Re: [Qemu-devel] [RFC 0/7] Migration stats

[Eric Blake <eblake@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1131 bytes --]

On 08/13/2012 09:08 AM, Juan Quintela wrote:
>>
>> Should we have some sort of stat for the number of pages that are sent
>> more than once, and/or for the maximum count of times that a given page
>> was sent?  Having hot/cold page analysis might make it easier to decide
>> in the future which pages to avoid sending until the very end, and
>> knowing how many pages are sent multiple times as well as the maximum
>> times any one page is sent might help.
> 
> That is not trivial to do without "duplicating" the bitmap. Bitmap is
> already quite big on machines with huge memory.  Adding a field to show
> how many times a page have been sent sounds too much.  Furthermore, how
> could this information could be used externally.

No big loss, then.  I was just wondering out loud, and don't really have
a particular need for this information.

I guess with XBZRLE, you _do_ have a count of how many cache hits you
had, which is somewhat related (a cache hit implies sending a page more
than once).

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


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 620 bytes --]