From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752890Ab1HRA2v (ORCPT ); Wed, 17 Aug 2011 20:28:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25848 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513Ab1HRA2u (ORCPT ); Wed, 17 Aug 2011 20:28:50 -0400 Message-ID: <4E4C5CBE.5040102@redhat.com> Date: Wed, 17 Aug 2011 17:28:46 -0700 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110707 Thunderbird/5.0 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Gleb Natapov , linux-kernel@vger.kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org Subject: Re: RCU treating guest mode just like it does user-mode execution References: <20110817204327.GA10633@linux.vnet.ibm.com> <20110817215015.GA6423@redhat.com> <20110817220520.GN2419@linux.vnet.ibm.com> <20110817235529.GA8163@redhat.com> <20110818002513.GP2419@linux.vnet.ibm.com> In-Reply-To: <20110818002513.GP2419@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/17/2011 05:25 PM, Paul E. McKenney wrote: > > > > > Wouldn't scheduling-clock interrupt kick vcpu out of a guest mode much > > earlier then 30 seconds? > > The scheduling-clock interrupt would happen, but I do not know whether > or not it would kick the vcpu out of guest mode in such a way that > would result in RCU thinking that the CPU has passed through a quiescent > state. > The result can only be one of reenter guest (and rcu_virt_note_context_switch) schedule() exit to userspace -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.