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

[Juan Quintela <quintela@redhat.com>]

Eric Blake <eblake@redhat.com> wrote:
> On 08/13/2012 04:50 AM, Juan Quintela wrote:
>> Hi
>> 
>> This modifies the output of info migrate/qmp_query_migrate to add the
>> stats that I got request for.
>> 
>> - It moves total time to MigrationInfo instead of ram (luiz suggestion)
>
> Now's the time to do this, since the stat is new to 1.2 and we haven't
> yet made a release with it.
>
> Should we also rename 'MigrationInfo' to 'MigrationRamInfo', so that we
> don't make a similar mistake in the future of putting a stat in the
> wrong category?

Luiz?  I dont' care one way or the other O:-)

>> What do I want to know:
>> 
>> - is there any stat that you want?  Once here, adding a new one should
>>   be easy.
>
> 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.

>> 
>> - examples are not done, waiting until people agree with what params
>>   are needed.
>
> Fair enough for RFC purposes.
>
>> 
>> - luiz added in case he has QMP commets.
>> 
>> - erik added for libvirt comments.
>
> Eric, actually.

Sorry :p

Later, Juan.