Re: [Libguestfs] [libnbd] How close are we to declaring a stable API?

On 6/29/19 5:25 AM, Richard W.M. Jones wrote: > As the subject says, how close are we to being able to declare a > stable API for libnbd? > > I believe these are the main topics: > > * Do we need to have an extra thread for writing? I'm unclear about > whether b92392b717 (which allows the state machine to break during > reply processing) means we definitely don't need threads. I imagine > that two threads doing simultaneous send(2) and recv(2) calls could > still improve performance (eg. having two cores copying skbs from > userspace to and from kernel). It's hard to see how simultaneous send() and recv() with nonblocking sockets will do any better across two threads than one. If it was blocking, then it makes total sense, but since we have non-blocking I/O, I'm not seeing that it will make any noticeable difference. That said, I do know that you were experimenting at one point about adding a way to offload writing to a user-controlled thread, and maybe it's still worth playing with that a bit more.