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 disks for the second time with clean shutdowns that is being investigated. 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 (14): 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: accept io_uring as option 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 qemu-nbd: adds option for aio engines tests/qemu-iotest: enable testing with qemu-io aio options MAINTAINERS | 8 + block.c | 22 ++ block/Makefile.objs | 3 + block/file-posix.c | 99 ++++++-- block/io_uring.c | 439 +++++++++++++++++++++++++++++++++++ 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.c | 11 +- qemu-io.c | 25 +- qemu-nbd.c | 12 +- stubs/Makefile.objs | 1 + stubs/io_uring.c | 32 +++ tests/qemu-iotests/check | 14 +- tests/qemu-iotests/common.rc | 10 + util/async.c | 36 +++ 20 files changed, 746 insertions(+), 51 deletions(-) create mode 100644 block/io_uring.c create mode 100644 stubs/io_uring.c -- 2.21.0