v5: * Add back BDRV_O_IO_URING check that was dropped accidentally in v3 [Kevin]
v4: * Drop unnecessary changes in Patch 8 [Stefano] v3: * Reword BlockdevAioOptions QAPI schema commit description [Markus] * Increase QAPI "Since: 4.2" to "Since: 5.0" * Explain rationale for io_uring stubs in commit description [Kevin] * Tried to use file.aio=io_uring instead of BDRV_O_IO_URING but it's really hard to make qemu-iotests work. Tests build blkdebug: and other graphs so the syntax for io_uring is dependent on the test case. I scrapped this approach and went back to a global flag. v2: * 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 This patch series is based on Aarushi Mehta's v9 patch series written for Outreachy 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 + block.c | 22 ++ block/Makefile.objs | 3 + block/file-posix.c | 98 ++++++-- block/io_uring.c | 433 ++++++++++++++++++++++++++++++++++ block/trace-events | 12 + 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 | 4 +- 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 | 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 +- util/async.c | 36 +++ 35 files changed, 797 insertions(+), 75 deletions(-) create mode 100644 block/io_uring.c create mode 100644 stubs/io_uring.c -- 2.24.1
