On Wed, Mar 13, 2024 at 02:19:35PM +0530, Prasad Pandit wrote: > 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 | 7 +++++++ > block/linux-aio.c | 22 +++++++++++++++++++++- > 2 files changed, 28 insertions(+), 1 deletion(-) > > v3: check if host kernel supports aio_fsync call > -> https://lists.nongnu.org/archive/html/qemu-devel/2024-03/msg03210.html > > diff --git a/block/file-posix.c b/block/file-posix.c > index 35684f7e21..a30494d1a8 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -2453,6 +2453,8 @@ static inline bool > raw_check_linux_io_uring(BDRVRawState *s) > #endif > > #ifdef CONFIG_LINUX_AIO > +extern bool laio_has_fdsync(int);
Please declare this in include/block/raw-aio.h alongside the other laio APIs. > + > static inline bool raw_check_linux_aio(BDRVRawState *s) > { > Error *local_err = NULL; > @@ -2599,6 +2601,11 @@ 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) && laio_has_fdsync(s->fd)) { FDSYNC support should be probed at open() time and the result should be stored in a new bool field like s->laio_supports_fdsync. That way the cost of laio_has_fdsync() on every flush request is avoided. > + return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0); > + } > #endif > return raw_thread_pool_submit(handle_aiocb_flush, &acb); > } > diff --git a/block/linux-aio.c b/block/linux-aio.c > index ec05d946f3..ed20a503e9 100644 > --- a/block/linux-aio.c > +++ b/block/linux-aio.c > @@ -67,6 +67,7 @@ struct LinuxAioState { > int event_max; > }; > > +bool laio_has_fdsync(int); > static void ioq_submit(LinuxAioState *s); > > static inline ssize_t io_event_ret(struct io_event *ev) > @@ -384,6 +385,9 @@ 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 +416,7 @@ 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), > @@ -486,3 +490,19 @@ void laio_cleanup(LinuxAioState *s) > } > g_free(s); > } > + > +bool laio_has_fdsync(int fd) > +{ > + struct iocb cb; > + struct iocb *cbs[] = {&cb, NULL}; > + > + io_context_t ctx = 0; > + io_setup(1, &ctx); > + > + /* check if host kernel supports IO_CMD_FDSYNC */ > + io_prep_fdsync(&cb, fd); > + int ret = io_submit(ctx, 1, cbs); > + > + io_destroy(ctx); > + return (ret == -EINVAL) ? false : true; > +} > -- > 2.44.0 >
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