This program can be used for generating file I/O and measuring the performance. The block size and file size can be varied and mixed in different ways, including performing the same task sequence multiple times (-c).
These are some of the options supported by iogen (dump from version 1.0.1):
Usage: src/iogen [options..] Options: -f,--file=name: The output file name. -s,--size=bytes: The number of bytes to write (104857600). -b,--block=size: Number of bytes to write at once (8192). -p,--pad=size: Write size bytes to file before starting measure timers. -c,--count=num: Number of iterations (1). -m,--multi=type: Enable multi mode. The type value is either seq or mix. -t,--timer: Collect timing statistics. -r,--report=type: Set report type. The type value is either tab, csv, xml or human. ...
The -s argument should be set to a sufficient large value when measuring true disk I/O performance to minimize effects of the file system cache.