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 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 95440C433E1 for ; Thu, 6 Aug 2020 17:08:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EDE2D23119 for ; Thu, 6 Aug 2020 17:08:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730047AbgHFRHc (ORCPT ); Thu, 6 Aug 2020 13:07:32 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:63876 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729728AbgHFRGl (ORCPT ); Thu, 6 Aug 2020 13:06:41 -0400 Received: from 89-64-86-116.dynamic.chello.pl (89.64.86.116) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.415) id a0952d0a893f35a5; Thu, 6 Aug 2020 13:39:54 +0200 From: "Rafael J. Wysocki" To: Doug Smythies Cc: "'Rafael J. Wysocki'" , 'Linux Documentation' , 'LKML' , 'Peter Zijlstra' , 'Srinivas Pandruvada' , 'Giovanni Gherdovich' , 'Francisco Jerez' , 'Linux PM' Subject: Re: [PATCH] cpufreq: intel_pstate: Implement passive mode with HWP enabled Date: Thu, 06 Aug 2020 13:39:53 +0200 Message-ID: <5275102.Ez0hqPNOlg@kreacher> In-Reply-To: <004601d66bb6$199ce1a0$4cd6a4e0$@net> References: <3955470.QvD6XneCf3@kreacher> <2418846.A4mPlhI7ni@kreacher> <004601d66bb6$199ce1a0$4cd6a4e0$@net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thursday, August 6, 2020 7:54:47 AM CEST Doug Smythies wrote: > On 2020.08.03 10:09 Rafael J. Wysocki wrote: > > On Sunday, August 2, 2020 5:17:39 PM CEST Doug Smythies wrote: > > > On 2020.07.19 04:43 Rafael J. Wysocki wrote: > > > > On Fri, Jul 17, 2020 at 3:37 PM Doug Smythies wrote: > > > > > On 2020.07.16 05:08 Rafael J. Wysocki wrote: > > > > > > On Wed, Jul 15, 2020 at 10:39 PM Doug Smythies wrote: > > > > > >> On 2020.07.14 11:16 Rafael J. Wysocki wrote: > > > > > >> > > > > > > >> > From: Rafael J. Wysocki > > > > > >> ... > > > > > >> > Since the passive mode hasn't worked with HWP at all, and it is not going to > > > > > >> > the default for HWP systems anyway, I don't see any drawbacks related to making > > > > > >> > this change, so I would consider this as 5.9 material unless there are any > > > > > >> > serious objections. > > > > > >> > > > > > >> Good point. > > > > > > > > > > Actually, for those users that default to passive mode upon boot, > > > > > this would mean they would find themselves using this. > > > > > Also, it isn't obvious, from the typical "what driver and what governor" > > > > > inquiry. > > > > > > > > So the change in behavior is that after this patch > > > > intel_pstate=passive doesn't imply no_hwp any more. > > > > > > > > That's a very minor difference though and I'm not aware of any adverse > > > > effects it can cause on HWP systems anyway. > > > > > > My point was, that it will now default to something where > > > testing has not been completed. > > > > > > > The "what governor" is straightforward in the passive mode: that's > > > > whatever cpufreq governor has been selected. > > > > > > I think you might have missed my point. > > > From the normal methods of inquiry one does not know > > > if HWP is being used or not. Why? Because with > > > or without HWP one gets the same answers under: > > > > > > /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver > > > /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor > > > > Yes, but this is also the case in the active mode, isn't it? > > Yes, fair enough. > But we aren't changing what it means by default > between kernel 5.8 and 5.9-rc1. No, we aren't. The only (expected) change is when booting with intel_pstate=passive and without intel_pstate=no_hwp in the command line. Which should be easy enough to address by adding intel_pstate=no_hwp to the command line in 5.9-rc1 and later (to achieve the same behavior after a fresh boot). Cheers!