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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EFF3C433F5 for ; Wed, 17 Nov 2021 15:08:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC31A61B4C for ; Wed, 17 Nov 2021 15:08:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232168AbhKQPLJ (ORCPT ); Wed, 17 Nov 2021 10:11:09 -0500 Received: from foss.arm.com ([217.140.110.172]:58506 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231697AbhKQPLH (ORCPT ); Wed, 17 Nov 2021 10:11:07 -0500 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 6CFBE1FB; Wed, 17 Nov 2021 07:08:08 -0800 (PST) Received: from [10.57.24.78] (unknown [10.57.24.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BAD593F5A1; Wed, 17 Nov 2021 07:08:06 -0800 (PST) Subject: Re: [PATCH] base: arch_topology: Use policy->max to calculate freq_factor To: "Rafael J. Wysocki" Cc: Thara Gopinath , Sudeep Holla , Greg Kroah-Hartman , Bjorn Andersson , Linux Kernel Mailing List , linux-arm-msm References: <20211115201010.68567-1-thara.gopinath@linaro.org> <8f7397e3-4e92-c84d-9168-087967f4d683@arm.com> From: Lukasz Luba Message-ID: <7f077790-da4c-35b8-0eea-cbdc630f9d2a@arm.com> Date: Wed, 17 Nov 2021 15:08:04 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/17/21 12:49 PM, Rafael J. Wysocki wrote: > On Wed, Nov 17, 2021 at 11:46 AM Lukasz Luba wrote: >> >> Hi Rafael, >> >> On 11/16/21 7:05 PM, Rafael J. Wysocki wrote: >>> On Mon, Nov 15, 2021 at 9:10 PM Thara Gopinath >>> wrote: >>>> >>>> cpuinfo.max_freq can reflect boost frequency if enabled during boot. Since >>>> we don't consider boost frequencies while calculating cpu capacities, use >>>> policy->max to populate the freq_factor during boot up. >>> >>> I'm not sure about this. schedutil uses cpuinfo.max_freq as the max frequency. >> >> Agree it's tricky how we treat the boost frequencies and also combine >> them with thermal pressure. >> We probably would have consider these design bits: >> 1. Should thermal pressure include boost frequency? > > Well, I guess so. > > Running at a boost frequency certainly increases thermal pressure. > >> 2. Should max capacity 1024 be a boost frequency so scheduler >> would see it explicitly? > > That's what it is now if cpuinfo.max_freq is a boost frequency. > >> - if no, then schedutil could still request boost freq thanks to >> map_util_perf() where we add 25% to the util and then >> map_util_freq() would return a boost freq when util was > 1024 >> >> >> I can see in schedutil only one place when cpuinfo.max_freq is used: >> get_next_freq(). If the value stored in there is a boost, >> then don't we get a higher freq value for the same util? > > Yes. we do, which basically is my point. > > The schedutil's response is proportional to cpuinfo.max_freq and that > needs to be taken into account for the results to be consistent. > This boost thing wasn't an issue for us, because we didn't have platforms which come with it (till recently). I've checked that you have quite a few CPUs which support huge boost freq, e.g. 5GHz vs. 3.6GHz nominal max freq [1]. Am I reading this correctly as kernel boost freq? Do you represent this 5GHz as 1024 capacity? From this schedutil get_next_freq() I would guess yes. I cannot find if you use thermal pressure, could you help me with this, please? [1] https://ark.intel.com/content/www/us/en/ark/products/186605/intel-core-i99900k-processor-16m-cache-up-to-5-00-ghz.html