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
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
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,
if (ops->flags & FIO_SYNCIO)
return false;
+ /*
+ * async engines aren't reliable with offload
+ */
+ if (td->o.io_submit_mode == IO_MODE_OFFLOAD) {
+ 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;
/*
* Check that the required methods are there.
*/
- if (check_engine_ops(ops))
+ if (check_engine_ops(td, ops))
return NULL;
return ops;