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Re: [Xen-users] Live migration downtime longer when mem < maxmem


  • To: "Marconi Rivello" <marconirivello@xxxxxxxxx>
  • From: "Tim Wood" <twwood@xxxxxxxxx>
  • Date: Fri, 17 Aug 2007 15:41:58 -0700
  • Cc: xen-users@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Fri, 17 Aug 2007 15:42:24 -0700
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  • List-id: Xen user discussion <xen-users.lists.xensource.com>

It may or may not have ever been resolved, but there were some
messages about this a while back... you may have some luck searching
the archives to see if tehre was a conclusive fix:

http://lists.xensource.com/archives/html/xen-devel/2006-12/msg00903.html
http://lists.xensource.com/archives/html/xen-users/2006-09/msg00131.html

-Tim

On 8/8/07, Marconi Rivello <marconirivello@xxxxxxxxx> wrote:
> Hi there,
>
> I am experiencing a weird (at least to me) behavior in live migration.
>
> I have 2 VMs, one with 1024M maxmem and another with 512M maxmem. When i set
> the VM mem to max-mem, I get around 3s of downtime. When I reduce the mem to
> half the max-mem, I get around 20s downtime! I tested with both VMs.
>
> Just a note: both VMs and phys. machines are idle, the network isn't
> dedicated, but the tests were run consecutively and repeated times. I'm also
> working on figuring out why the downtime is longer than a few ms, as
> described in Xen papers. I think it has to do with the switch...
>
> But in the meantime, why on earth should a VM's migration take longer when I
> reduce it's mem?
>
> I appreciate any ideas, theories, or even a trivial explanation that would
> make me look silly :)
>
>  Thanks.
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>

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