Thanks Jens. I do in fact have an application that reads in exactly the manner I described. I have monitored the queue depth - it does not rise above 1. It is a real time musical sample streamer. Please consider this a new feature request for fio - thankyou. Greg. On Aug 14, 2012 11:06 PM, "Jens Axboe" <axboe@xxxxxxxxx> wrote: > > On 08/14/2012 08:24 AM, Greg Sullivan wrote: > > I need to simulate strict synchronous, round robin i/o to a group of > > files. I am on Windows 7 32-bit. > > fio is very nearly working, except that even with a queue depth of 1, > > it is still resulting in a disk queue that is > 1, because the > > "iodepth" parameter is not global - it is per thread. (correct?) > > > > I've tried using the "sync" engine, however that doesn't work at all - > > just spews out errors. > > That'll be the case for ANY platform and IO engine. If you have more > than 1 thread or process going, you can have > 1 depth at the device > side. The definition of a sync IO call is that the call doesn't return > until the IO is done. If you have overlapped calls due to more than 1 > thread, then that is no longer true. > > What you are looking for is outside the scope of an application. You > would have to limit the queue depth on the operating system side to > achieve that. Or artificially limit fio in some way, which would not > make a lot of sense imho. > > -- > 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
