Re: [Qemu-block] [PATCH v2 08/13] block: Support meta dirty bitmap

[Vladimir Sementsov-Ogievskiy]

On 26.01.2016 09:25, Fam Zheng wrote:
> On Fri, 01/22 15:05, Vladimir Sementsov-Ogievskiy wrote:
> > > In my migration series I need iterators, get granularity, and
> > > something like hbitmap_count  for meta bitmaps. You can add them
> > > here if you want, or I can add them in my series.
> Okay, I can add that.
>
> I have one more question on the interface: what dirty bitmaps are going to be
> migrated? At this moment there are dirty bitmaps created by block jobs
> (drive-mirror), and in-memory dirty bitmaps created for incremental backup;
> later there will be persistent dirty bitmaps owned by block drivers (extended
> version of qcow2, and in QBM driver I'm working on). Which of them are subject
> of migration in your series?
>
> I'm asking because I want to know whether we need to implement multiple meta
> bitmaps on one block dirty bitmap.
>
> Fam
Only named bitmaps are migrated. For now, only qmp-created bitmaps are 
named. So, it can be in-memory dirty bitmaps or, in future, persistent 
dirty bitmaps.

Why multiple meta bitmaps? What is your plan about meta, should it be 
used for something other than migration? There was ideas about async 
loading persistent metabitmaps - maybe here? We can disallow processes 
using meta bitmaps to be simultaneous.

--
Best regards,
Vladimir
* now, @virtuozzo.com instead of @parallels.com. Sorry for this inconvenience.