From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754625Ab1HRApF (ORCPT ); Wed, 17 Aug 2011 20:45:05 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:43118 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754190Ab1HRApC (ORCPT ); Wed, 17 Aug 2011 20:45:02 -0400 Date: Wed, 17 Aug 2011 17:44:59 -0700 From: "Paul E. McKenney" To: Avi Kivity 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 Message-ID: <20110818004459.GQ2419@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com 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> <4E4C5CBE.5040102@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E4C5CBE.5040102@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 17, 2011 at 05:28:46PM -0700, Avi Kivity wrote: > 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 Very good, thank you both for bearing with me on this! Thanx, Paul