[perl5.git] / lib / Benchmark.pm

package Benchmark;

=head1 NAME

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

=head1 SYNOPSIS

    timethis ($count, "code");

    timethese($count, {
	'Name1' => '...code1...',
	'Name2' => '...code2...',
    });

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

=head1 DESCRIPTION

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

=head2 Methods

=over 10

=item new

Returns the current time.   Example:

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

=item debug

Enables or disable debugging by setting the C<$Benchmark::Debug> flag:

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

=back

=head2 Standard Exports

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

=over 10

=item timeit(COUNT, CODE)

Arguments: COUNT is the number of time to run the loop, and 
the second is the code to run.  CODE may be a string containing the code,
a reference to the function to run, or a reference to a hash containing 
keys which are names and values which are more CODE specs.

Side-effects: prints out noise to standard out.

Returns: a Benchmark object.  

=item timethis

=item timethese

=item timediff

=item timestr

=back

=head2 Optional Exports

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

=over 10

clearcache

clearallcache

disablecache

enablecache

=back

=head1 NOTES

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.

Enable debugging by:  

    $Benchmark::debug = 1;

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:

    clearcache($key); 
    clearallcache();

    disablecache(); 
    enablecache();

=head1 INHERITANCE

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

=head1 CAVEATS

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: 

    timethis(100,'1');

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.

More documentation is needed :-( especially for styles and formats.

=head1 AUTHORS

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

=head1 MODIFICATION HISTORY

September 8th, 1994; by Tim Bunce.

=cut

# Purpose: benchmark running times of code.
#
#
# Usage - to time code snippets and print results:
#
#	timethis($count, '...code...');
#		
# prints:
#	timethis 100:  2 secs ( 0.23 usr  0.10 sys =  0.33 cpu)
#
#
#	timethese($count, {
#		Name1 => '...code1...',
#		Name2 => '...code2...',
#		... });
# prints:
#	Benchmark: timing 100 iterations of Name1, Name2...
#	     Name1:  2 secs ( 0.50 usr  0.00 sys =  0.50 cpu)
#	     Name2:  1 secs ( 0.48 usr  0.00 sys =  0.48 cpu)
#
# The default display style will automatically add child process
# values if non-zero.
#
#
# Usage - to time sections of your own code:
#
#	use Benchmark;
#	$t0 = new Benchmark;
#	... your code here ...
#	$t1 = new Benchmark;
#	$td = &timediff($t1, $t0);
#	print "the code took:",timestr($td),"\n";
#
#	$t = &timeit($count, '...other code...')
#	print "$count loops of other code took:",timestr($t),"\n";
# 
#
# Data format:
#       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).
#		
# Internals:
#	The timing is done using time(3) and times(3).
#		
#	Code is executed in the callers package
#
#	Enable debugging by:  $Benchmark::debug = 1;
#
#	The time of the null loop (a loop with the same
#	number of rounds but empty loop body) is substracted
#	from the time of the real loop.
#
#	The null loop times are cached, the key being the
#	number of rounds. The caching can be controlled using
#	&clearcache($key); &clearallcache;
#	&disablecache; &enablecache;
#
# Caveats:
#
#	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 timethis(100,'1');
#
#	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
#
#	More documentation is needed :-(
#	Especially for styles and formats.
#
# Authors:	Jarkko Hietaniemi <Jarkko.Hietaniemi@hut.fi>
# 		Tim Bunce <Tim.Bunce@ig.co.uk>
#
#
# Last updated:	Sept 8th 94 by Tim Bunce
#

use Carp;
use Exporter;
@ISA=(Exporter);
@EXPORT=qw(timeit timethis timethese timediff timestr);
@EXPORT_OK=qw(clearcache clearallcache disablecache enablecache);

&init;

sub init {
    $debug = 0;
    $min_count = 4;
    $min_cpu   = 0.4;
    $defaultfmt = '5.2f';
    $defaultstyle = 'auto';
    # The cache can cause a slight loss of sys time accuracy. If a
    # user does many tests (>10) with *very* large counts (>10000)
    # or works on a very slow machine the cache may be useful.
    &disablecache;
    &clearallcache;
}

sub clearcache    { delete $cache{$_[0]}; }
sub clearallcache { %cache = (); }
sub enablecache   { $cache = 1; }
sub disablecache  { $cache = 0; }


# --- Functions to process the 'time' data type

sub new { my(@t)=(time, times); print "new=@t\n" if $debug; bless \@t; }

sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps         ; }
sub cpu_c { my($r,$pu,$ps,$cu,$cs) = @{$_[0]};         $cu+$cs ; }
sub cpu_a { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps+$cu+$cs ; }
sub real  { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $r              ; }

sub timediff{
    my($a, $b) = @_;
    my(@r);
    for($i=0; $i < @$a; ++$i){
	push(@r, $a->[$i] - $b->[$i]);
    }
    bless \@r;
}

sub timestr{
    my($tr, $style, $f) = @_;
    my(@t) = @$tr;
    warn "bad time value" unless @t==5;
    my($r, $pu, $ps, $cu, $cs) = @t;
    my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a);
    $f = $defaultfmt unless $f;
    # format a time in the required style, other formats may be added here
    $style = $defaultstyle unless $style;
    $style = ($ct>0) ? 'all' : 'noc' if $style=~/^auto$/;
    my($s) = "@t $style"; # default for unknown style
    $s=sprintf("%2d secs (%$f usr %$f sys + %$f cusr %$f csys = %$f cpu)",
			    @t,$t) if $style =~ /^all$/;
    $s=sprintf("%2d secs (%$f usr %$f sys = %$f cpu)",
			    $r,$pu,$ps,$pt) if $style =~ /^noc$/;
    $s=sprintf("%2d secs (%$f cusr %$f csys = %$f cpu)",
			    $r,$cu,$cs,$ct) if $style =~ /^nop$/;
    $s;
}
sub timedebug{
    my($msg, $t) = @_;
    print STDERR "$msg",timestr($t),"\n" if ($debug);
}


# --- Functions implementing low-level support for timing loops

sub runloop {
    my($n, $c) = @_;

    $n+=0; # force numeric now, so garbage won't creep into the eval
    croak "negativ loopcount $n" if $n<0;
    confess "Usage: runloop(number, string)" unless defined $c;
    my($t0, $t1, $td); # before, after, difference

    # find package of caller so we can execute code there
    my ($curpack) = caller(0);
    my ($i, $pack)= 0;
    while (($pack) = caller(++$i)) {
	last if $pack ne $curpack;
    }

    my $subcode = "sub { package $pack; my(\$_i)=$n; while (\$_i--){$c;} }";
    my $subref  = eval $subcode;
    croak "runloop unable to compile '$c': $@\ncode: $subcode\n" if $@;
    print STDERR "runloop $n '$subcode'\n" if ($debug);

    $t0 = &new;
    &$subref;
    $t1 = &new;
    $td = &timediff($t1, $t0);

    timedebug("runloop:",$td);
    $td;
}


sub timeit {
    my($n, $code) = @_;
    my($wn, $wc, $wd);

    printf STDERR "timeit $n $code\n" if $debug;

    if ($cache && exists $cache{$n}){
	$wn = $cache{$n};
    }else{
	$wn = &runloop($n, '');
	$cache{$n} = $wn;
    }

    $wc = &runloop($n, $code);

    $wd = timediff($wc, $wn);

    timedebug("timeit: ",$wc);
    timedebug("      - ",$wn);
    timedebug("      = ",$wd);

    $wd;
}


# --- Functions implementing high-level time-then-print utilities

sub timethis{
    my($n, $code, $title, $style) = @_;
    my($t) = timeit($n, $code);
    local($|) = 1;
    $title = "timethis $n" unless $title;
    $style = "" unless $style;
    printf("%10s: ", $title);
    print timestr($t, $style),"\n";
    # A conservative warning to spot very silly tests.
    # Don't assume that your benchmark is ok simply because
    # you don't get this warning!
    print "            (warning: too few iterations for a reliable count)\n"
	if (   $n < $min_count
	    || ($t->real < 1 && $n < 1000)
	    || $t->cpu_a < $min_cpu);
    $t;
}


sub timethese{
    my($n, $alt, $style) = @_;
    die "usage: timethese(count, { 'Name1'=>'code1', ... }\n"
		unless ref $alt eq HASH;
    my(@all);
    my(@names) = sort keys %$alt;
    $style = "" unless $style;
    print "Benchmark: timing $n iterations of ",join(', ',@names),"...\n";
    foreach(@names){
	$t = timethis($n, $alt->{$_}, $_, $style);
	push(@all, $t);
    }
    # we could produce a summary from @all here
    # sum, min, max, avg etc etc
    @all;
}


1;
Commit	Line	Data
a0d0e21e LW	1	package Benchmark;
a0d0e21e LW	2
f06db76b AD	3	=head1 NAME
	4
	5	Benchmark - benchmark running times of code
	6
	7	timethis - run a chunk of code several times
	8
	9	timethese - run several chunks of code several times
	10
	11	timeit - run a chunk of code and see how long it goes
	12
	13	=head1 SYNOPSIS
	14
	15	timethis ($count, "code");
	16
	17	timethese($count, {
	18	'Name1' => '...code1...',
	19	'Name2' => '...code2...',
	20	});
	21
	22	$t = timeit($count, '...other code...')
	23	print "$count loops of other code took:",timestr($t),"\n";
	24
	25	=head1 DESCRIPTION
	26
	27	The Benchmark module encapsulates a number of routines to help you
	28	figure out how long it takes to execute some code.
	29
	30	=head2 Methods
	31
	32	=over 10
	33
	34	=item new
	35
	36	Returns the current time. Example:
	37
	38	use Benchmark;
	39	$t0 = new Benchmark;
	40	# ... your code here ...
	41	$t1 = new Benchmark;
	42	$td = timediff($t1, $t0);
	43	print "the code took:",timestr($dt),"\n";
	44
	45	=item debug
	46
	47	Enables or disable debugging by setting the C<$Benchmark::Debug> flag:
	48
	49	debug Benchmark 1;
	50	$t = timeit(10, ' 5 ** $Global ');
	51	debug Benchmark 0;
	52
	53	=back
	54
	55	=head2 Standard Exports
	56
	57	The following routines will be exported into your namespace
	58	if you use the Benchmark module:
	59
	60	=over 10
	61
	62	=item timeit(COUNT, CODE)
	63
	64	Arguments: COUNT is the number of time to run the loop, and
	65	the second is the code to run. CODE may be a string containing the code,
	66	a reference to the function to run, or a reference to a hash containing
67	keys which are names and values which are more CODE specs.
68
69	Side-effects: prints out noise to standard out.
70
71	Returns: a Benchmark object.
72
73	=item timethis
74
75	=item timethese
76
77	=item timediff
78
79	=item timestr
80
81	=back
82
83	=head2 Optional Exports
84
85	The following routines will be exported into your namespace
86	if you specifically ask that they be imported:
87
88	=over 10
89
90	clearcache
91
92	clearallcache
93
94	disablecache
95
96	enablecache
97
98	=back
99
100	=head1 NOTES
101
102	The data is stored as a list of values from the time and times
103	functions:
104
105	($real, $user, $system, $children_user, $children_system)
106
107	in seconds for the whole loop (not divided by the number of rounds).
108
109	The timing is done using time(3) and times(3).
110
111	Code is executed in the caller's package.
112
113	Enable debugging by:
114
115	$Benchmark::debug = 1;
116
117	The time of the null loop (a loop with the same
118	number of rounds but empty loop body) is subtracted
119	from the time of the real loop.
120
121	The null loop times are cached, the key being the
122	number of rounds. The caching can be controlled using
123	calls like these:
124
125	clearcache($key);
126	clearallcache();
127
128	disablecache();
129	enablecache();
130
131	=head1 INHERITANCE
132
133	Benchmark inherits from no other class, except of course
134	for Exporter.
135
136	=head1 CAVEATS
137
138	The real time timing is done using time(2) and
139	the granularity is therefore only one second.
140
141	Short tests may produce negative figures because perl
142	can appear to take longer to execute the empty loop
143	than a short test; try:
144
145	timethis(100,'1');
146
147	The system time of the null loop might be slightly
148	more than the system time of the loop with the actual
149	code and therefore the difference might end up being < 0.
150
151	More documentation is needed :-( especially for styles and formats.
152
153	=head1 AUTHORS
154
155	Jarkko Hietaniemi <Jarkko.Hietaniemi@hut.fi>,
156	Tim Bunce <Tim.Bunce@ig.co.uk>
157
158	=head1 MODIFICATION HISTORY
159
160	September 8th, 1994; by Tim Bunce.
161
162	=cut
163
a0d0e21e LW	164	# Purpose: benchmark running times of code.
	165	#
	166	#
	167	# Usage - to time code snippets and print results:
	168	#
	169	# timethis($count, '...code...');
	170	#
	171	# prints:
	172	# timethis 100: 2 secs ( 0.23 usr 0.10 sys = 0.33 cpu)
	173	#
	174	#
	175	# timethese($count, {
	176	# Name1 => '...code1...',
	177	# Name2 => '...code2...',
	178	# ... });
	179	# prints:
	180	# Benchmark: timing 100 iterations of Name1, Name2...
	181	# Name1: 2 secs ( 0.50 usr 0.00 sys = 0.50 cpu)
	182	# Name2: 1 secs ( 0.48 usr 0.00 sys = 0.48 cpu)
	183	#
	184	# The default display style will automatically add child process
	185	# values if non-zero.
	186	#
	187	#
	188	# Usage - to time sections of your own code:
	189	#
	190	# use Benchmark;
	191	# $t0 = new Benchmark;
	192	# ... your code here ...
	193	# $t1 = new Benchmark;
	194	# $td = &timediff($t1, $t0);
	195	# print "the code took:",timestr($td),"\n";
	196	#
	197	# $t = &timeit($count, '...other code...')
	198	# print "$count loops of other code took:",timestr($t),"\n";
	199	#
	200	#
	201	# Data format:
	202	# The data is stored as a list of values from the time and times
	203	# functions: ($real, $user, $system, $children_user, $children_system)
	204	# in seconds for the whole loop (not divided by the number of rounds).
	205	#
	206	# Internals:
	207	# The timing is done using time(3) and times(3).
	208	#
	209	# Code is executed in the callers package
	210	#
	211	# Enable debugging by: $Benchmark::debug = 1;
	212	#
	213	# The time of the null loop (a loop with the same
	214	# number of rounds but empty loop body) is substracted
	215	# from the time of the real loop.
	216	#
	217	# The null loop times are cached, the key being the
	218	# number of rounds. The caching can be controlled using
	219	# &clearcache($key); &clearallcache;
	220	# &disablecache; &enablecache;
	221	#
	222	# Caveats:
	223	#
	224	# The real time timing is done using time(2) and
	225	# the granularity is therefore only one second.
	226	#
	227	# Short tests may produce negative figures because perl
228	# can appear to take longer to execute the empty loop
229	# than a short test: try timethis(100,'1');
230	#
231	# The system time of the null loop might be slightly
232	# more than the system time of the loop with the actual
233	# code and therefore the difference might end up being < 0
234	#
235	# More documentation is needed :-(
236	# Especially for styles and formats.
237	#
238	# Authors: Jarkko Hietaniemi <Jarkko.Hietaniemi@hut.fi>
239	# Tim Bunce <Tim.Bunce@ig.co.uk>
240	#
241	#
242	# Last updated: Sept 8th 94 by Tim Bunce
243	#
244
4aa0a1f7	245	use Carp;
a0d0e21e LW	246	use Exporter;
	247	@ISA=(Exporter);
	248	@EXPORT=qw(timeit timethis timethese timediff timestr);
	249	@EXPORT_OK=qw(clearcache clearallcache disablecache enablecache);
	250
	251	&init;
	252
	253	sub init {
	254	$debug = 0;
	255	$min_count = 4;
	256	$min_cpu = 0.4;
	257	$defaultfmt = '5.2f';
	258	$defaultstyle = 'auto';
	259	# The cache can cause a slight loss of sys time accuracy. If a
	260	# user does many tests (>10) with very large counts (>10000)
	261	# or works on a very slow machine the cache may be useful.
	262	&disablecache;
	263	&clearallcache;
	264	}
	265
	266	sub clearcache { delete $cache{$_[0]}; }
	267	sub clearallcache { %cache = (); }
	268	sub enablecache { $cache = 1; }
	269	sub disablecache { $cache = 0; }
	270
	271
	272	# --- Functions to process the 'time' data type
	273
	274	sub new { my(@t)=(time, times); print "new=@t\n" if $debug; bless \@t; }
	275
	276	sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps ; }
	277	sub cpu_c { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $cu+$cs ; }
	278	sub cpu_a { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps+$cu+$cs ; }
	279	sub real { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $r ; }
	280
	281	sub timediff{
	282	my($a, $b) = @_;
	283	my(@r);
	284	for($i=0; $i < @$a; ++$i){
	285	push(@r, $a->[$i] - $b->[$i]);
	286	}
	287	bless \@r;
	288	}
	289
	290	sub timestr{
	291	my($tr, $style, $f) = @_;
	292	my(@t) = @$tr;
	293	warn "bad time value" unless @t==5;
	294	my($r, $pu, $ps, $cu, $cs) = @t;
	295	my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a);
	296	$f = $defaultfmt unless $f;
	297	# format a time in the required style, other formats may be added here
	298	$style = $defaultstyle unless $style;
	299	$style = ($ct>0) ? 'all' : 'noc' if $style=~/^auto$/;
	300	my($s) = "@t $style"; # default for unknown style
	301	$s=sprintf("%2d secs (%$f usr %$f sys + %$f cusr %$f csys = %$f cpu)",
	302	@t,$t) if $style =~ /^all$/;
	303	$s=sprintf("%2d secs (%$f usr %$f sys = %$f cpu)",
	304	$r,$pu,$ps,$pt) if $style =~ /^noc$/;
	305	$s=sprintf("%2d secs (%$f cusr %$f csys = %$f cpu)",
	306	$r,$cu,$cs,$ct) if $style =~ /^nop$/;
	307	$s;
	308	}
	309	sub timedebug{
310	my($msg, $t) = @_;
311	print STDERR "$msg",timestr($t),"\n" if ($debug);
312	}
313
314
315	# --- Functions implementing low-level support for timing loops
316
317	sub runloop {
318	my($n, $c) = @_;
4aa0a1f7 AD	319
	320	$n+=0; # force numeric now, so garbage won't creep into the eval
	321	croak "negativ loopcount $n" if $n<0;
	322	confess "Usage: runloop(number, string)" unless defined $c;
a0d0e21e LW	323	my($t0, $t1, $td); # before, after, difference
	324
	325	# find package of caller so we can execute code there
	326	my ($curpack) = caller(0);
	327	my ($i, $pack)= 0;
	328	while (($pack) = caller(++$i)) {
	329	last if $pack ne $curpack;
	330	}
	331
	332	my $subcode = "sub { package $pack; my(\$_i)=$n; while (\$_i--){$c;} }";
	333	my $subref = eval $subcode;
4aa0a1f7	334	croak "runloop unable to compile '$c': $@\ncode: $subcode\n" if $@;
a0d0e21e LW	335	print STDERR "runloop $n '$subcode'\n" if ($debug);
	336
	337	$t0 = &new;
	338	&$subref;
	339	$t1 = &new;
	340	$td = &timediff($t1, $t0);
	341
	342	timedebug("runloop:",$td);
	343	$td;
	344	}
	345
	346
	347	sub timeit {
	348	my($n, $code) = @_;
	349	my($wn, $wc, $wd);
	350
	351	printf STDERR "timeit $n $code\n" if $debug;
	352
	353	if ($cache && exists $cache{$n}){
	354	$wn = $cache{$n};
	355	}else{
	356	$wn = &runloop($n, '');
	357	$cache{$n} = $wn;
	358	}
	359
	360	$wc = &runloop($n, $code);
	361
	362	$wd = timediff($wc, $wn);
	363
	364	timedebug("timeit: ",$wc);
	365	timedebug(" - ",$wn);
	366	timedebug(" = ",$wd);
	367
	368	$wd;
	369	}
	370
	371
	372	# --- Functions implementing high-level time-then-print utilities
	373
	374	sub timethis{
	375	my($n, $code, $title, $style) = @_;
	376	my($t) = timeit($n, $code);
	377	local($\|) = 1;
	378	$title = "timethis $n" unless $title;
	379	$style = "" unless $style;
	380	printf("%10s: ", $title);
	381	print timestr($t, $style),"\n";
	382	# A conservative warning to spot very silly tests.
	383	# Don't assume that your benchmark is ok simply because
	384	# you don't get this warning!
	385	print " (warning: too few iterations for a reliable count)\n"
	386	if ( $n < $min_count
	387	\|\| ($t->real < 1 && $n < 1000)
	388	\|\| $t->cpu_a < $min_cpu);
	389	$t;
	390	}
	391
	392
	393	sub timethese{
	394	my($n, $alt, $style) = @_;
	395	die "usage: timethese(count, { 'Name1'=>'code1', ... }\n"
	396	unless ref $alt eq HASH;
	397	my(@all);
	398	my(@names) = sort keys %$alt;
399	$style = "" unless $style;
400	print "Benchmark: timing $n iterations of ",join(', ',@names),"...\n";
401	foreach(@names){
402	$t = timethis($n, $alt->{$_}, $_, $style);
403	push(@all, $t);
404	}
405	# we could produce a summary from @all here
406	# sum, min, max, avg etc etc
407	@all;
408	}
409
410
411	1;