From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423188AbXDXWiB (ORCPT ); Tue, 24 Apr 2007 18:38:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423195AbXDXWiA (ORCPT ); Tue, 24 Apr 2007 18:38:00 -0400 Received: from mx1.redhat.com ([66.187.233.31]:59632 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423188AbXDXWh7 (ORCPT ); Tue, 24 Apr 2007 18:37:59 -0400 Message-ID: <462E86BF.7010402@redhat.com> Date: Tue, 24 Apr 2007 18:37:51 -0400 From: Chris Snook User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: LAPLACE Cyprien CC: virtualization@lists.linux-foundation.org, Linux Kernel , Jeremy Fitzhardinge Subject: Re: SMP lockup in virtualized environment References: <462E4223.1050109@trango-systems.com> In-Reply-To: <462E4223.1050109@trango-systems.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org LAPLACE Cyprien wrote: > An example: in kernel/pid.c:alloc_pid(), if one of the guest CPUs is > descheduled when holding the pidmap_lock, what happens to the other > guest CPUs who want to alloc/free pids ? Are they blocked too ? Yup. This is where it's really nice to have directed yields, where you tell the hypervisor to give your physical CPU time to the vcpu that's holding the lock you're blocking on. I know s390 can do this. Perhaps it's something worth generalizing in paravirt_ops? -- Chris