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 a rebased and cleaned up version of 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 resolved code review comments from v9.
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 (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 | 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 | 13 +
block.c | 22 ++
block/file-posix.c | 117 +++++--
block/io_uring.c | 581 ++++++++++++++++++++++++++++++++++
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 | 14 +
qemu-img-cmds.hx | 4 +-
qemu-img.texi | 5 +-
qemu-nbd.texi | 4 +-
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 | 12 +-
35 files changed, 982 insertions(+), 80 deletions(-)
create mode 100644 block/io_uring.c
create mode 100644 stubs/io_uring.c
--
2.21.0