From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:38045) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQHPw-00032d-Bb for qemu-devel@nongnu.org; Thu, 11 Apr 2013 09:19:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UQHPp-0000ON-TI for qemu-devel@nongnu.org; Thu, 11 Apr 2013 09:19:56 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:50835) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQHPp-0000OG-P0 for qemu-devel@nongnu.org; Thu, 11 Apr 2013 09:19:49 -0400 Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 11 Apr 2013 09:19:48 -0400 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 7BA856E8041 for ; Thu, 11 Apr 2013 09:19:42 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r3BDJimC305472 for ; Thu, 11 Apr 2013 09:19:45 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r3BDJiBp015146 for ; Thu, 11 Apr 2013 09:19:44 -0400 Message-ID: <5166B86F.1050504@linux.vnet.ibm.com> Date: Thu, 11 Apr 2013 09:19:43 -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> In-Reply-To: <20130411111329.GA21714@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 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. Zero page checking is no "more" low-level than this capability already is and the community has already agreed to expose this capability to management. Since zero page scanning does in fact affect performance, we not give the user the option? Why would the community agree to expose one low-level feature and not expose another? - Michael