From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752155Ab2FKIrv (ORCPT ); Mon, 11 Jun 2012 04:47:51 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:56798 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750825Ab2FKIru (ORCPT ); Mon, 11 Jun 2012 04:47:50 -0400 Date: Mon, 11 Jun 2012 10:47:44 +0200 From: Ingo Molnar To: akpm@linux-foundation.org, dzickus@redhat.com Cc: mm-commits@vger.kernel.org, dzickus@redhat.com, joe@perches.com, mingo@elte.hu, nzimmer@sgi.com, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: + nmi-watchdog-quiet-down-the-boot-messages.patch added to -mm tree Message-ID: <20120611084744.GH31556@gmail.com> References: <20120608213709.B320BA022F@akpm.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120608213709.B320BA022F@akpm.mtv.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * akpm@linux-foundation.org wrote: > From: Don Zickus > Subject: nmi watchdog: quiet down the boot messages > > A bunch of bugzillas have complained how noisy the nmi_watchdog is during > boot-up especially with its expected failure cases (like virt and bios > resource contention). > > This is my attempt to quiet them down and keep it less confusing for the > end user. What I did is print the message for cpu0 and save it for future > comparisons. If future cpus have an identical message as cpu0, then don't > print the redundant info. However, if a future cpu has a different > message, happily print that loudly. > > Before the change, you would see something like: > > ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 > CPU0: Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz stepping 0a > Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver. > ... version: 2 > ... bit width: 40 > ... generic registers: 2 > ... value mask: 000000ffffffffff > ... max period: 000000007fffffff > ... fixed-purpose events: 3 > ... event mask: 0000000700000003 > NMI watchdog enabled, takes one hw-pmu counter. > Booting Node 0, Processors #1 > NMI watchdog enabled, takes one hw-pmu counter. > #2 > NMI watchdog enabled, takes one hw-pmu counter. > #3 Ok. > NMI watchdog enabled, takes one hw-pmu counter. > Brought up 4 CPUs > Total of 4 processors activated (22607.24 BogoMIPS). the problem really was that it didn't print which CPU it referred to - it just repeated the same message over and over again. If it said: NMI watchdog enabled on CPU#0, takes one hw-pmu counter. it would be far less confusing. This: > After the change, it is simplified to: > > ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 > CPU0: Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz stepping 0a > Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver. > ... version: 2 > ... bit width: 40 > ... generic registers: 2 > ... value mask: 000000ffffffffff > ... max period: 000000007fffffff > ... fixed-purpose events: 3 > ... event mask: 0000000700000003 > NMI watchdog enabled, takes one hw-pmu counter. > Booting Node 0, Processors #1 #2 #3 Ok. > Brought up 4 CPUs Is fine too but should be clarified to something like: NMI watchdog enabled on all CPUs, permanently consumes one hw-PMU counter (Please note the capitalization of 'PMU' as well.) Thanks, Ingo