man/io_uring_setup.2: add note on IOPOLL and storage devices
Also include a hint on the appropriate parameter for NVMe devices.
@@ -71,6 +71,14 @@ application must poll for completions on the CQ ring by calling
It is illegal to mix and match polled and non-polled I/O on an io_uring
instance.
+This is only applicable for storage devices for now, and the storage device
+must be configured for polling. How to do that depends on the device type
+in question. For NVMe devices, the nvme driver must be loaded with the
+.I poll_queues
+parameter set to the desired number of polling queues. The polling queues
+will be shared appropriately between the CPUs in the system, if the number
+is less than the number of online CPU threads.
+
.TP
.B IORING_SETUP_SQPOLL
When this flag is specified, a kernel thread is created to perform
