On 2011-07-14 04:49, Daniel Ehrenberg wrote: > Hi, > > I'm trying to recreate a workload which would call the io_getevents > function in Linux libaio without blocking, spinning until the result > comes up. There are two ways to make io_getevents return immediately > if there are no results: pass in a timeout of 0, or pass min_nr=0. (Of > course, this non-blocking way of invoking io_getevents wouldn't be > used by the cleanup routines, only during the main loop). I can't > figure out what the proper way to do this is. I don't see an option > that would allow this. I thought iodepth_batch_complete=0 would make > the min_nr be 0, but it seems that the minimum number in practice is > 1, as lines 555-556 establish. It looks like if > iodepth_batch_complete=0, then full might be false and min_nr might > not be set to 1, but this often isn't the case in my testing. I don't > see how to set a different timeout from the default, which seems to be > NULL. > > Am I missing something? What would be the proper way of allowing this > setting in a way that doesn't break other engines? One way I hacked up > is to make a new boolean option which sets min_events to 0 right after > line 556 if enabled (and similarly for the do_io main loop). Is there > a better way to do it? Otherwise, would you accept a patch that > implements this? I'd be fine with allowing the nonblocking/spinning variant if set explicitly. My only worry is people doing this by accident. But if iodepth_batch_complete was explicitly set to 0, then we should honor that. So I'll happily take a patch to modify that. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
