On 2010-12-02 19:59, Jens Axboe wrote: > On 2010-12-01 22:38, Sebastian Kayser wrote: >> Hi, >> >> I just stumbled into a glaring pitfall when playing with iodepth=X for >> the first time. Was using ioengine=sync (default), increased iodepth > 1 >> and wondered briefly why my results didn't change. Thinking about it, >> this made perfect sense and the "IO depths" distribution in the result >> summary even pointed me to it. >> >> Nevertheless, it might help others to avoid this alltogether if the man >> page paragraph on iodepth would include a small heads up / reference to >> ioengines. Example patch attached, not quite sure about the wording for >> the verify_async aspect. > > It's a good idea. Something else to keep in mind is that even with async > engines, you can run into this issue. Say in Linux and not setting > direct=1, the buffered IO will still be sync. So I think I'll add some > wording as well to have the user keep an eye on the achieved IO depths > and not just assume that it's running with a depth of X for iodepth=X. http://git.kernel.dk/?p=fio.git;a=commitdiff;h=ee72ca09d4657f6a805c113d9bc43428f4b28a89 -- 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
