[Adding Stefan: Have we retro-fitted io_uring into any other libraries?] Welcome Abhay, On Tue, Mar 30, 2021 at 09:33:17PM +0530, Abhay Raj Singh wrote: This would be nice and self-contained. Does "socket wrapper" mean adding another struct socket_ops defined in lib/internal.h and implemented so far in lib/socket.c (for plain sockets) and lib/crypto.c (for TLS sockets)? As an aside, libnbd only makes socket calls in a few places: $ git grep -- '->recv' generator/states-reply.c: r = h->sock->ops->recv (h, h->sock, h->rbuf, h->rlen); generator/states-reply.c: /* sock->ops->recv called set_error already. */ generator/states.c: r = h->sock->ops->recv (h, h->sock, rbuf, rlen); generator/states.c: /* sock->ops->recv called set_error already. */ $ git grep -- '->send' generator/states.c: r = h->sock->ops->send (h, h->sock, h->wbuf, h->wlen, h->wflags); generator/states.c: /* sock->ops->send called set_error already. */ (Also you'll want to look for '->pending', '->get_fd', '->shut_writes', '->close'). If there's a new API then that's going to require every existing user to opt in, which isn't nice for those users. They would need to choose io_uring (and risk not working on many platforms) or try to support both APIs. So the bar to doing this way must be very high - only if it's not possible any other way. You could also test against qemu-nbd, although it is also not using io_uring AFAIK. Also you could test against a simple hand-written NBD server implemented using io_uring. Or maybe there will be enough of a performance difference against unmodified nbdkit. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org

On Wed, Mar 31, 2021 at 05:55:34PM +0100, Stefan Hajnoczi wrote: Yes that's a good point - it's likely they would depend on liburing. A few queries like: # dnf repoquery --whatrequires 'liburing' --qf '%{SOURCERPM}' # dnf repoquery --whatrequires 'liburing.so.1()(64bit)' --qf '%{SOURCERPM}' shows only: folly-2021.03.15.00-1.fc33.src.rpm mpd-0.22.6-1.fc33.src.rpm qemu-5.1.0-9.fc33.src.rpm samba-4.13.5-0.fc33.src.rpm - "folly" is "An open-source C++ library developed and used at Facebook" (https://github.com/facebook/folly). Usage seems to be confined to a couple of experimental backends. - "mpd" "Music Player Daemon (MPD)" (https://www.musicpd.org). Fairly extensive use of io_uring for as an optional event backend. However it's a server so not directly relevant to us. qemu & samba we know about. Abhay: It might be worth looking at qemu's use of io_uring in block/file-posix.c Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html

Hello again! Sorry for the late update I have family functions so had to travel. I have prepared a draft proposal which you can visit here: https://docs.google.com/document/d/14gEFCA9vc59fqnZB_TxZ2ILcjk90o8_z0fEKt... I have also submitted the draft on the GSoC site. Please suggest if I should add something more or present it differently. Humble Regards, -- Abhay (rathod-sahaab)

Thanks, I have applied all the changes I will be thanksful if you can take a look https://docs.google.com/document/d/14gEFCA9vc59fqnZB_TxZ2ILcjk90o8_z0fEKt... Thanks! Sincerely, -- Abhay (rathod-sahaab)