The following changes since commit e55138eed3296b642229271b0dcec492ec776702: Merge branch 'evelu-enghelp' of https://github.com/ErwanAliasr1/fio into master (2020-09-09 10:48:27 -0600) are available in the Git repository at: git://git.kernel.dk/fio.git master for you to fetch changes up to 695611a9d4cd554d44d8b2ec5da2811061950a2e: Allow offload with FAKEIO engines (2020-09-11 09:58:15 -0600) ---------------------------------------------------------------- Jens Axboe (3): engines/io_uring: mark as not compatible with io_submit_mode=offload Disable io_submit_mode=offload with async engines Allow offload with FAKEIO engines HOWTO | 3 ++- engines/io_uring.c | 6 ++++++ fio.1 | 2 +- ioengines.c | 14 ++++++++++++-- 4 files changed, 21 insertions(+), 4 deletions(-) --- Diff of recent changes: diff --git a/HOWTO b/HOWTO index d8586723..2d8c7a02 100644 --- a/HOWTO +++ b/HOWTO @@ -2474,7 +2474,8 @@ I/O depth can increase latencies. The benefit is that fio can manage submission rates independently of the device completion rates. This avoids skewed latency reporting if I/O gets backed up on the device side (the coordinated omission - problem). + problem). Note that this option cannot reliably be used with async IO + engines. I/O rate diff --git a/engines/io_uring.c b/engines/io_uring.c index e2b5e6ee..69f48859 100644 --- a/engines/io_uring.c +++ b/engines/io_uring.c @@ -724,6 +724,12 @@ static int fio_ioring_init(struct thread_data *td) struct ioring_data *ld; struct thread_options *to = &td->o; + if (to->io_submit_mode == IO_MODE_OFFLOAD) { + log_err("fio: io_submit_mode=offload is not compatible (or " + "useful) with io_uring\n"); + return 1; + } + /* sqthread submission requires registered files */ if (o->sqpoll_thread) o->registerfiles = 1; diff --git a/fio.1 b/fio.1 index 74509bbd..a881277c 100644 --- a/fio.1 +++ b/fio.1 @@ -2215,7 +2215,7 @@ has a bit of extra overhead, especially for lower queue depth I/O where it can increase latencies. The benefit is that fio can manage submission rates independently of the device completion rates. This avoids skewed latency reporting if I/O gets backed up on the device side (the coordinated omission -problem). +problem). Note that this option cannot reliably be used with async IO engines. .SS "I/O rate" .TP .BI thinktime \fR=\fPtime diff --git a/ioengines.c b/ioengines.c index 476df58d..d3be8026 100644 --- a/ioengines.c +++ b/ioengines.c @@ -22,7 +22,7 @@ static FLIST_HEAD(engine_list); -static bool check_engine_ops(struct ioengine_ops *ops) +static bool check_engine_ops(struct thread_data *td, struct ioengine_ops *ops) { if (ops->version != FIO_IOOPS_VERSION) { log_err("bad ioops version %d (want %d)\n", ops->version, @@ -41,6 +41,16 @@ static bool check_engine_ops(struct ioengine_ops *ops) if (ops->flags & FIO_SYNCIO) return false; + /* + * async engines aren't reliable with offload + */ + if ((td->o.io_submit_mode == IO_MODE_OFFLOAD) && + !(ops->flags & FIO_FAKEIO)) { + log_err("%s: can't be used with offloaded submit. Use a sync " + "engine\n", ops->name); + return true; + } + if (!ops->event || !ops->getevents) { log_err("%s: no event/getevents handler\n", ops->name); return true; @@ -193,7 +203,7 @@ struct ioengine_ops *load_ioengine(struct thread_data *td) /* * Check that the required methods are there. */ - if (check_engine_ops(ops)) + if (check_engine_ops(td, ops)) return NULL; return ops;
