=head1 NAME
-Benchmark - benchmark running times of code
-
-timethis - run a chunk of code several times
-
-timethese - run several chunks of code several times
-
-cmpthese - print results of timethese as a comparison chart
-
-timeit - run a chunk of code and see how long it goes
-
-countit - see how many times a chunk of code runs in a given time
+Benchmark - benchmark running times of Perl code
=head1 SYNOPSIS
+ use Benchmark qw(:all) ;
+
timethis ($count, "code");
# Use Perl code in strings...
The Benchmark module encapsulates a number of routines to help you
figure out how long it takes to execute some code.
+timethis - run a chunk of code several times
+
+timethese - run several chunks of code several times
+
+cmpthese - print results of timethese as a comparison chart
+
+timeit - run a chunk of code and see how long it goes
+
+countit - see how many times a chunk of code runs in a given time
+
+
=head2 Methods
=over 10
=item cmpthese ( COUT, CODEHASHREF, [ STYLE ] )
-=item cmpthese ( RESULTSHASHREF )
+=item cmpthese ( RESULTSHASHREF, [ STYLE ] )
+
+Optionally calls timethese(), then outputs comparison chart. This:
+
+ cmpthese( -1, { a => "++\$i", b => "\$i *= 2" } ) ;
+
+outputs a chart like:
+
+ Rate b a
+ b 2831802/s -- -61%
+ a 7208959/s 155% --
-Optionally calls timethese(), then outputs comparison chart. This
-chart is sorted from slowest to highest, and shows the percent
-speed difference between each pair of tests. Can also be passed
-the data structure that timethese() returns:
+This chart is sorted from slowest to fastest, and shows the percent speed
+difference between each pair of tests.
- $results = timethese( .... );
+c<cmpthese> can also be passed the data structure that timethese() returns:
+
+ $results = timethese( -1, { a => "++\$i", b => "\$i *= 2" } ) ;
cmpthese( $results );
-Returns the data structure returned by timethese().
+in case you want to see both sets of results.
+
+Returns a reference to an ARRAY of rows, each row is an ARRAY of cells from the
+above chart, including labels. This:
+
+ my $rows = cmpthese( -1, { a => '++$i', b => '$i *= 2' }, "none" );
+
+returns a data structure like:
+
+ [
+ [ '', 'Rate', 'b', 'a' ],
+ [ 'b', '2885232/s', '--', '-59%' ],
+ [ 'a', '7099126/s', '146%', '--' ],
+ ]
+
+B<NOTE>: This result value differs from previous versions, which returned
+the C<timethese()> result structure. If you want that, just use the two
+statement C<timethese>...C<cmpthese> idiom shown above.
+
+Incidently, note the variance in the result values between the two examples;
+this is typical of benchmarking. If this were a real benchmark, you would
+probably want to run a lot more iterations.
=item countit(TIME, CODE)
Caching is off by default, as it can (usually slightly) decrease
accuracy and does not usually noticably affect runtimes.
+=head1 EXAMPLES
+
+For example,
+
+ use Benchmark qw( cmpthese ) ;
+ $x = 3;
+ cmpthese( -5, {
+ a => sub{$x*$x},
+ b => sub{$x**2},
+ } );
+
+outputs something like this:
+
+ Benchmark: running a, b, each for at least 5 CPU seconds...
+ Rate b a
+ b 1559428/s -- -62%
+ a 4152037/s 166% --
+
+
+while
+
+ use Benchmark qw( timethese cmpthese ) ;
+ $x = 3;
+ $r = timethese( -5, {
+ a => sub{$x*$x},
+ b => sub{$x**2},
+ } );
+ cmpthese $r;
+
+outputs something like this:
+
+ Benchmark: running a, b, each for at least 5 CPU seconds...
+ a: 10 wallclock secs ( 5.14 usr + 0.13 sys = 5.27 CPU) @ 3835055.60/s (n=20210743)
+ b: 5 wallclock secs ( 5.41 usr + 0.00 sys = 5.41 CPU) @ 1574944.92/s (n=8520452)
+ Rate b a
+ b 1574945/s -- -59%
+ a 3835056/s 144% --
+
+
=head1 INHERITANCE
Benchmark inherits from no other class, except of course
more than the system time of the loop with the actual
code and therefore the difference might end up being E<lt> 0.
+=head1 SEE ALSO
+
+L<Devel::DProf> - a Perl code profiler
+
=head1 AUTHORS
Jarkko Hietaniemi <F<jhi@iki.fi>>, Tim Bunce <F<Tim.Bunce@ig.co.uk>>
efficiency tweaks. Added cmpthese(). A result is now returned from
timethese(). Exposed countit() (was runfor()).
+December, 2001; by Nicholas Clark: make timestr() recognise the style 'none'
+and return an empty string. If cmpthese is calling timethese, make it pass the
+style in. (so that 'none' will suppress output). Make sub new dump its
+debugging output to STDERR, to be consistent with everything else.
+All bugs found while writing a regression test.
+
=cut
# evaluate something in a clean lexical environment
@EXPORT=qw(timeit timethis timethese timediff timestr);
@EXPORT_OK=qw(timesum cmpthese countit
clearcache clearallcache disablecache enablecache);
+%EXPORT_TAGS=( all => [ @EXPORT, @EXPORT_OK ] ) ;
+
+$VERSION = 1.04;
&init;
# --- Functions to process the 'time' data type
sub new { my @t = (time, times, @_ == 2 ? $_[1] : 0);
- print "new=@t\n" if $debug;
+ print STDERR "new=@t\n" if $debug;
bless \@t; }
sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps ; }
my @t = @$tr;
warn "bad time value (@t)" unless @t==6;
my($r, $pu, $ps, $cu, $cs, $n) = @t;
- my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a);
+ my($pt, $ct, $tt) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a);
$f = $defaultfmt unless defined $f;
# format a time in the required style, other formats may be added here
$style ||= $defaultstyle;
+ return '' if $style eq 'none';
$style = ($ct>0) ? 'all' : 'noc' if $style eq 'auto';
my $s = "@t $style"; # default for unknown style
$s=sprintf("%2d wallclock secs (%$f usr %$f sys + %$f cusr %$f csys = %$f CPU)",
- @t,$t) if $style eq 'all';
+ $r,$pu,$ps,$cu,$cs,$tt) if $style eq 'all';
$s=sprintf("%2d wallclock secs (%$f usr + %$f sys = %$f CPU)",
$r,$pu,$ps,$pt) if $style eq 'noc';
$s=sprintf("%2d wallclock secs (%$f cusr + %$f csys = %$f CPU)",
$r,$cu,$cs,$ct) if $style eq 'nop';
- $s .= sprintf(" @ %$f/s (n=$n)", $n / ( $pu + $ps )) if $n;
+ $s .= sprintf(" @ %$f/s (n=$n)", $n / ( $pu + $ps )) if $n && $pu+$ps;
$s;
}
# in &countit. This, in turn, can reduce the number of calls to
# &runloop a lot, and thus reduce additive errors.
my $tbase = Benchmark->new(0)->[1];
- do {
- $t0 = Benchmark->new(0);
- } while ( $t0->[1] == $tbase );
+ while ( ( $t0 = Benchmark->new(0) )->[1] == $tbase ) {} ;
&$subref;
$t1 = Benchmark->new($n);
$td = &timediff($t1, $t0);
if ($cache && exists $cache{$cache_key} ) {
$wn = $cache{$cache_key};
} else {
- $wn = &runloop($n, ref( $code ) ? sub { undef } : '' );
+ $wn = &runloop($n, ref( $code ) ? sub { } : '' );
# Can't let our baseline have any iterations, or they get subtracted
# out of the result.
$wn->[5] = 0;
# accuracy since we're not couting these times.
$n = int( $tpra * 1.05 * $n / $tc ); # Linear approximation.
my $td = timeit($n, $code);
- $tc = $td->[1] + $td->[2];
+ my $new_tc = $td->[1] + $td->[2];
+ # Make sure we are making progress.
+ $tc = $new_tc > 1.2 * $tc ? $new_tc : 1.2 * $tc;
}
# Now, do the 'for real' timing(s), repeating until we exceed
$ttot = $utot + $stot;
last if $ttot >= $tmax;
+ $ttot = 0.01 if $ttot < 0.01;
my $r = $tmax / $ttot - 1; # Linear approximation.
$n = int( $r * $ntot );
$n = $nmin if $n < $nmin;
print " ", join(', ',@names) unless $style eq 'none';
unless ( $n > 0 ) {
my $for = n_to_for( $n );
- print ", each for at least $for CPU seconds" unless $style eq 'none';
+ print ", each" if $n > 1 && $style ne 'none';
+ print " for at least $for CPU seconds" unless $style eq 'none';
}
print "...\n" unless $style eq 'none';
}
sub cmpthese{
- my $results = ref $_[0] ? $_[0] : timethese( @_ );
+ my ($results, $style) = ref $_[0] ? @_ : ( timethese( @_[0,1,2] ), $_[2] ) ;
- return $results
- if defined $_[2] && $_[2] eq 'none';
+ $style = "" unless defined $style;
# Flatten in to an array of arrays with the name as the first field
my @vals = map{ [ $_, @{$results->{$_}} ] } keys %$results;
push @rows, \@row;
}
+ return \@rows if $style eq "none";
+
# Equalize column widths in the chart as much as possible without
# exceeding 80 characters. This does not use or affect cols 0 or 1.
my @sorted_width_refs =
sort { $$a <=> $$b } map { \$_ } @col_widths[2..$#col_widths];
my $max_width = ${$sorted_width_refs[-1]};
- my $total = 0;
+ my $total = @col_widths - 1 ;
for ( @col_widths ) { $total += $_ }
STRETCHER:
printf $format, @$_;
}
- return $results;
+ return \@rows ;
}
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