From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36324) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIPYo-0002Lb-02 for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:24:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UIPYl-0005OG-KB for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:24:33 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:48000) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UIPYl-0005OA-D6 for qemu-devel@nongnu.org; Wed, 20 Mar 2013 16:24:31 -0400 Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 20 Mar 2013 14:24:29 -0600 Received: from d01relay07.pok.ibm.com (d01relay07.pok.ibm.com [9.56.227.147]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id 5FD4B38C8051 for ; Wed, 20 Mar 2013 16:24:21 -0400 (EDT) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay07.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r2KKOJ4R53477376 for ; Wed, 20 Mar 2013 16:24:19 -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 r2KKOI3A010986 for ; Wed, 20 Mar 2013 17:24:18 -0300 Message-ID: <514A1AEE.1070308@linux.vnet.ibm.com> Date: Wed, 20 Mar 2013 16:24:14 -0400 From: "Michael R. Hines" MIME-Version: 1.0 References: <51487F68.2060305@linux.vnet.ibm.com> <20130319151606.GA13649@redhat.com> <51488521.4010909@linux.vnet.ibm.com> <20130319153658.GA14317@redhat.com> <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> In-Reply-To: <20130320155514.GA20701@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 On 03/20/2013 11:55 AM, Michael S. Tsirkin wrote: > Then, later, in a separate patch, I can implement /dev/pagemap support. > > When that's done, RDMA dynamic registration will actually take effect and > benefit from actually verifying that the page is mapped or not. > > - Michael > Mapped into guest? You mean e.g. for ballooning? > Three scenarios are candidates for mapped checking: 1. anytime the virtual machine has not yet accessed a page (usually during the 1st-time boot) 2. Anytime madvise(DONTNEED) happens (for ballooning) 3. Anytime cgroups kicks out a zero page that was accessed and faulted but not dirty that is a clean candidate for unmapping. (I did a test that seems to confirm that cgroups is pretty "smart" about that) Basically, anytime the pagemap says "this page is *not* swap and *not* mapped - then the page is not important during the 1st iteration. On the subsequent iterations, we come along as normal checking the dirty bitmap as usual. - Michael