Re: [Qemu-devel] [PATCH] qcow2: Metadata preallocation

[Kevin Wolf <kwolf@redhat.com>]

Avi Kivity schrieb:
>> Even with improved concurrent cluster allocation, you might profit from
>> metadata preallocation by having less fragmented qcow2 images which
>> avoids splitting up requests. Not sure if this is relevant in practice
>> though.
> 
> What I meant was that I prefer changes that improve performance 
> throughout the lifetime of the image rather than the initial writes, 
> especially as there's a space tradeoff. 

Avoiding fragmentation could improve performance during normal operation
(that is, as long as you don't use snapshots). And I wouldn't worry
about the space tradeoff: Metadata for a 10 GB image is under 2 MB, and
a good part of it would be needed anyway.

But I completely agree that it is not the solution to all of our problems.

Kevin