From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48052) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZJd4O-0006Ei-5X for qemu-devel@nongnu.org; Mon, 27 Jul 2015 03:43:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZJd4L-0006UT-DE for qemu-devel@nongnu.org; Mon, 27 Jul 2015 03:43:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41694) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZJd4L-0006U3-8A for qemu-devel@nongnu.org; Mon, 27 Jul 2015 03:43:29 -0400 Date: Mon, 27 Jul 2015 13:13:18 +0530 From: Amit Shah Message-ID: <20150727074318.GF12267@grmbl.mre> References: <1434450415-11339-1-git-send-email-dgilbert@redhat.com> <1434450415-11339-36-git-send-email-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434450415-11339-36-git-send-email-dgilbert@redhat.com> Subject: Re: [Qemu-devel] [PATCH v7 35/42] Don't sync dirty bitmaps in postcopy List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, liang.z.li@intel.com, qemu-devel@nongnu.org, luis@cs.umu.se, pbonzini@redhat.com, david@gibson.dropbear.id.au On (Tue) 16 Jun 2015 [11:26:48], Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > Once we're in postcopy the source processors are stopped and memory > shouldn't change any more, so there's no need to look at the dirty > map. > > There are two notes to this: > 1) If we do resync and a page had changed then the page would get > sent again, which the destination wouldn't allow (since it might > have also modified the page) > 2) Before disabling this I'd seen very rare cases where a page had been > marked dirtied although the memory contents are apparently identical I suppose we don't know why. Any way to send a message to the dest with this info, so the dest can print out something? That'll help in debugging. (I'm suggesting sending a message to the dest, because after a migration, we don't ever think of looking at messages on the src. And chances are the dest could blow up after a migration is successful because of such "corruption".) > Signed-off-by: Dr. David Alan Gilbert > Reviewed-by: David Gibson Reviewed-by: Amit Shah Amit