Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage

[Eric Blake <eblake@redhat.com>]

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On 03/01/2013 07:13 AM, Peter Lieven wrote:
> On 01.03.2013 15:08, Eric Blake wrote:
>> On 03/01/2013 07:06 AM, Peter Lieven wrote:
>>>> Do you have any benchmark numbers?  At any rate, the explanation seems
>>>> sound, so a benchmark should show this.
>>>
>>> Do you have a particular test pattern in mind? If there is nothing
>>> going on
>>> in the VM XBZRLE will not be better than normal copy at all.
>>>
>>> Otherwise you will have N xbzrle misses and 0 xbzrle pages without the
>>> patch
>>> and 0 xbzrle misses and 0 xbzrle pages with the patch.
>>
>> How about a migration of a guest running the synthetic r/w load
>> generator in docs/xbzrle.txt?
>>
> Good idea. I will leave max downtime and bandwidth at default values.
> 
> Would you be happy with 1GB vRAM and 256MB page cache?

Sure - just any run that you can do that shows before and after numbers,
and that is described well enough to be a reproducible test.  Final
statistics on the migration (pages transferred, cache hits and misses,
etc) and time spent on the migration will hopefully show an improvement,
but most important is that they do not show a regression.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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