lat_mmap(8) costs of mmapping and unmmapping varying file sizes


lat_mmap [ -P <parallelism> ] [ -W <warmups> ] [ -N <repetitions> ] size file


lat_mmap times how fast a mapping can be made and unmade. This is useful because it is a fundamental part of processes that use SunOS style shared libraries (the libraries are mapped in at process start up time and unmapped at process exit).

The benchmark maps in and unmaps the first size bytes of the file repeatedly and reports the average time for one mapping/unmapping.

The size specification may end with ``k'' or ``m'' to mean kilobytes (* 1024) or megabytes (* 1024 * 1024).


Output format is "%0.2f %d\n", megabytes, usecs, i.e.,

8.00 1200


Funding for the development of this tool was provided by Sun Microsystems Computer Corporation.


Carl Staelin and Larry McVoy

Comments, suggestions, and bug reports are always welcome.