Re: [Qemu-devel] CoW image commit+shrink(= make_empty) support

[Paolo Bonzini]

Il 08/06/2012 19:57, Kevin Wolf ha scritto:
>> > 
>> > I agree, doing it like mirroring for new writes on the top layer makes
>> > sense, as long as you are willing to violate the (optional) speed
>> > parameter.  I wouldn't think violating the speed parameter in that case
>> > would be an issue, as long as it is a documented affect of performing a
>> > live commit on the active (top) layer.
> The question is what the speed parameter really means for a live commit
> block job (or for an active mirror). I think it would make sense to
> limit only the speed of I/O that doesn't come from the guest but is from
> the background copying.

Not necessarily, you can throttle the copying speed.  If the I/O from
the guest has bursts, you will pick up the work later when the rate
calms down.

Paolo