Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754470Ab3GJKun (ORCPT ); Wed, 10 Jul 2013 06:50:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36905 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753974Ab3GJKum (ORCPT ); Wed, 10 Jul 2013 06:50:42 -0400 Date: Wed, 10 Jul 2013 13:48:43 +0300 From: Gleb Natapov To: Alexander Graf Cc: Christian Borntraeger , Dominik Dingel , Paolo Bonzini , Heiko Carstens , Martin Schwidefsky , Cornelia Huck , Xiantao Zhang , Christoffer Dall , Marc Zyngier , Ralf Baechle , kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] PF: Provide additional direct page notification Message-ID: <20130710104843.GS24941@redhat.com> References: <1373378207-10451-1-git-send-email-dingel@linux.vnet.ibm.com> <1373378207-10451-4-git-send-email-dingel@linux.vnet.ibm.com> <51DC33E7.1030404@de.ibm.com> <282EB214-206B-4A04-9830-D97679C9F4EC@suse.de> <20130710104253.GQ24941@redhat.com> <13B3500B-18A9-4B97-8C85-597BEAFC9250@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <13B3500B-18A9-4B97-8C85-597BEAFC9250@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1614 Lines: 40 On Wed, Jul 10, 2013 at 12:45:59PM +0200, Alexander Graf wrote: > > On 10.07.2013, at 12:42, Gleb Natapov wrote: > > > On Wed, Jul 10, 2013 at 12:39:01PM +0200, Alexander Graf wrote: > >> > >> On 09.07.2013, at 18:01, Christian Borntraeger wrote: > >> > >>> On 09/07/13 15:56, Dominik Dingel wrote: > >>>> By setting a Kconfig option, the architecture can control when > >>>> guest notifications will be presented by the apf backend. > >>>> So there is the default batch mechanism, working as before, where the vcpu thread > >>>> should pull in this information. On the other hand there is now the direct > >>>> mechanism, this will directly push the information to the guest. > >>>> > >>>> Still the vcpu thread should call check_completion to cleanup leftovers, > >>>> that leaves most of the common code untouched. > >>>> > >>>> Signed-off-by: Dominik Dingel > >>> > >>> Acked-by: Christian Borntraeger > >>> for the "why". We want to use the existing architectured interface. > >> > >> Shouldn't this be a runtime option? > >> > > Why? What is the advantage of using sync delivery when HW can do it > > async? > > What's the advantage of having an option at all then? Who selects it? > x86 is stupid and cannot deliver the even asynchronously. Platform that can do it select the option. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/