qcow2: Discard VM state in active L1 after creating snapshot
During savevm, the VM state is written to the active L1 of the image and then a snapshot is taken. After that, the VM state isn't needed any more in the active L1 and should be discarded. This is implemented by this patch. The impact of not discarding the VM state is that a snapshot can never become smaller than any previous snapshot (because it would be padded with old VM state), and more importantly that future savevm operations cause unnecessary COWs (with associated flushes), which makes subsequent snapshots much slower. Signed-off-by: NKevin Wolf <kwolf@redhat.com> Reviewed-by: NMax Reitz <mreitz@redhat.com>
Showing
想要评论请 注册 或 登录