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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 667C5C43381 for ; Mon, 18 Feb 2019 22:04:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2524921479 for ; Mon, 18 Feb 2019 22:04:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731374AbfBRWEb (ORCPT ); Mon, 18 Feb 2019 17:04:31 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:42662 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729530AbfBRWE3 (ORCPT ); Mon, 18 Feb 2019 17:04:29 -0500 Received: from 79.184.254.15.ipv4.supernova.orange.pl (79.184.254.15) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.183) id 1f037ce711af676d; Mon, 18 Feb 2019 23:04:27 +0100 From: "Rafael J. Wysocki" To: Doug Smythies Cc: 'Linux PM' , 'Srinivas Pandruvada' , 'LKML' Subject: Re: [PATCH v2] cpufreq: intel_pstate: Rework iowait boosting to be less aggressive Date: Mon, 18 Feb 2019 23:03:03 +0100 Message-ID: <2407408.YatPz1rZtD@aspire.rjw.lan> In-Reply-To: <000c01d4c6f6$914a7f20$b3df7d60$@net> References: <2038590.kmssd2ZIyd@aspire.rjw.lan> <16144228.tcT5YVROcV@aspire.rjw.lan> <000c01d4c6f6$914a7f20$b3df7d60$@net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday, February 17, 2019 8:25:37 PM CET Doug Smythies wrote: > On 2019.02.07 03:51 Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > The current iowait boosting mechanism in intel_pstate_update_util() > > is quite aggressive, as it goes to the maximum P-state right away, > > and may cause excessive amounts of energy to be used, which is not > > desirable and arguably isn't necessary too. > > > > Follow commit a5a0809bc58e ("cpufreq: schedutil: Make iowait boost > > more energy efficient") that reworked the analogous iowait boost > > mechanism in the schedutil governor and make the iowait boosting > > in intel_pstate_update_util() work along the same lines. > > > > Signed-off-by: Rafael J. Wysocki > > --- > > > > -> v2: > > * Follow the Doug's suggestion and drop the immediate jump to > > max P-state if boost is max. The code is simpler this way and > > the perf impact should not be noticeable on average. > > Hi Rafael, > > Something has broken on my incoming e-mail sorting stuff, and I > missed this one (and some others). > > This V2 is not actually what I was proposing. I was O.K. with > the immediate jump, but I didn't want the set_pstate step > by-passed if it was already at max because that would also > by-pass the trace sample, if it was enabled. > > Anyway, this V2 seems O.K. to me. I tested it compared to V1 > and, as you mentioned, wasn't able to detect any energy consumption > or performance differences. Thanks for the confirmation!