Re: [Qemu-devel] [PATCH 00/18] Migration thread lite (20121029)

[Juan Quintela]

Chegu Vinod <address@hidden> wrote:
> On 10/29/2012 9:21 AM, Vinod, Chegu wrote:
>> Date: Mon, 29 Oct 2012 15:11:25 +0100
>> From: Juan Quintela <address@hidden>
>> To: address@hidden
>> Cc: address@hidden, address@hidden, address@hidden,
>>      address@hidden
>> Subject: [Qemu-devel] [PATCH 00/18] Migration thread lite (20121029)
>>
>> Hi
>>
>> After discussing with Anthony and Paolo, this is the minimal migration 
>> thread support that we can do for 1.3.
>>
>> - fixed all the comments (thanks eric, paolo and orit).
>> - buffered_file.c remains until 1.4.
>> - testing for vinod showed very nice results, that is why the bitmap
>>    handling optimizations remain.
>
> Hi Juan,
>
> Is there any value in calling the migration_bitmap_synch() routine in
> the ram_save_setup() . All the
> pages were marked as dirty to begin with...so can't we just assume
> that all pages need to be sent
> and proceed ?

I haven't investigated it fully, but if we don't do it, we end sending
each page twice.  As said that needs more investigation.

>
> migration_bitmap_synch () - still remains an expensive call. and the
> very first call to seems to be ~3x times
>  more expensive than the subsequent calls. For large guests (>128G
> guests) this is multiple seconds...and
> it freezes the OS instance.

Will try to implement the other optimizaton, but that is 1.4 material
:-(

Later, Juan.)