*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->IRIX man pages -> perl5/Benchmark (3)              


Benchmark(3)							  Benchmark(3)

NAME    [Toc]    [Back]

     Benchmark - benchmark running times of code

     timethis -	run a chunk of code several times

     timethese - run several chunks of code several times

     timeit - run a chunk of code and see how long it goes

SYNOPSIS    [Toc]    [Back]

	 timethis ($count, "code");

	 # Use Perl code in strings...
	 timethese($count, {
	     'Name1' =>	'...code1...',
	     'Name2' =>	'...code2...',

	 # ... or use subroutine references.
	 timethese($count, {
	     'Name1' =>	sub { ...code1... },
	     'Name2' =>	sub { ...code2... },

	 $t = timeit($count, '...other code...')
	 print "$count loops of	other code took:",timestr($t),"\n";

DESCRIPTION    [Toc]    [Back]

     The Benchmark module encapsulates a number	of routines to help you	figure
     out how long it takes to execute some code.

     Methods    [Toc]    [Back]

     new       Returns the current time.   Example:

		   use Benchmark;
		   $t0 = new Benchmark;
		   # ... your code here	...
		   $t1 = new Benchmark;
		   $td = timediff($t1, $t0);
		   print "the code took:",timestr($td),"\n";

     debug     Enables or disable debugging by setting the $Benchmark::Debug

		   debug Benchmark 1;
		   $t =	timeit(10, ' 5 ** $Global ');
		   debug Benchmark 0;

									Page 1

Benchmark(3)							  Benchmark(3)

     Standard Exports    [Toc]    [Back]

     The following routines will be exported into your namespace if you	use
     the Benchmark module:

     timeit(COUNT, CODE)
	       Arguments: COUNT	is the number of times to run the loop,	and
	       CODE is the code	to run.	 CODE may be either a code reference
	       or a string to be eval'd; either	way it will be run in the
	       caller's	package.

	       Returns:	a Benchmark object.

     timethis (	COUNT, CODE, [ TITLE, [	STYLE ]] )
	       Time COUNT iterations of	CODE. CODE may be a string to eval or
	       a code reference; either	way the	CODE will run in the caller's
	       package.	 Results will be printed to STDOUT as TITLE followed
	       by the times.  TITLE defaults to	"timethis COUNT" if none is
	       provided. STYLE determines the format of	the output, as
	       described for timestr() below.

     timethese ( COUNT,	CODEHASHREF, [ STYLE ] )
	       The CODEHASHREF is a reference to a hash	containing names as
	       keys and	either a string	to eval	or a code reference for	each
	       value.  For each	(KEY, VALUE) pair in the CODEHASHREF, this
	       routine will call

		       timethis(COUNT, VALUE, KEY, STYLE)

     timediff (	T1, T2 )
	       Returns the difference between two Benchmark times as a
	       Benchmark object	suitable for passing to	timestr().

     timestr ( TIMEDIFF, [ STYLE, [ FORMAT ]] )
	       Returns a string	that formats the times in the TIMEDIFF object
	       in the requested	STYLE. TIMEDIFF	is expected to be a Benchmark
	       object similar to that returned by timediff().

	       STYLE can be any	of 'all', 'noc', 'nop' or 'auto'. 'all'	shows
	       each of the 5 times available ('wallclock' time,	user time,
	       system time, user time of children, and system time of
	       children). 'noc'	shows all except the two children times. 'nop'
	       shows only wallclock and	the two	children times.	'auto' (the
	       default)	will act as 'all' unless the children times are	both
	       zero, in	which case it acts as 'noc'.

	       FORMAT is the the printf(3) manpage-style format	specifier
	       (without	the leading '%') to use	to print the times. It
	       defaults	to '5.2f'.

									Page 2

Benchmark(3)							  Benchmark(3)

     Optional Exports    [Toc]    [Back]

     The following routines will be exported into your namespace if you
     specifically ask that they	be imported:

     clearcache	( COUNT	)
	       Clear the cached	time for COUNT rounds of the null loop.

     clearallcache ( )
	       Clear all cached	times.

     disablecache ( )
	       Disable caching of timings for the null loop. This will force
	       Benchmark to recalculate	these timings for each new piece of
	       code timed.

     enablecache ( )
	       Enable caching of timings for the null loop. The	time taken for
	       COUNT rounds of the null	loop will be calculated	only once for
	       each different COUNT used.

NOTES    [Toc]    [Back]

     The data is stored	as a list of values from the time and times functions:

	   ($real, $user, $system, $children_user, $children_system)

     in	seconds	for the	whole loop (not	divided	by the number of rounds).

     The timing	is done	using time(3) and times(3).

     Code is executed in the caller's package.

     The time of the null loop (a loop with the	same number of rounds but
     empty loop	body) is subtracted from the time of the real loop.

     The null loop times are cached, the key being the number of rounds. The
     caching can be controlled using calls like	these:



INHERITANCE    [Toc]    [Back]

     Benchmark inherits	from no	other class, except of course for Exporter.

CAVEATS    [Toc]    [Back]

     Comparing eval'd strings with code	references will	give you inaccurate
     results: a	code reference will show a slower execution time than the
     equivalent	eval'd string.

									Page 3

Benchmark(3)							  Benchmark(3)

     The real time timing is done using	time(2)	and the	granularity is
     therefore only one	second.

     Short tests may produce negative figures because perl can appear to take
     longer to execute the empty loop than a short test; try:


     The system	time of	the null loop might be slightly	more than the system
     time of the loop with the actual code and therefore the difference	might
     end up being < 0.

AUTHORS    [Toc]    [Back]

     Jarkko Hietaniemi <jhi@iki.fi>, Tim Bunce <Tim.Bunce@ig.co.uk>


     September 8th, 1994; by Tim Bunce.

     March 28th, 1997; by Hugo van der Sanden: added support for code
     references	and the	already	documented 'debug' method; revamped

									PPPPaaaaggggeeee 4444
[ Back ]
 Similar pages
Name OS Title
sconv HP-UX hp9000 utility for Simplified-Chinese code code-converter
dmFS1016Encode IRIX implements the US Federal Standard 1016 4800/7200/9600 bits/s CELP (Code Excited Linear Predictive) Voice Code
dmFS1016Decode IRIX implements the US Federal Standard 1016 4800/7200/9600 bits/s CELP (Code Excited Linear Predictive) Voice Code
xsubpp OpenBSD compiler to convert Perl XS code into C code
xsubpp IRIX compiler to convert Perl XS code into C code
coco Tru64 code converter for any of Mule's code
pxftimes IRIX Gets process times
times FreeBSD process times
utime FreeBSD set file times
times OpenBSD process times
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service