Re: [Qemu-devel] [PATCH 9/9] block-migration: add named dirty bitmaps migration

[Paolo Bonzini]

On 11/12/2014 15:17, Vladimir Sementsov-Ogievskiy wrote:
> Just migrate parts of dirty bitmaps, corresponding to the block being
> migrated. Also, skip block migration if it is disabled (blk parameter
> of migrate command is false).
> 
> Skipping shared sectors: bitmaps are migrated independently of this,
> just send blk without block data.

I think dirty bitmaps should be migrated separately from the block
migration.  It makes a lot of sense to migrate them even if you are not
using block migration.

Compared to new flags, the availability of migration capabilities can be
queried via query-migrate-capabilities before actually invoking the
migration.  So they are preferred, and you should add a migration
capability instead of a new argument.

The bitmaps are transmitted many times in their entirety, but only the
last copy actually means something.  The others are lost.  This means
you should use the non-live interface (register_savevm).  This will
simplify the code a lot.

Paolo