here. >>> >>> It would be part of scheduler hot-path for the fast-switching case, isn't it ? >>> (I am not arguing against using weak functions, just wanted to correct above >>> statement). >> >> Yes you're right here. >> >> But in the meantime we're convinced that cpufreq_driver_fast_switch() is >> not the right place to call arch_set_freq_scale() since for (future) >> arm/arm64 fast-switch driver, the return value of >> cpufreq_driver->fast_switch() does not give us the information that the >> frequency value did actually change. >> >> So we probably have to do this soemwhere in the cpufreq driver(s) to >> support fast-switching until we have aperf/mperf like counters. > > If that's the case, I'd say call arch_set_freq_scale() from drivers in all > cases or it will get *really* confusing. Agreed, we should do it for slow-switching drivers from within the driver as well in this case.