Am Mittwoch, 3. August 2011 schrieb Martin Steigerwald: > Am Mittwoch, 3. August 2011 schrieben Sie: > > Martin Steigerwald <Martin@xxxxxxxxxxxx> writes: [...] > Does using iodepth > 1 need ioengine=libaio? Let´s see the manpage: > > iodepth=int > Number of I/O units to keep in flight against the > file. Note that increasing iodepth beyond 1 will > not affect synchronous ioengines (except for small > degress when verify_async is in use). Even async > engines my impose OS restrictions causing the > desired depth not to be achieved. This may happen > on Linux when using libaio and not setting > direct=1, since buffered IO is not async on that > OS. Keep an eye on the IO depth distribution in > the fio output to verify that the achieved depth > is as expected. Default: 1. > > Okay, yes, it does. I start getting a hang on it. Its a bit puzzling to > have two concepts of synchronous I/O around: > > 1) synchronous system call interfaces aka fio I/O engine > > 2) synchronous I/O requests aka O_SYNC But isn´t this a case for iodepth=1 if buffered I/O on Linux is synchronous? I bet most regular applications except some databases use buffered I/O. -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- 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
