Re: [Libguestfs] nbd_aio_p{read,write} responsibilities

Another way to proceed here could be to write a from-scratch version of nbdcopy using io_uring, to get a feel for the "shape" of what that would look like. Then translate back from that into an NBD API proposal. For simplicity in implementation: - Only implement NBD oldstyle protocol, which is very simple. You can find it documented here: https://gitlab.com/nbdkit/nbdkit/-/blob/dd894ae009c16810605252ee6996d329c... nbdkit supports oldstyle if you add the -o option. - Only do NBD server -> NBD server copies, forget about local files, pipes, etc. - Don't implement any of the options, synchronous mode, etc. Just hard-code all the settings. I'm interested in seeing what this would look like. Also it might answer a few questions I have: - Do we need to use threads in nbdcopy if we have io_uring? - How many io_urings should we use? - Can we avoid kernel-userspace copies? Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/