NAME
   Devel::SmallProf - per-line Perl profiler

SYNOPSIS
           perl5 -d:SmallProf test.pl

DESCRIPTION
   The Devel::SmallProf profiler is focused on the time taken for a
   program run on a line-by-line basis. It is intended to be as
   "small" in terms of impact on the speed and memory usage of the
   profiled program as possible and also in terms of being simple
   to use. Those statistics are placed in the file smallprof.out in
   the following format:

           <num> <time> <file>:<line>:<text>

   where <num> is the number of times that the line was executed,
   <time> is the amount of time spent executing it and <file>,
   <line> and <text> are the filename, the line number and the
   actual text of the executed line (read from the file).

   The package uses the debugging hooks in Perl and thus needs the
   -d switch, so to profile test.pl, use the command:

           perl5 -d:SmallProf test.pl

   Once the script is done, the statistics in smallprof.out can be
   sorted to show which lines took the most time. The output can be
   sorted to find which lines take the longest, either with the
   sort command:

           sort -nrk 2 smallprof.out | less

   or a perl script:

           open(PROF,"smallprof.out");
           @sorted = sort {(split(/\s+/,$b))[2] <=>
                           (split(/\s+/,$a))[2]} <PROF>;
           close PROF;
           print join('',@sorted);

NOTES
   *   The timings are made with "wall time" (time in real life vs. cpu
       usage). I'd like eventually to report cpu time, but that
       isn't terribly easy to get across platforms.

   *   SmallProf does attempt to make up for its shortcomings by
       subtracting a small amount from each timing (null time
       compensation). This should help somewhat with the accuracy.

   *   SmallProf depends on the Time::HiRes package to do its timings
       except for the Win32 version which depends on Win32::API.

OPTIONS
   SmallProf has 3 variables which can be used during your script
   to affect what gets profiled.

   *   If you do not wish to see lines which were never called, set the
       variable `$DB::drop_zeros = 1'. With `drop_zeros' set,
       SmallProf can be used for basic coverage analysis.

   *   To turn off profiling for a time, insert a `$DB::profile = 0'
       into your code (profiling may be turned back on with
       `$DB::profile = 1'). All of the time between profiling being
       turned off and back on again will be lumped together and
       reported on the `$DB::profile = 0' line. This can be used to
       summarize a subroutine call or a chunk of code.

   *   To only profile code in a certain package, set the
       `%DB::packages' array. For example, to see only the code in
       packages `main' and `Test1', do this:

               %DB::packages = ( 'main' => 1, 'Test1' => 1 );

   *   These variables can be put in a file called .smallprof in the
       current directory. For example, a .smallprof containing

               $DB::drop_zeros = 1;
               $DB::profile = 0;

       will set SmallProf to not report lines which are never
       touched for any file profiled in that directory and will set
       profiling off initially (presumably to be turned on only for
       a small portion of code).

INSTALLATION
   Just the usual

           perl Makefile.PL
           make
           make test
           make install

   and should install fine via the CPAN module. Makefile.PL checks
   to see if this is a Win32 platform and runs a conversion
   subroutine on SmallProf prior to installation.

BUGS
   Subroutine calls are currently not under the control of
   %DB::packages. This should not be a great inconvenience in
   general.

   The handling of evals is bad news. This is due to Perl's
   handling of evals under the -d flag. For certain evals, caller()
   returns '(eval n)' for the filename and for others it doesn't.
   For some of those which it does, the array `@{'_<filename'}'
   contains the code of the eval. For others it doesn't. Sometime,
   when I've an extra tuit or two, I'll figure out why and how I
   can compensate for this.

   Comments, advice and questions are welcome. If you see
   inefficent stuff in this module and have a better way, please
   let me know.

AUTHOR

Ted Ashton <[email protected]>

SmallProf was developed from code originally posted to usenet by Philippe
Verdret <[email protected]>.  Special thanks to
Geoffrey Broadwell <[email protected]> for the Win32 code.

Copyright (c) 1997 Ted Ashton

This module is free software and can be redistributed and/or modified under the
same terms as Perl itself.
SEE ALSO
   the Devel::DProf manpage, the Time::HiRes manpage, the
   Win32::API manpage

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