From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:52137) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UPmi8-0004So-Bb for qemu-devel@nongnu.org; Wed, 10 Apr 2013 00:32:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UPmi6-0001qf-0D for qemu-devel@nongnu.org; Wed, 10 Apr 2013 00:32:40 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:41928) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UPmi5-0001qW-Qg for qemu-devel@nongnu.org; Wed, 10 Apr 2013 00:32:37 -0400 Received: from /spool/local by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 9 Apr 2013 22:32:36 -0600 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 31E8619D8036 for ; Tue, 9 Apr 2013 22:32:30 -0600 (MDT) Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r3A4WY00138972 for ; Tue, 9 Apr 2013 22:32:34 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r3A4WW1S000820 for ; Tue, 9 Apr 2013 22:32:33 -0600 Message-ID: <5164EB5F.80403@linux.vnet.ibm.com> Date: Wed, 10 Apr 2013 00:32:31 -0400 From: "Michael R. Hines" MIME-Version: 1.0 References: <20130324155153.GA8597@redhat.com> <515F3160.4020007@linux.vnet.ibm.com> <515F3948.40205@linux.vnet.ibm.com> <515F42EE.8060203@linux.vnet.ibm.com> <20130409190350.GB8212@redhat.com> <5164BFE3.4040204@linux.vnet.ibm.com> <20130410032449.GA12777@redhat.com> In-Reply-To: <20130410032449.GA12777@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv2] rdma: add a new IB_ACCESS_GIFT flag List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Roland Dreier , qemu-devel@nongnu.org, "linux-rdma@vger.kernel.org" , Yishai Hadas , LKML , Hal Rosenstock , Jason Gunthorpe , Sean Hefty , Christoph Lameter On 04/09/2013 11:24 PM, Michael S. Tsirkin wrote: > Which mechanism do you refer to? You patches still seem to pin each > page in guest memory at some point, which will break all COW. In > particular any pagemap tricks to detect duplicates on source that I > suggested won't work. Sorry, I mispoke. I'm reffering to dynamic server page registration. Of course it does not eliminate pinning - but it does mitigate the foot print of the VM as a feature that was requested. I have implemented it and documented it. - Michael >> On 04/09/2013 03:03 PM, Michael S. Tsirkin wrote: >>> presumably is_dup_page reads the page, so should not break COW ... >>> >>> I'm not sure about the cgroups swap limit - you might have >>> too many non COW pages so attempting to fault them all in >>> makes you exceed the limit. You really should look at >>> what is going on in the pagemap, to see if there's >>> measureable gain from the patch. >>> >>> >>> On Fri, Apr 05, 2013 at 05:32:30PM -0400, Michael R. Hines wrote: >>>> Well, I have the "is_dup_page()" commented out.......when RDMA is >>>> activated..... >>>> >>>> Is there something else in QEMU that could be touching the page that >>>> I don't know about? >>>> >>>> - Michael >>>> >>>> >>>> On 04/05/2013 05:03 PM, Roland Dreier wrote: >>>>> On Fri, Apr 5, 2013 at 1:51 PM, Michael R. Hines >>>>> wrote: >>>>>> Sorry, I was wrong. ignore the comments about cgroups. That's still broken. >>>>>> (i.e. trying to register RDMA memory while using a cgroup swap limit cause >>>>>> the process get killed). >>>>>> >>>>>> But the GIFT flag patch works (my understanding is that GIFT flag allows the >>>>>> adapter to transmit stale memory information, it does not have anything to >>>>>> do with cgroups specifically). >>>>> The point of the GIFT patch is to avoid triggering copy-on-write so >>>>> that memory doesn't blow up during migration. If that doesn't work >>>>> then there's no point to the patch. >>>>> >>>>> - R. >>>>>