On 8/2/19 5:09 AM, Richard W.M. Jones wrote: > libnbd also supports full asynchronous access. However I couldn't > work out how the ->getevents and ->event callbacks are supposed to > work in fio engines. If someone could take some time to explain to me > how those are supposed to be used then I could get a much higher > performance asynch engine working here. fio calls ->getevents() when it needs to get some completions. ->getevents() returns the number of events completed. If that number is 4, for instance, then fio will call ->event() with 0..3 to retrieve the io_u associated with each of those 4 completions. Also see engines/skeleton_external.c, it is pretty well commented. -- Jens Axboe
