From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53860) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQI9f-0004Qg-Lv for qemu-devel@nongnu.org; Thu, 11 Apr 2013 10:07:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UQI9a-00081A-G0 for qemu-devel@nongnu.org; Thu, 11 Apr 2013 10:07:11 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:49668) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQI9a-000810-C9 for qemu-devel@nongnu.org; Thu, 11 Apr 2013 10:07:06 -0400 Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 11 Apr 2013 10:07:05 -0400 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id 97E1938C8056 for ; Thu, 11 Apr 2013 10:06:59 -0400 (EDT) Received: from d01av05.pok.ibm.com (d01av05.pok.ibm.com [9.56.224.195]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r3BE6x56306448 for ; Thu, 11 Apr 2013 10:06:59 -0400 Received: from d01av05.pok.ibm.com (loopback [127.0.0.1]) by d01av05.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r3BE6wrk008371 for ; Thu, 11 Apr 2013 10:06:58 -0400 Message-ID: <5166C381.4030405@linux.vnet.ibm.com> Date: Thu, 11 Apr 2013 10:06:57 -0400 From: "Michael R. Hines" MIME-Version: 1.0 References: <1365632901-15470-1-git-send-email-mrhines@linux.vnet.ibm.com> <1365632901-15470-11-git-send-email-mrhines@linux.vnet.ibm.com> <20130411073843.GB19601@redhat.com> <51667FEE.903@redhat.com> <20130411111329.GA21714@redhat.com> <5166B86F.1050504@linux.vnet.ibm.com> <20130411135121.GB24942@redhat.com> In-Reply-To: <20130411135121.GB24942@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH RDMA support v1: 10/13] introduce new command migrate_check_for_zero List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org, owasserm@redhat.com, abali@us.ibm.com, mrhines@us.ibm.com, gokul@us.ibm.com, Paolo Bonzini On 04/11/2013 09:51 AM, Michael S. Tsirkin wrote: > On Thu, Apr 11, 2013 at 09:19:43AM -0400, Michael R. Hines wrote: >> On 04/11/2013 07:13 AM, Michael S. Tsirkin wrote: >>> On Thu, Apr 11, 2013 at 11:18:38AM +0200, Paolo Bonzini wrote: >>>> Il 11/04/2013 09:38, Michael S. Tsirkin ha scritto: >>>>> On Wed, Apr 10, 2013 at 06:28:18PM -0400, mrhines@linux.vnet.ibm.com wrote: >>>>>> From: "Michael R. Hines" >>>>>> >>>>>> This allows the user to disable zero page checking during migration >>>>>> >>>>>> Signed-off-by: Michael R. Hines >>>>> IMO this knob is too low level to expose to management. >>>>> Why not disable this automatically when migrating with rdma? >>>> Thinking more about it, I'm not sure why it is important to disable it. >>> This just illustrates the point. There's no place for such low level >>> knobs in the management interface. >>> >> I disagree with that: We already have precedent for this in the >> XBZRLE capability. > My understanding is the issue is protocol compatibility, > not optimization. E.g. you can migrate to file, for each > new feature you need a way to disable it to stay compatible. Ok, understood. I would be happy to add a check for the other migration URI protocols (like 'unix', 'tcp', etc) which says rejects disabling the zero page checking only if the URI is for rdma. Would that be OK?