From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757589Ab0LBQPR (ORCPT ); Thu, 2 Dec 2010 11:15:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45148 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757073Ab0LBQPP (ORCPT ); Thu, 2 Dec 2010 11:15:15 -0500 Date: Thu, 2 Dec 2010 11:15:02 -0500 From: Don Zickus To: Peter Zijlstra Cc: "Eric W. Biederman" , Vivek Goyal , Yinghai Lu , Ingo Molnar , Jason Wessel , "linux-kernel@vger.kernel.org" , Haren Myneni Subject: Re: perf hw in kexeced kernel broken in tip Message-ID: <20101202161502.GL18100@redhat.com> References: <1291219906.32004.1671.camel@laptop> <20101201162335.GB2511@redhat.com> <1291232292.32004.1969.camel@laptop> <20101201194644.GD2511@redhat.com> <1291232989.32004.1987.camel@laptop> <20101201195835.GE2511@redhat.com> <1291234036.32004.2008.camel@laptop> <20101202052321.GH18100@redhat.com> <1291275270.4023.20.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1291275270.4023.20.camel@twins> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 02, 2010 at 08:34:30AM +0100, Peter Zijlstra wrote: > On Thu, 2010-12-02 at 00:23 -0500, Don Zickus wrote: > > On Wed, Dec 01, 2010 at 01:48:07PM -0800, Eric W. Biederman wrote: > > > > > > > > Oh, but I'm not a device or sysdev thing, I'll never get something like > > > > that. > > > > > > There is also the reboot notifier, if the NMI needs to be controlled > > > outside of device model. Sigh. The NMI handling is such a special case. > > > > I tried reboot notifiers with the nmi_watchdog and acheived some success > > (on a Westmere box, a P4 still failed). Kdump is still screwed, but maybe > > we don't care for now. > > > > Here is the quick and dirty patch I used. > > > We'd really want a perf_event.c callback there to do as the hot-unplug > code does and detach all running counters from the cpu. Ok, I moved the reboot notifier stuff from kernel/watchdog.c to kernel/perf_event.c. Things still worked fine from a kexec perspective. Vivek suggested to me this morning that I should just blantantly disable the perf counter during init when running my test. Looking through the code I don't think I can do this using disable_all because some routines look for the active bit to be set and some arches have different disable registers than others. Thoughts? Cheers, Don