Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937039Ab3DJQKb (ORCPT ); Wed, 10 Apr 2013 12:10:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60179 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932091Ab3DJQK3 (ORCPT ); Wed, 10 Apr 2013 12:10:29 -0400 Date: Wed, 10 Apr 2013 18:05:39 +0300 From: "Michael S. Tsirkin" To: "Michael R. Hines" Cc: Roland Dreier , Jason Gunthorpe , Sean Hefty , Hal Rosenstock , Yishai Hadas , Christoph Lameter , "linux-rdma@vger.kernel.org" , LKML , qemu-devel@nongnu.org Subject: Re: [PATCHv2] rdma: add a new IB_ACCESS_GIFT flag Message-ID: <20130410150539.GA24381@redhat.com> References: <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> <5164EB5F.80403@linux.vnet.ibm.com> <20130410053255.GC12777@redhat.com> <516589C8.1040606@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <516589C8.1040606@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1944 Lines: 54 On Wed, Apr 10, 2013 at 11:48:24AM -0400, Michael R. Hines wrote: > > There's a very nice, simple client/server RDMA application on the > internet you can use to test your patch. > > http://thegeekinthecorner.wordpress.com/2010/09/28/ > rdma-read-and-write-with-ib-verbs/ > > This guy provides the source code which dumps several gigabytes over RDMA > to the other side. > > There's no need to run QEMU to test your patch, > assuming you have access to infiniband hardware. > > - Michael Does this app have any COW pages? > On 04/10/2013 01:32 AM, Michael S. Tsirkin wrote: > > On Wed, Apr 10, 2013 at 12:32:31AM -0400, Michael R. Hines wrote: > > 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 > > Okay, but GIFT is supposed to be used on send side: it's only allowed > with local/remote read access, and serves to reduce memory usage > on send side. > For example, disable zero page detection and look at memory usage > on send side before and after migration. > Dynamic registration on the receive side is nice but seems > completely unrelated ... > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/