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=-2.3 required=3.0 tests=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 84D4BC35254 for ; Wed, 5 Feb 2020 12:49:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F4CA20702 for ; Wed, 5 Feb 2020 12:49:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727068AbgBEMt5 (ORCPT ); Wed, 5 Feb 2020 07:49:57 -0500 Received: from foss.arm.com ([217.140.110.172]:46778 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726308AbgBEMt4 (ORCPT ); Wed, 5 Feb 2020 07:49:56 -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 057631FB; Wed, 5 Feb 2020 04:49:56 -0800 (PST) Received: from [10.37.12.130] (unknown [10.37.12.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3DB2D3F52E; Wed, 5 Feb 2020 04:49:34 -0800 (PST) Subject: Re: [PATCH 3/3] ARM: exynos_defconfig: Enable Energy Model framework To: Krzysztof Kozlowski Cc: kgene@kernel.org, linux-arm-kernel@lists.infradead.org, "linux-samsung-soc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , devicetree@vger.kernel.org, linux-pm@vger.kernel.org, myungjoo.ham@samsung.com, kyungmin.park@samsung.com, Chanwoo Choi , robh+dt@kernel.org, mark.rutland@arm.com, =?UTF-8?Q?Bart=c5=82omiej_=c5=bbo=c5=82nierkiewicz?= , dietmar.eggemann@arm.com References: <20200127215453.15144-1-lukasz.luba@arm.com> <20200127215453.15144-4-lukasz.luba@arm.com> <20200131204118.GA27284@kozik-lap> From: Lukasz Luba Message-ID: Date: Wed, 5 Feb 2020 12:49:26 +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: <20200131204118.GA27284@kozik-lap> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Krzysztof, On 1/31/20 8:41 PM, Krzysztof Kozlowski wrote: > On Fri, Jan 31, 2020 at 05:30:46PM +0000, Lukasz Luba wrote: > >>> >>>> |-----------------------------------------------|--------------- >>>> | performance | SchedUtil | SchedUtil | performance >>>> | governor | governor | governor | governor >>>> | | w/o EAS | w/ EAS | >>>> ----------------|---------------|---------------|---------------|--------------- >>>> hackbench w/ PL | 12.7s | 11.7s | 12.0s | 13.0s - 12.2s >>>> hackbench w/o PL| 9.2s | 8.1s | 8.2s | 9.2s - 8.4s >>> >>> Why does the performance different before and after this patch? >> >> Probably due to better locality and cache utilization. I can see that >> there is ~700k context switches vs ~450k and ~160k migrations vs ~50k. >> If you need to communicate two threads in different clusters, it will go >> through CCI. > > Mhmm... I was not specific - I mean, "performance governor". All this > you mentioned should not differ between performance governor before and > after. However once you have 12.7, then 13.0 - 12.2. Unless multi-core > scheduler affects it... but then these numbers here are not showing > only this change, but also the SCHED_MC effect. In such case each of > commits should be coming with their own numbers. Agree, I should have not put 'this patch set' in the commit msg. It should go into the cover letter and avoid this confusion. You are right with ' Unless multi-core scheduler affects it...', that's why when the SCHED_MC is missing, the decisions about task placing might cause this variation and delay '13.0 - 12.2' seconds. > >> As mentioned in response to patch 1/3. The fist patch would create MC >> domain, something different than Energy Model or EAS. The decisions in >> the scheduler would be different. >> >> I can merge 1/3 and 3/3 if you like, though. > > I understand now that their independent. Still, they are part of one > goal to tune the scheduler for Exynos platform. Splitting these looks > too much, like enabling multiple drivers one after another. > > However if you provide numbers for each of cases (before patches, multi > core scheduler, energy model with DTS), then I see benefit of splitting > it. Each commit would have its own rationale. I am not sure if it is > worth such investigation - that's just defconfig... distros might ignore > it anyway. Good point, and I agree that it would require more investigation, for which unfortunately I don't have currently spare cycles. Should I merge patch 1/3 and 3/3 and send the v2 with a cover letter which would have the test results? Regards, Lukasz