[Libguestfs] [libnbd] GSoC21: IO_uring optimization questions

[Richard W.M. Jones]

On Wed, Mar 31, 2021 at 05:55:34PM +0100, Stefan Hajnoczi wrote:
> On Tue, Mar 30, 2021 at 06:05:57PM +0100, Richard W.M. Jones wrote:
> > [Adding Stefan: Have we retro-fitted io_uring into any other libraries?]
> 
> Not that I'm aware of. You could check Fedora or another Linux distro's
> packages to find what depends on liburing and then investigate those
> packages.

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