mirror of
https://github.com/qemu/qemu.git
synced 2026-02-04 05:35:39 +00:00
047dabef97
AioContext has its own io_uring instance for file descriptor monitoring. The disk I/O io_uring code was developed separately. Originally I thought the characteristics of file descriptor monitoring and disk I/O were too different, requiring separate io_uring instances. Now it has become clear to me that it's feasible to share a single io_uring instance for file descriptor monitoring and disk I/O. We're not using io_uring's IOPOLL feature or anything else that would require a separate instance. Unify block/io_uring.c and util/fdmon-io_uring.c using the new aio_add_sqe() API that allows user-defined io_uring sqe submission. Now block/io_uring.c just needs to submit readv/writev/fsync and most of the io_uring-specific logic is handled by fdmon-io_uring.c. There are two immediate advantages: 1. Fewer system calls. There is no need to monitor the disk I/O io_uring ring fd from the file descriptor monitoring io_uring instance. Disk I/O completions are now picked up directly. Also, sqes are accumulated in the sq ring until the end of the event loop iteration and there are fewer io_uring_enter(2) syscalls. 2. Less code duplication. Note that error_setg() messages are not supposed to end with punctuation, so I removed a '.' for the non-io_uring build error message. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-ID: <20251104022933.618123-15-stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>