On 10/27/21 14:21, Richard W.M. Jones wrote: > NOTE: This is not complete, I'm just posting it for early review. In > particular I need to test and benchmark this a lot more to make sure > it really is a performance improvement. > > At the moment nbdkit-vddk-plugin suffers because it works > synchronously. We found in testing that copying multiple VMs in > parallel is much faster than copying a single VM, the obvious reason > being that each single nbdkit spends a lot of time waiting on round > trips to the VMware server. > > Since VDDK 6.0 (but only implemented in VDDK 6.7+) the library has > offered a form of asynchronous read and write operation. We can use > that to implement the parallel thread model, hopefully allowing > multiple outstanding read/write commands to overlap in flight. > > One thing of note is that multi-conn is probably not possible without > a lot more work. The reason is that VDDK locks the backing disk when > you open a handle, so multiple connections (ie. handles) cannot be > opened. I am also not clear if VDDK/VMware offers the correct data > integrity guarantees to allow us to implement multi-conn, and since > the whole lot of closed source there's no easy way to find out. > > Rich. > >
For the first four patches: Acked-by: Laszlo Ersek <[email protected]> Will need a bit more time for the last one. Thanks Laszlo _______________________________________________ Libguestfs mailing list [email protected] https://listman.redhat.com/mailman/listinfo/libguestfs
