On Mon, Nov 04, 2019 at 11:32:33AM +0100, Stefan Hajnoczi wrote:
> On Fri, Oct 25, 2019 at 06:04:29PM +0200, Stefan Hajnoczi wrote:
> > v11:
> >  * Drop fd registration because it breaks QEMU's file locking and will need to
> >    be resolved in a separate patch series
> >  * Drop line-wrapping changes that accidentally broke several qemu-iotests
> > 
> > v10:
> >  * Dropped kernel submission queue polling, it requires root and has additional
> >    limitations.  It should be benchmarked and considered for inclusion later,
> >    maybe even together with kernel side changes.
> >  * Add io_uring_register_files() return value to trace_luring_fd_register()
> >  * Fix indentation in luring_fd_unregister()
> >  * Set s->fd_reg.fd_array to NULL after g_free() to avoid dangling pointers
> >  * Simplify fd registration code
> >  * Add luring_fd_unregister() and call it from file-posix.c to prevent
> >    fd leaks
> >  * Add trace_luring_fd_unregister() trace event
> >  * Add missing space to qemu-img command-line documentation
> >  * Update MAINTAINERS file [Julia]
> >  * Rename MAX_EVENTS to MAX_ENTRIES [Julia]
> >  * Define ioq_submit() before callers so the prototype isn't necessary [Julia]
> >  * Declare variables at the beginning of the block in luring_init() [Julia]
> > 
> > This patch series is based on Aarushi Mehta's v9 patch series written for
> > Google Summer of Code 2019:
> > 
> >   https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg00179.html
> > 
> > It adds a new AIO engine that uses the new Linux io_uring API.  This is the
> > successor to Linux AIO with a number of improvements:
> > 1. Both O_DIRECT and buffered I/O work
> > 2. fdatasync(2) is supported (no need for a separate thread pool!)
> > 3. True async behavior so the syscall doesn't block (Linux AIO got there to some degree...)
> > 4. Advanced performance optimizations are available (file registration, memory
> >    buffer registration, completion polling, submission polling).
> > 
> > Since Aarushi has been busy, I have taken up this patch series.  Booting a
> > guest works with -drive aio=io_uring and -drive aio=io_uring,cache=none with a
> > raw file on XFS.
> > 
> > I currently recommend using -drive aio=io_uring only with host block devices
> > (like NVMe devices).  As of Linux v5.4-rc1 I still hit kernel bugs when using
> > image files on ext4 or XFS.
> > 
> > Aarushi Mehta (15):
> >   configure: permit use of io_uring
> >   qapi/block-core: add option for io_uring
> >   block/block: add BDRV flag for io_uring
> >   block/io_uring: implements interfaces for io_uring
> >   stubs: add stubs for io_uring interface
> >   util/async: add aio interfaces for io_uring
> >   blockdev: adds bdrv_parse_aio to use io_uring
> >   block/file-posix.c: extend to use io_uring
> >   block: add trace events for io_uring
> >   block/io_uring: adds userspace completion polling
> >   qemu-io: adds option to use aio engine
> >   qemu-img: adds option to use aio engine for benchmarking
> >   qemu-nbd: adds option for aio engines
> >   tests/qemu-iotests: enable testing with aio options
> >   tests/qemu-iotests: use AIOMODE with various tests
> > 
> >  MAINTAINERS                   |   9 +
> >  qapi/block-core.json          |   4 +-
> >  configure                     |  27 +++
> >  block/Makefile.objs           |   3 +
> >  stubs/Makefile.objs           |   1 +
> >  include/block/aio.h           |  16 +-
> >  include/block/block.h         |   2 +
> >  include/block/raw-aio.h       |  12 +
> >  block.c                       |  22 ++
> >  block/file-posix.c            |  99 ++++++--
> >  block/io_uring.c              | 433 ++++++++++++++++++++++++++++++++++
> >  blockdev.c                    |  12 +-
> >  qemu-img.c                    |  11 +-
> >  qemu-io.c                     |  25 +-
> >  qemu-nbd.c                    |  12 +-
> >  stubs/io_uring.c              |  32 +++
> >  util/async.c                  |  36 +++
> >  block/trace-events            |  12 +
> >  qemu-img-cmds.hx              |   4 +-
> >  qemu-img.texi                 |   5 +-
> >  qemu-nbd.texi                 |   4 +-
> >  tests/qemu-iotests/028        |   2 +-
> >  tests/qemu-iotests/058        |   2 +-
> >  tests/qemu-iotests/089        |   4 +-
> >  tests/qemu-iotests/091        |   4 +-
> >  tests/qemu-iotests/109        |   2 +-
> >  tests/qemu-iotests/147        |   5 +-
> >  tests/qemu-iotests/181        |   8 +-
> >  tests/qemu-iotests/183        |   4 +-
> >  tests/qemu-iotests/185        |  10 +-
> >  tests/qemu-iotests/200        |   2 +-
> >  tests/qemu-iotests/201        |   8 +-
> >  tests/qemu-iotests/check      |  15 +-
> >  tests/qemu-iotests/common.rc  |  14 ++
> >  tests/qemu-iotests/iotests.py |  12 +-
> >  35 files changed, 797 insertions(+), 76 deletions(-)
> >  create mode 100644 block/io_uring.c
> >  create mode 100644 stubs/io_uring.c
> 
> Fixed up commit description as requested by Markus.
> 
> Thanks, applied to my block-next tree for QEMU 4.3:
> https://github.com/stefanha/qemu/commits/block-next

Kevin and Max have raised some issues that I will address before this
gets merged into qemu.git/master.

Stefan