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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 3FD16C433DF for ; Tue, 11 Aug 2020 15:33:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0D3B20768 for ; Tue, 11 Aug 2020 15:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728883AbgHKPdx (ORCPT ); Tue, 11 Aug 2020 11:33:53 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:62204 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728859AbgHKPdw (ORCPT ); Tue, 11 Aug 2020 11:33:52 -0400 Received: from 89-64-89-44.dynamic.chello.pl (89.64.89.44) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.415) id 2461079d11a94e2c; Tue, 11 Aug 2020 17:33:50 +0200 From: "Rafael J. Wysocki" To: Francisco Jerez Cc: Linux PM , Linux Documentation , LKML , Peter Zijlstra , Srinivas Pandruvada , Giovanni Gherdovich , Doug Smythies , Viresh Kumar Subject: Re: [PATCH v7] cpufreq: intel_pstate: Implement passive mode with HWP enabled Date: Tue, 11 Aug 2020 17:33:49 +0200 Message-ID: <4931766.VNY61sLD3B@kreacher> In-Reply-To: <87mu32atsy.fsf@riseup.net> References: <4981405.3kqTVLv5tO@kreacher> <122847018.uQ7iJ9lzrg@kreacher> <87mu32atsy.fsf@riseup.net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tuesday, August 11, 2020 2:51:41 AM CEST Francisco Jerez wrote: > > --==-=-= > Content-Type: multipart/mixed; boundary="=-=-=" > > --=-=-= > Content-Type: text/plain; charset=utf-8 > Content-Disposition: inline > Content-Transfer-Encoding: quoted-printable > > "Rafael J. Wysocki" writes: > > > From: Rafael J. Wysocki > > > > Allow intel_pstate to work in the passive mode with HWP enabled and > > make it set the HWP minimum performance limit (HWP floor) to the > > P-state value given by the target frequency supplied by the cpufreq > > governor, so as to prevent the HWP algorithm and the CPU scheduler > > from working against each other, at least when the schedutil governor > > is in use, and update the intel_pstate documentation accordingly. > > > > Among other things, this allows utilization clamps to be taken > > into account, at least to a certain extent, when intel_pstate is > > in use and makes it more likely that sufficient capacity for > > deadline tasks will be provided. > > > > After this change, the resulting behavior of an HWP system with > > intel_pstate in the passive mode should be close to the behavior > > of the analogous non-HWP system with intel_pstate in the passive > > mode, except that in the frequency range below the base frequency > > (ie. the frequency retured by the base_frequency cpufreq attribute > > in sysfs on HWP systems) the HWP algorithm is allowed to make the > > CPU run at a frequency above the floor P-state set by intel_pstate, > > with or without hardware coordination of P-states among CPUs in the > > same package. > > > > The "frequency range below the base frequency" part of the paragraph > above seems somewhat misleading, since AFAICT the same thing will happen > in the P-state range above the base frequency. Fair enough. I rephrased the changelog when applying the patch. > Another minor comment below, other than that LGTM: And this one has been fixed too. > Reviewed-by: Francisco Jerez Thanks!