[Qemu-devel] [PATCH 0/4] qcow2: Improve cluster refcount update

[Laurent Vivier]

This series of patches improves qcow2 performance with O_DIRECT
when the qcow2 file is empty and we begin to fill it.

For instance, an OS install took 12 min 56 sec without these patches,
and 8 min 37 sec with it (this has been measured with KVM).

To do that, they improve the updating of the clusters refcounts.

[PATCH 1/4] qcow2: Clean-up update_cluster_refcount().
[PATCH 2/4] qcow2: Allow update_cluster_refcount() to update several
                   clusters refcount.
[PATCH 3/4] qcow2: Align I/O access to l2 table and refcount block.
[PATCH 4/4] qcow2: detect if no disk cache

Laurent
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