From: Prasad Pandit <p...@fedoraproject.org> Libaio defines IO_CMD_FDSYNC command to sync all outstanding asynchronous I/O operations, by flushing out file data to the disk storage.
Enable linux-aio to submit such aio request. This helps to reduce latency induced via pthread_create calls by thread-pool (aio=threads). Signed-off-by: Prasad Pandit <p...@fedoraproject.org> --- block/file-posix.c | 12 ++++++++++++ block/linux-aio.c | 5 ++++- 2 files changed, 16 insertions(+), 1 deletion(-) v2: if IO_CMD_FDSYNC is not supported by the kernel, fallback on thread-pool flush. -> https://lists.nongnu.org/archive/html/qemu-devel/2024-03/msg01986.html diff --git a/block/file-posix.c b/block/file-posix.c index 35684f7e21..4f2195d01d 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -2599,6 +2599,18 @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs) if (raw_check_linux_io_uring(s)) { return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH); } +#endif +#ifdef CONFIG_LINUX_AIO + if (raw_check_linux_aio(s)) { + ret = laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0); + if (ret >= 0) { + /* + * if AIO_FLUSH is supported return + * else fallback on thread-pool flush. + */ + return ret; + } + } #endif return raw_thread_pool_submit(handle_aiocb_flush, &acb); } diff --git a/block/linux-aio.c b/block/linux-aio.c index ec05d946f3..d940d029e3 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -384,6 +384,9 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, case QEMU_AIO_READ: io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset); break; + case QEMU_AIO_FLUSH: + io_prep_fdsync(iocbs, fd); + break; /* Currently Linux kernel does not support other operations */ default: fprintf(stderr, "%s: invalid AIO request type 0x%x.\n", @@ -412,7 +415,7 @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov, AioContext *ctx = qemu_get_current_aio_context(); struct qemu_laiocb laiocb = { .co = qemu_coroutine_self(), - .nbytes = qiov->size, + .nbytes = qiov ? qiov->size : 0, .ctx = aio_get_linux_aio(ctx), .ret = -EINPROGRESS, .is_read = (type == QEMU_AIO_READ), -- 2.44.0