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

[Florian Heigl <florian.heigl@xxxxxxxxx>]

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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