Re: [RFC PATCH 0/3] qemu: Propagate cluster size to new qcow2 images
On Wed, Aug 26, 2020 at 10:32:04 -0500, Eric Blake wrote:
On 8/26/20 9:56 AM, Peter Krempa wrote:
> Cluster size may have performatnce implications. Propagate the cluster
> size used by the original image to any copy or overlay.
>
> Peter Krempa (3):
> qemu: monitor: Detect image cluster size from
> 'query-named-block-nodes'
> qemu: block: Allow specifying cluster size when using
> 'blockdev-create'
> qemuBlockStorageSourceCreateDetectSize: Propagate cluster size for
> 'qcow2'
It's not as flexible as allowing the user to customize sizes, but it
definitely makes sense and is a sane heuristic, better than adccidentally
creating an overlay with 64k clusters atop a base image with 1M clusters.
Actually, I'll modify the condition in patch 3 to also check that the
configured cluster size in the new image is 0 before applying one from
the template image. That way it will be simpler to wire up configurable
cluster size by just dealing with the XML.
Series:
Reviewed-by: Eric Blake <eblake(a)redhat.com>
Thanks I'll push it soon.