From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:40067) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIPmw-0000S9-5L for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:39:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UIPms-00028l-Cl for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:39:10 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:49477) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIPms-00028T-8w for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:39:06 -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 ; Wed, 20 Mar 2013 16:39:05 -0400 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id 4D072C90052 for ; Wed, 20 Mar 2013 16:39:02 -0400 (EDT) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r2KKd1Dg272758 for ; Wed, 20 Mar 2013 16:39:01 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r2KKd15g021015 for ; Wed, 20 Mar 2013 17:39:01 -0300 Message-ID: <514A1E64.50404@linux.vnet.ibm.com> Date: Wed, 20 Mar 2013 16:39:00 -0400 From: "Michael R. Hines" MIME-Version: 1.0 References: <51489BC3.3030504@linux.vnet.ibm.com> <51489D05.2000400@redhat.com> <5148A2F6.1070206@linux.vnet.ibm.com> <5148A5FB.1000209@redhat.com> <20130320130754.GA9777@redhat.com> <5149D2A4.2070106@linux.vnet.ibm.com> <20130320155514.GA20701@redhat.com> <5149DF08.4090209@linux.vnet.ibm.com> <20130320190633.GB22631@redhat.com> <514A19F6.3020406@linux.vnet.ibm.com> <20130320203119.GA23583@redhat.com> In-Reply-To: <20130320203119.GA23583@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH RDMA support v4: 03/10] more verbose documentation of the RDMA transport 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 Agreed. Very useful for KSM. Unmapped virtual addresses cannot be pinned for RDMA (the hardware will break), but there's no way to know they are unmapped without checking another data structure. - Michael On 03/20/2013 04:31 PM, Michael S. Tsirkin wrote: > > OK sure, this could be useful to detect pages deduplicated by KSM and only > transmit one copy. There's still the question of creating same > duplicate mappings on destination - do you just do data copy on destination? > > Not sure why you talk about unmapped pages above though, it seems > not really relevant... > > There's also the matter of KSM not touching pinned pages, > that's another good reason not to pin all pages on destination, > they won't be deduplicated. >