From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:45446) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QosyE-00041O-Sq for qemu-devel@nongnu.org; Thu, 04 Aug 2011 04:08:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QosyB-00021H-C7 for qemu-devel@nongnu.org; Thu, 04 Aug 2011 04:07:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:18072) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QosyB-000217-4z for qemu-devel@nongnu.org; Thu, 04 Aug 2011 04:07:55 -0400 Date: Thu, 4 Aug 2011 09:07:43 +0100 From: "Daniel P. Berrange" Message-ID: <20110804080743.GA14075@redhat.com> References: <4E395D19.4050302@novell.com> <4E3960EF.60603@redhat.com> <4E3A151F.1040205@novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4E3A151F.1040205@novell.com> Subject: Re: [Qemu-devel] [libvirt] speeding up qemu core dumps Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jim Fehlig Cc: LibVir , Eric Blake , qemu-devel@nongnu.org On Wed, Aug 03, 2011 at 09:42:23PM -0600, Jim Fehlig wrote: > Eric Blake wrote: > > On 08/03/2011 08:37 AM, Jim Fehlig wrote: > >> http://lists.nongnu.org/archive/html/qemu-devel/2011-02/msg01156.html > >> > >> I thought there were more discussions on the topic but can only find the > >> above thread ATM. > >> > >> Do folks here have objections to increasing the migration speed prior to > >> core dump? If not, any suggestions for a value? I set the migration > >> speed to 1G in doCoreDump() prior to calling qemuMigrationToFile() with > >> following improvement dumping a 4G guest > > > > Why any limit at all? When dumping to file rather than network, I > > can't think of any justification for a default limit when targetting a > > local drive (a particular installation may have a reasonable limit, > > especially if the file involved happens to use a network - think > > NFS). It seems like it would make sense to override the qemu defaults > > and go with unlimited speed for faster dump and save operations. > > Agreed, 1G was just a test value, but I'm haven't yet figured out how to > define unlimited. From libvirt json monitor connection I tried > migrate_set_speed with INT64_MAX, but that was invalid. Using qemu > monitor directly, I can go as high as INT64_MAX-512 > > (qemu) migrate_set_speed 9223372036854775295B > (qemu) migrate_set_speed 9223372036854775296B > invalid size > > Any hints on proper way to set unlimited migration speed? The code doesn't seem to have a way to set a truely unlimited rate, but even INT64_MAX / 2 would be more than sufficient for us to max out the host OS storage throughput Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|