From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932341Ab1GEMYV (ORCPT ); Tue, 5 Jul 2011 08:24:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10072 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932068Ab1GEMYU (ORCPT ); Tue, 5 Jul 2011 08:24:20 -0400 Date: Tue, 5 Jul 2011 08:24:05 -0400 From: Don Zickus To: Ingo Molnar Cc: Cyrill Gorcunov , Stephane Eranian , Lin Ming , Peter Zijlstra , Arnaldo Carvalho de Melo , Frederic Weisbecker , LKML Subject: Re: [PATCH -tip, final] perf, x86: Add hw_watchdog_set_attr() in a sake of nmi-watchdog on P4 Message-ID: <20110705122405.GU3765@redhat.com> References: <20110705100320.GK17941@sun> <20110705102017.GA12458@elte.hu> <20110705103403.GN17941@sun> <20110705105959.GA14435@elte.hu> <20110705110550.GQ17941@sun> <20110705112002.GA15654@elte.hu> <20110705113620.GS17941@sun> <20110705114437.GC15654@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110705114437.GC15654@elte.hu> 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 On Tue, Jul 05, 2011 at 01:44:37PM +0200, Ingo Molnar wrote: > > Probably I miss something and you mean something completely different? > > What i am missing is that you have not pointed out the *core problem* > you are fixing and it's not obvious from the changelog either! Cyril, I think you didn't explain the fact that without this patch if you enable nmi_watchdog, then the 'perf' tool doesn't work on a P4. This is bad for end users. It seems like with all the P4 register coupling an end user can run either the nmi_watchdog _or_ perf but not both. For RHEL-6 this was bad because we like to enable the nmi_watchdog. This patch does some magic and allows the end user to use the nmi_watchdog _and_ perf concurrently (a common expected behaviour). I hope that clears things up Ingo. Cheers, Don