From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763514AbYEHOlo (ORCPT ); Thu, 8 May 2008 10:41:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755117AbYEHOlc (ORCPT ); Thu, 8 May 2008 10:41:32 -0400 Received: from mtagate2.uk.ibm.com ([195.212.29.135]:31205 "EHLO mtagate2.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754701AbYEHOlb (ORCPT ); Thu, 8 May 2008 10:41:31 -0400 From: Christian Borntraeger To: Jeremy Fitzhardinge Subject: Re: [PATCH/RFC] stop_machine: make stop_machine_run more virtualization friendly Date: Thu, 8 May 2008 16:41:20 +0200 User-Agent: KMail/1.9.9 Cc: Rusty Russell , kvm-devel@lists.sourceforge.net, Ingo Molnar , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org References: <200805081520.38310.borntraeger@de.ibm.com> <48230137.9090705@goop.org> In-Reply-To: <48230137.9090705@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200805081641.20572.borntraeger@de.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Donnerstag, 8. Mai 2008 schrieb Jeremy Fitzhardinge: > Christian Borntraeger wrote: > > On kvm I have seen some rare hangs in stop_machine when I used more guest > > cpus than hosts cpus. e.g. 32 guest cpus on 1 host cpu triggered the > > hang quite often. I could also reproduce the problem on a 4 way z/VM host with > > a 64 way guest. > > > > I think that's one of those "don't do that then" cases ;) I really like 64 guest cpus as a good testcase for all kind of things. > > I think x86 (at least) is now using ticket locks, which is fair. Which > kernel are you seeing this problem on? Sorry, forgot to mention. Its kvm.git from 2 days ago on s390.