Jens Axboe <ax...@kernel.dk> writes: > On 03/19/2015 11:34 AM, Tejun Heo wrote: >> Hello, >> >> So, Jens noticed that fio process exiting takes seconds when there are >> multiple aio contexts and the culprit seems to be the serial >> percpu_ref draining in exit_aio(). It's generally a bad idea to >> expose RCU latencies to userland because they add up really quickly >> and are unrelated to other performance parameters. Can you guys >> please at least update the code so that it waits for all percpu_refs >> to drain at the same time rather than one after another? That should >> resolve the worst part of the problem. > > This works for me. Before: > > real 0m5.872s > user 0m0.020s > sys 0m0.040s > > after > > real 0m0.246s > user 0m0.020s > sys 0m0.040s > > It solves the exit_aio() issue, but if the app calls io_destroy(), > then we are back to square one...
Do you really want to do memory allocation in the exit path? That sounds like a bad idea to me. (Of course, now you're going to point out all the places that currently happens, right? ;-) -Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
