On 04/02/2015 15:34, Daniel P. Berrange wrote: > > GIO doesn't provide writev either, so it's not a good match for > > non-encrypted migration, which really tries hard to do no copies in > > userspace. > > Ok, maybe RDMA will still need QEMUFile, but for non-encrypted TCP > I'd hope to be able to achieve zero-copy with the new API too - it > would certainly be my intention/goal.
For GIO/GIOChannel, you'd have to choose between zerocopy and many syscalls, or one copy and few syscalls. Since every page has two iov entries, one of which is just 8 bytes, one copy and few syscalls is probably faster---but still only half the speed of writev. Paolo
