diff --git a/block/file-posix.c b/block/file-posix.c index 7a289a9481..c2c94fca66 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -2066,7 +2066,8 @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset, } else if (s->use_linux_aio) { LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs)); assert(qiov->size == bytes); - return laio_co_submit(bs, aio, s->fd, offset, qiov, type); + return laio_co_submit(bs, aio, s->fd, offset, qiov, type, + s->aio_max_batch); #endif } diff --git a/block/linux-aio.c b/block/linux-aio.c index 0dab507b71..88b44fee72 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -334,6 +334,23 @@ static void ioq_submit(LinuxAioState *s) } } +static uint64_t laio_max_batch(LinuxAioState *s, uint64_t dev_max_batch) +{ + uint64_t max_batch = s->aio_context->aio_max_batch ?: DEFAULT_MAX_BATCH; + + /* + * AIO context can be shared between multiple block devices, so + * `dev_max_batch` allows reducing the batch size for latency-sensitive + * devices. + */ + max_batch = MIN_NON_ZERO(dev_max_batch, max_batch); + + /* limit the batch with the number of available events */ + max_batch = MIN_NON_ZERO(MAX_EVENTS - s->io_q.in_flight, max_batch); + + return max_batch; +} + void laio_io_plug(BlockDriverState *bs, LinuxAioState *s) { s->io_q.plugged++; @@ -349,15 +366,11 @@ void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s) } static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, - int type) + int type, uint64_t dev_max_batch) { LinuxAioState *s = laiocb->ctx; struct iocb *iocbs = &laiocb->iocb; QEMUIOVector *qiov = laiocb->qiov; - int64_t max_batch = s->aio_context->aio_max_batch ?: DEFAULT_MAX_BATCH; - - /* limit the batch with the number of available events */ - max_batch = MIN_NON_ZERO(MAX_EVENTS - s->io_q.in_flight, max_batch); switch (type) { case QEMU_AIO_WRITE: @@ -378,7 +391,7 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, s->io_q.in_queue++; if (!s->io_q.blocked && (!s->io_q.plugged || - s->io_q.in_queue >= max_batch)) { + s->io_q.in_queue >= laio_max_batch(s, dev_max_batch))) { ioq_submit(s); } @@ -386,7 +399,8 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, } int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd, - uint64_t offset, QEMUIOVector *qiov, int type) + uint64_t offset, QEMUIOVector *qiov, int type, + uint64_t dev_max_batch) { int ret; struct qemu_laiocb laiocb = { @@ -398,7 +412,7 @@ int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd, .qiov = qiov, }; - ret = laio_do_submit(fd, &laiocb, offset, type); + ret = laio_do_submit(fd, &laiocb, offset, type, dev_max_batch); if (ret < 0) { return ret; } diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h index 251b10d273..ebd042fa27 100644 --- a/include/block/raw-aio.h +++ b/include/block/raw-aio.h @@ -51,7 +51,8 @@ typedef struct LinuxAioState LinuxAioState; LinuxAioState *laio_init(Error **errp); void laio_cleanup(LinuxAioState *s); int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd, - uint64_t offset, QEMUIOVector *qiov, int type); + uint64_t offset, QEMUIOVector *qiov, int type, + uint64_t dev_max_batch); void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context); void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context); void laio_io_plug(BlockDriverState *bs, LinuxAioState *s);