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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 33CACC35247 for ; Mon, 3 Feb 2020 15:56:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0565E20838 for ; Mon, 3 Feb 2020 15:56:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RiurZ3h3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728404AbgBCP4N (ORCPT ); Mon, 3 Feb 2020 10:56:13 -0500 Received: from merlin.infradead.org ([205.233.59.134]:52716 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726836AbgBCP4N (ORCPT ); Mon, 3 Feb 2020 10:56:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IZ+2IhtH9Wkn/JPrwSM2mpEcPwZEZbOVR1hOCann57s=; b=RiurZ3h3eS5nuMtjXg5FMdIjhR coQQnqM3nX7kE6gUYmY5LRk5Fo8cGcPIV4FhaPrYcmTHwCcAGZvug0BbyINskEAdjbyQoaLmPZHX5 Yad/7eRL19t07CTL9oISrxVFaEYyDO4NSeUfgEeuZkYgXoj+zERvXQUeCZ5hawAuyHjhelQRDPQQ9 Ym1aGZVXiUksWi9GYOqxFhtlzO7DUTxr+ocW15tXfr6V1nCCZAX9lpVOgM1k2MJa/dSMGi29vrZ5c Kt205eOeDJltdnRbOqY7OJXQbsc74smcRS7g7y4QYBqmoaulkealVDcqbaJBMtOCTGjy/eQ/VfeUT ZTbDiYQg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iye4l-0007B1-Dv; Mon, 03 Feb 2020 15:55:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 8C67B30220B; Mon, 3 Feb 2020 16:54:04 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id ABC182B6E6441; Mon, 3 Feb 2020 16:55:49 +0100 (CET) Date: Mon, 3 Feb 2020 16:55:49 +0100 From: Peter Zijlstra To: Thara Gopinath Cc: Randy Dunlap , mingo@redhat.com, ionela.voinescu@arm.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rui.zhang@intel.com, qperret@google.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, rostedt@goodmis.org, will@kernel.org, catalin.marinas@arm.com, sudeep.holla@arm.com, juri.lelli@redhat.com, corbet@lwn.net, linux-kernel@vger.kernel.org, amit.kachhap@gmail.com, javi.merino@kernel.org, amit.kucheria@verdurent.com Subject: Re: [Patch v9 7/8] sched/fair: Enable tuning of decay period Message-ID: <20200203155549.GL14914@hirez.programming.kicks-ass.net> References: <1580250967-4386-1-git-send-email-thara.gopinath@linaro.org> <1580250967-4386-8-git-send-email-thara.gopinath@linaro.org> <4eb10687-1a62-cee3-7285-3f50cc023071@infradead.org> <5E380D1D.7020500@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5E380D1D.7020500@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 03, 2020 at 07:07:57AM -0500, Thara Gopinath wrote: > On 01/28/2020 06:56 PM, Randy Dunlap wrote: > > Hi, > > > > On 1/28/20 2:36 PM, Thara Gopinath wrote: > >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > >> index e35b28e..be4147b 100644 > >> --- a/Documentation/admin-guide/kernel-parameters.txt > >> +++ b/Documentation/admin-guide/kernel-parameters.txt > >> @@ -4376,6 +4376,11 @@ > >> incurs a small amount of overhead in the scheduler > >> but is useful for debugging and performance tuning. > >> > >> + sched_thermal_decay_shift= > >> + [KNL, SMP] Set decay shift for thermal pressure signal. > >> + Format: integer between 0 and 10 > >> + Default is 0. > >> + > > > > That tells an admin [or any reader] almost nothing about this kernel parameter > > or what it does. And nothing about what unit the value is in. > > Does the value 0 disable this feature? > > Thanks for the review. 0 does not disable "thermal pressure" feature. 0 > means the default decay period for averaging PELT signals (which is > usually 32 but configurable) will also be applied for thermal pressure > signal. A shift will shift the default decay period. > > You are right. It needs more explanation here. I will fix it and send v10. Or just send an update for this patch? I'm thinking most of this is looking good.