[Qemu-devel] [PATCH v8 00/16] Add support for io_uring

[Aarushi Mehta]

This patch series adds support for the newly developed io_uring Linux AIO
interface. Linux io_uring is faster than Linux's AIO asynchronous I/O code,
offers efficient buffered asynchronous I/O support, the ability to do I/O
without performing a system call via polled I/O, and other efficiency 
enhancements.

Testing it requires a host kernel (5.1+) and the liburing library.
Use the option -drive aio=io_uring to enable it.

Benchmarks for the system at https://github.com/rooshm/benchmarks
io_uring has similar performance as libaio but supports cache=writeback.
Further performance enhancement will be implemented

There is currently an -EIO output when guests are booted from io_uring on ext4,
the error is reported upstream.
https://lore.kernel.org/linux-block/20190723080701.GA3198@stefanha-x1.localdomain/

v8:
- adds fd_registration

v7:
- completes io-tests options
- misc fixes

v6:
- add slow path for short-read
- hooks up fsync
- enables qemu-iotests with aio options
- adds bdrv_parse_aio

v5:
- Adds completion polling
- Extends qemu-io
- Adds qemu-iotest

v4:
- Add error handling
- Add trace events
- Remove aio submission based code

Aarushi Mehta (16):
  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
  block/io_uring: adds fd registration

 MAINTAINERS                   |   8 +
 block.c                       |  22 ++
 block/Makefile.objs           |   3 +
 block/file-posix.c            |  99 +++++--
 block/io_uring.c              | 522 ++++++++++++++++++++++++++++++++++
 block/trace-events            |  13 +
 blockdev.c                    |  12 +-
 configure                     |  27 ++
 include/block/aio.h           |  16 +-
 include/block/block.h         |   2 +
 include/block/raw-aio.h       |  12 +
 qapi/block-core.json          |   4 +-
 qemu-img-cmds.hx              |   2 +-
 qemu-img.c                    |  11 +-
 qemu-img.texi                 |   5 +-
 qemu-io.c                     |  25 +-
 qemu-nbd.c                    |  12 +-
 qemu-nbd.texi                 |   4 +-
 stubs/Makefile.objs           |   1 +
 stubs/io_uring.c              |  32 +++
 tests/qemu-iotests/028        |   3 +-
 tests/qemu-iotests/058        |   2 +-
 tests/qemu-iotests/089        |   4 +-
 tests/qemu-iotests/091        |   7 +-
 tests/qemu-iotests/109        |   3 +-
 tests/qemu-iotests/147        |   5 +-
 tests/qemu-iotests/181        |  10 +-
 tests/qemu-iotests/183        |   7 +-
 tests/qemu-iotests/185        |  17 +-
 tests/qemu-iotests/200        |   3 +-
 tests/qemu-iotests/201        |  10 +-
 tests/qemu-iotests/check      |  15 +-
 tests/qemu-iotests/common.rc  |  14 +
 tests/qemu-iotests/iotests.py |   9 +-
 util/async.c                  |  36 +++
 35 files changed, 899 insertions(+), 78 deletions(-)
 create mode 100644 block/io_uring.c
 create mode 100644 stubs/io_uring.c

-- 
2.21.0