diff options
| author | Prasad Pandit <pjp@fedoraproject.org> | 2024-04-25 12:34:12 +0530 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2024-06-10 11:05:43 +0200 |
| commit | 24687abf237e3c15816d689a8e4b08d7c3190dcb (patch) | |
| tree | a5f88ac731a9dbce536a46a866549830bf950e87 /block | |
| parent | 10b1e09ed3c40baf9fe074e0c70a7a3b783839ff (diff) | |
linux-aio: add IO_CMD_FDSYNC command support
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.
When using aio=native without fdsync() support, QEMU creates
pthreads, and destroying these pthreads results in TLB flushes.
In a real-time guest environment, TLB flushes cause a latency
spike. This patch helps to avoid such spikes.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
Message-ID: <20240425070412.37248-1-ppandit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/file-posix.c | 9 | ||||
| -rw-r--r-- | block/linux-aio.c | 21 |
2 files changed, 29 insertions, 1 deletions
diff --git a/block/file-posix.c b/block/file-posix.c index 5c46938936..be25e35ff6 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -159,6 +159,7 @@ typedef struct BDRVRawState { bool has_discard:1; bool has_write_zeroes:1; bool use_linux_aio:1; + bool has_laio_fdsync:1; bool use_linux_io_uring:1; int page_cache_inconsistent; /* errno from fdatasync failure */ bool has_fallocate; @@ -718,6 +719,9 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, ret = -EINVAL; goto fail; } + if (s->use_linux_aio) { + s->has_laio_fdsync = laio_has_fdsync(s->fd); + } #else if (s->use_linux_aio) { error_setg(errp, "aio=native was specified, but is not supported " @@ -2599,6 +2603,11 @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs) return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH); } #endif +#ifdef CONFIG_LINUX_AIO + if (s->has_laio_fdsync && raw_check_linux_aio(s)) { + 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..e3b5ec9aba 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), @@ -486,3 +489,19 @@ 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; +} |