From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752658AbaLSOv2 (ORCPT ); Fri, 19 Dec 2014 09:51:28 -0500 Received: from service87.mimecast.com ([91.220.42.44]:41242 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752284AbaLSOv1 convert rfc822-to-8bit (ORCPT ); Fri, 19 Dec 2014 09:51:27 -0500 Message-ID: <54943B6A.9050309@arm.com> Date: Fri, 19 Dec 2014 15:51:22 +0100 From: Dietmar Eggemann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Fengguang Wu CC: Michael Turquette , LKP , "linux-kernel@vger.kernel.org" Subject: Re: [sched] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/cpu/common.c:1439 warn_pre_alternatives() References: <20141210232645.GD24163@wfg-t540p.sh.intel.com> In-Reply-To: <20141210232645.GD24163@wfg-t540p.sh.intel.com> X-OriginalArrivalTime: 19 Dec 2014 14:51:24.0268 (UTC) FILETIME=[427662C0:01D01B9B] X-MC-Unique: 114121914512405301 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Fengguang, On 11/12/14 00:26, Fengguang Wu wrote: > Hi Dietmar, > > FYI, here is another bisect result. thanks for testing this on another arch then ARM! The problem is that the weak arch_scale_cpu_capacity calls default_scale_cpu_capacity on a system which doesn't overwrite it and the default one accesses the sched_domain which is not allocated that early when called by scheduler_tick. I only tested it on an ARM system which in this tree which overwrites arch_scale_cpu_capacity and does not access sched_domain. Have to look into it and will test the default case from now on too. -- Dietmar > > https://git.linaro.org/people/mturquette/linux.git eas-next > commit 1fadb581b0be9420b143e43ff2f4a07ea7e45f6c > Author: Dietmar Eggemann > AuthorDate: Tue Dec 2 14:06:24 2014 +0000 > Commit: Michael Turquette > CommitDate: Tue Dec 9 20:33:17 2014 -0800 > > sched: Make usage and load tracking cpu scale-invariant > > Besides the existing frequency scale-invariance correction factor, apply > cpu scale-invariance correction factor to usage and load tracking. > > Cpu scale-invariance takes cpu performance deviations due to > micro-architectural differences (i.e. instructions per seconds) between > cpus in HMP systems (e.g. big.LITTLE) and differences in the frequency > value of the highest OPP between cpus in SMP systems into consideration. > > Each segment of the sched_avg::{running_avg_sum, runnable_avg_sum} > geometric series is now scaled by the cpu performance factor too so the > sched_avg::{utilization_avg_contrib, load_avg_contrib} of each entity will > be invariant from the particular cpu of the HMP/SMP system it is gathered > on. As a result, cfs_rq::runnable_load_avg which is the sum of > sched_avg::load_avg_contrib, becomes cpu scale-invariant too. > > So the {usage, load} level that is returned by {get_cpu_usage, > weighted_cpuload} stays relative to the max cpu performance of the system. > > Cc: Ingo Molnar > Cc: Peter Zijlstra > Signed-off-by: Dietmar Eggemann > [...]