From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757430Ab0GHNgX (ORCPT ); Thu, 8 Jul 2010 09:36:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756838Ab0GHNgU (ORCPT ); Thu, 8 Jul 2010 09:36:20 -0400 Date: Thu, 8 Jul 2010 16:35:42 +0300 From: Gleb Natapov To: Rik van Riel Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, avi@redhat.com, mingo@elte.hu, a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com, cl@linux-foundation.org, mtosatti@redhat.com Subject: Re: [PATCH v4 11/12] Let host know whether the guest can handle async PF in non-userspace context. Message-ID: <20100708133542.GX4689@redhat.com> References: <1278433500-29884-1-git-send-email-gleb@redhat.com> <1278433500-29884-12-git-send-email-gleb@redhat.com> <4C3553E2.7020607@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C3553E2.7020607@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 08, 2010 at 12:28:18AM -0400, Rik van Riel wrote: > On 07/06/2010 12:24 PM, Gleb Natapov wrote: > >If guest can detect that it runs in non-preemptable context it can > >handle async PFs at any time, so let host know that it can send async > >PF even if guest cpu is not in userspace. > > The code looks correct. One question though - is there a > reason to implement the userspace-only async PF path at > all, since the handling of async PF in non-userspace context > is introduced simultaneously? > Guest userspace-only async PF handling is added in patch 4 and non-userspace is added in patch 10. It is done for easy reviewing. If I implement everything in one patch it will be harder to see why things are done the way they are IMHO. -- Gleb.