[Xen-devel] Re: [Xen-users] old issue after 1024 live migrations seems to still exist.

[Pasi Kärkkäinen <pasik@xxxxxx>]

Adding xen-devel to the CC list..

On Wed, Jul 21, 2010 at 04:38:28PM +0200, Florian Heigl wrote:
> Hi,
> 
> last month I did some checkig of old Xen issues that I remember and
> found this one to still exist - if you do a high amount of live
> migrations at some point the xen daemon chokes and dies.
> The issue was reported by someone on the list like 4-5 years ago, but
> it seems it hasn't been fixed (not sure if anyone even replied back
> then)
> The Xen version I used to test as 3.4.0 from Oracle VM 2.2
> 
> Basically You just ping-pong one domU and somewhere after 900
> migrations you first see it drop the ball a few times (vm needs to be
> restarted) and then about 100 times later one one of the hosts the xen
> daemon will crash, restart and not be able to boot vm's any more.
> 
> (I waited a while to post this, but about time now I get it done)
> I'm building some power management magic witrh loadbalancing so that
> idle servers can automatically shutdown and startup, and cpu intensive
> vm's can be distributed evenly.That this bug still exists is a
> nightmare: 1024 migrations sounds a lot, but with 128 VMs on a host it
> just equals just 4 migrations per VM, right? Without the loadbalancing
> bit this wouldn't have to happen very often, but I think it's a key
> feature.
> If the RDMA live migration ever comes around, there'd be nothing against it...
> 
> I've also prepared a clumsy script for the test, which can be found here:
> 
> http://wartungsfenster.pastebin.org/410803
> 
> I can open a bug report but i think it'd be best if someone re-test on
> Xen4 first.
> 
> Regards,
> Florian
> 
> p.s.:
> why is live migration so slow (2-3 seconds)  - without sdp i had 2-3
> gbit of bandwidth, the vm was 64MB size  (that means 1/6 second of
> transfer for the main bulk) and idle without networking!
> is it just the gratious arp?
> 
> -- 
> 'Sie brauchen sich um Ihre Zukunft keine Gedanken zu machen'
> 
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