PROFILING(7)       FreeBSD Miscellaneous Information Manual       PROFILING(7)

NAME
     profiling - kernel profiling under FreeBSD

WHAT IS PROFILING?
     Profiling is a technique to determine how much time a routine or part of
     a routine consumes.  It can help in analysing:

     o         Why some routine perform's poorly, i.e. if it needs a rewrite
               or a cleanup, thus improving execution speed.

     o         If a routine is not being called more or less than your expec-
               tation.  This information can be useful to fix bugs that are
               hard to notice.

     Kernel profiling can help in optimizing or fixing bugs in  a particular
     subsystem.  There are various methods of profiling code, but only two are
     discussed in this manual page:

         Execution Profiling
         A method of accounting the running time of called routines in the
         running time that called them. [1] This technique can be used to com-
         pare implementations of a particular routine / subsystem, or to tune
         the amount of CPU time spent.

         Basic Block Profiling
         A method of accounting how many times a basic block in a program
         (part of the kernel in our case) has executed.  Basic blocks are
         series of program instructions which do not perform external opera-
         tions, thus providing us with an accurate account of how many times
         each of the instructions were executed.  This technique is also known
         as block counting.

EXECUTION PROFILING
     TODO.  Add info on what execution profiling is actually good for; how to
     use it in FreeBSD, and stuff like that.

BASIC BLOCK PROFILING
     Provide brief description, and information on what bb profiling is good
     for; how to use it on FreeBSD ( information provided by phk@ )

TODO
     Using the profil(2) interface

     Simple introduction to gprof(1) and kgmon(8)

     Using kernbb(8)

     HISTORY section

SEE ALSO
     gprof(1), kgmon(8), kernbb(8), profil(2)

     [grahan82gprof] - "gprof: a Call Graph Execution Profiler" by Susan L.
     Graham and Peter B. Kessler and Marshall K. McKusick. (1982)

AUTHORS
     This manual page is written by Hiten Pandya and Poul-Henning Kemp.

FreeBSD 5.0                    December, 6, 2003                   FreeBSD 5.0