From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: request of blkfront may disorder after migration without waiting in suspend phase of migration Date: Tue, 12 Jul 2011 14:23:35 -0400 Message-ID: <20110712182335.GA24828@dumpdata.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: alice wan Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Sun, Jul 10, 2011 at 12:36:06PM +0800, alice wan wrote: > Hi konrad, > > I found the mainline linux 3.0-rc6 xen-blkfront driver doesn't implement > suspend func. In my opinion, the blkfront should wait till responses of all > the pending requests come back, then domu can be suspended, I think you mean blkback. It should be the job of blkback to account for all I/Os and make sure they have completed before migrating? I did have a patch for the 2.6.32 to deal with this but I never was able to reproduce this. Are you able to reproduce this? Can you give me step by step instructions on how to do it? > otherwise, after the migration, vm of target host will request from target > host, meanwhile, the blkback of source host maybe do the pending requests > until they's done. > > if migrate the vm with high io pressure, the requests of this vm may > disorder. > > And i saw the gpl windows pv driver, blkfront will change its state and wait > for blkback closing, after blkback closing, the pending requests definitely > are done. > > More, i did some test with migration, while vm was running dd task, xm > migrate -l . before it suspend, gdb tapdisk2. after migration, new vm > started. then quit gdb, the pending request were written back to disk after > new requests. > > above mentioned is just my opinion, i need your advice and confirmation or > deny > > any help is appreciated. > > > Regards > > wanjia > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel