package Benchmark;
-=head1 NAME
-
-Benchmark - benchmark running times of code
+use strict;
-timethis - run a chunk of code several times
-timethese - run several chunks of code several times
+=head1 NAME
-timeit - run a chunk of code and see how long it goes
+Benchmark - benchmark running times of Perl code
=head1 SYNOPSIS
+ use Benchmark qw(:all) ;
+
timethis ($count, "code");
# Use Perl code in strings...
'Name2' => sub { ...code2... },
});
+ # cmpthese can be used both ways as well
+ cmpthese($count, {
+ 'Name1' => '...code1...',
+ 'Name2' => '...code2...',
+ });
+
+ cmpthese($count, {
+ 'Name1' => sub { ...code1... },
+ 'Name2' => sub { ...code2... },
+ });
+
+ # ...or in two stages
+ $results = timethese($count,
+ {
+ 'Name1' => sub { ...code1... },
+ 'Name2' => sub { ...code2... },
+ },
+ 'none'
+ );
+ cmpthese( $results ) ;
+
$t = timeit($count, '...other code...')
print "$count loops of other code took:",timestr($t),"\n";
+ $t = countit($time, '...other code...')
+ $count = $t->iters ;
+ print "$count loops of other code took:",timestr($t),"\n";
+
+ # enable hires wallclock timing if possible
+ use Benchmark ':hireswallclock';
+
=head1 DESCRIPTION
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
Returns the current time. Example:
use Benchmark;
- $t0 = new Benchmark;
+ $t0 = Benchmark->new;
# ... your code here ...
- $t1 = new Benchmark;
+ $t1 = Benchmark->new;
$td = timediff($t1, $t0);
print "the code took:",timestr($td),"\n";
Enables or disable debugging by setting the C<$Benchmark::Debug> flag:
- debug Benchmark 1;
+ Benchmark->debug(1);
$t = timeit(10, ' 5 ** $Global ');
- debug Benchmark 0;
+ Benchmark->debug(0);
+
+=item iters
+
+Returns the number of iterations.
=back
TITLE defaults to "timethis COUNT" if none is provided. STYLE
determines the format of the output, as described for timestr() below.
+The COUNT can be zero or negative: this means the I<minimum number of
+CPU seconds> to run. A zero signifies the default of 3 seconds. For
+example to run at least for 10 seconds:
+
+ timethis(-10, $code)
+
+or to run two pieces of code tests for at least 3 seconds:
+
+ timethese(0, { test1 => '...', test2 => '...'})
+
+CPU seconds is, in UNIX terms, the user time plus the system time of
+the process itself, as opposed to the real (wallclock) time and the
+time spent by the child processes. Less than 0.1 seconds is not
+accepted (-0.01 as the count, for example, will cause a fatal runtime
+exception).
+
+Note that the CPU seconds is the B<minimum> time: CPU scheduling and
+other operating system factors may complicate the attempt so that a
+little bit more time is spent. The benchmark output will, however,
+also tell the number of C<$code> runs/second, which should be a more
+interesting number than the actually spent seconds.
+
+Returns a Benchmark object.
+
=item timethese ( COUNT, CODEHASHREF, [ STYLE ] )
The CODEHASHREF is a reference to a hash containing names as keys
timethis(COUNT, VALUE, KEY, STYLE)
+The routines are called in string comparison order of KEY.
+
+The COUNT can be zero or negative, see timethis().
+
+Returns a hash reference of Benchmark objects, keyed by name.
+
=item timediff ( T1, T2 )
Returns the difference between two Benchmark times as a Benchmark
object suitable for passing to timestr().
-=item timestr ( TIMEDIFF, [ STYLE, [ FORMAT ]] )
+=item 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,
+STYLE can be any of 'all', 'none', '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'.
+'none' prevents output.
FORMAT is the L<printf(3)>-style format specifier (without the
leading '%') to use to print the times. It defaults to '5.2f'.
Clear all cached times.
+=item cmpthese ( COUNT, CODEHASHREF, [ STYLE ] )
+
+=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% --
+
+This chart is sorted from slowest to fastest, and shows the percent speed
+difference between each pair of tests.
+
+C<cmpthese> can also be passed the data structure that timethese() returns:
+
+ $results = timethese( -1,
+ { a => "++\$i", b => "\$i *= 2" } ) ;
+ cmpthese( $results );
+
+in case you want to see both sets of results.
+If the first argument is an unblessed hash reference,
+that is RESULTSHASHREF; otherwise that is COUNT.
+
+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.
+
+Incidentally, 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)
+
+Arguments: TIME is the minimum length of time to run CODE for, 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.
+
+TIME is I<not> negative. countit() will run the loop many times to
+calculate the speed of CODE before running it for TIME. The actual
+time run for will usually be greater than TIME due to system clock
+resolution, so it's best to look at the number of iterations divided
+by the times that you are concerned with, not just the iterations.
+
+Returns: a Benchmark object.
+
=item disablecache ( )
Disable caching of timings for the null loop. This will force Benchmark
rounds of the null loop will be calculated only once for each
different COUNT used.
+=item timesum ( T1, T2 )
+
+Returns the sum of two Benchmark times as a Benchmark object suitable
+for passing to timestr().
+
+=back
+
+=head2 :hireswallclock
+
+If the Time::HiRes module has been installed, you can specify the
+special tag C<:hireswallclock> for Benchmark (if Time::HiRes is not
+available, the tag will be silently ignored). This tag will cause the
+wallclock time to be measured in microseconds, instead of integer
+seconds. Note though that the speed computations are still conducted
+in CPU time, not wallclock time.
+
+=head1 Benchmark Object
+
+Many of the functions in this module return a Benchmark object,
+or in the case of C<timethese()>, a reference to a hash, the values of
+which are Benchmark objects. This is useful if you want to store or
+further process results from Benchmark functions.
+
+Internally the Benchmark object holds timing values,
+described in L</"NOTES"> below.
+The following methods can be used to access them:
+
+=over 4
+
+=item cpu_p
+
+Total CPU (User + System) of the main (parent) process.
+
+=item cpu_c
+
+Total CPU (User + System) of any children processes.
+
+=item cpu_a
+
+Total CPU of parent and any children processes.
+
+=item real
+
+Real elapsed time "wallclock seconds".
+
+=item iters
+
+Number of iterations run.
+
=back
+The following illustrates use of the Benchmark object:
+
+ $result = timethis(100000, sub { ... });
+ print "total CPU = ", $result->cpu_a, "\n";
+
=head1 NOTES
The data is stored as a list of values from the time and times
functions:
- ($real, $user, $system, $children_user, $children_system)
+ ($real, $user, $system, $children_user, $children_system, $iters)
in seconds for the whole loop (not divided by the number of rounds).
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
+The null loop times can be cached, the key being the
number of rounds. The caching can be controlled using
calls like these:
disablecache();
enablecache();
+Caching is off by default, as it can (usually slightly) decrease
+accuracy and does not usually noticeably 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
-for Exporter.
+from Exporter.
=head1 CAVEATS
Comparing eval'd strings with code references will give you
-inaccurate results: a code reference will show a slower
+inaccurate results: a code reference will show a slightly slower
execution time than the equivalent eval'd string.
The real time timing is done using time(2) and
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::NYTProf> - a Perl code profiler
+
=head1 AUTHORS
Jarkko Hietaniemi <F<jhi@iki.fi>>, Tim Bunce <F<Tim.Bunce@ig.co.uk>>
references and the already documented 'debug' method; revamped
documentation.
+April 04-07th, 1997: by Jarkko Hietaniemi, added the run-for-some-time
+functionality.
+
+September, 1999; by Barrie Slaymaker: math fixes and accuracy and
+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.
+
+September, 2002; by Jarkko Hietaniemi: add ':hireswallclock' special tag.
+
+February, 2004; by Chia-liang Kao: make cmpthese and timestr use time
+statistics for children instead of parent when the style is 'nop'.
+
+November, 2007; by Christophe Grosjean: make cmpthese and timestr compute
+time consistently with style argument, default is 'all' not 'noc' any more.
+
=cut
+# evaluate something in a clean lexical environment
+sub _doeval { no strict; eval shift }
+
+#
+# put any lexicals at file scope AFTER here
+#
+
use Carp;
use Exporter;
-@ISA=(Exporter);
+
+our(@ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS, $VERSION);
+
+@ISA=qw(Exporter);
@EXPORT=qw(timeit timethis timethese timediff timestr);
-@EXPORT_OK=qw(clearcache clearallcache disablecache enablecache);
+@EXPORT_OK=qw(timesum cmpthese countit
+ clearcache clearallcache disablecache enablecache);
+%EXPORT_TAGS=( all => [ @EXPORT, @EXPORT_OK ] ) ;
+
+$VERSION = 1.23;
-&init;
+# --- ':hireswallclock' special handling
+
+my $hirestime;
+
+sub mytime () { time }
+
+init();
+
+sub BEGIN {
+ if (eval 'require Time::HiRes') {
+ import Time::HiRes qw(time);
+ $hirestime = \&Time::HiRes::time;
+ }
+}
+
+sub import {
+ my $class = shift;
+ if (grep { $_ eq ":hireswallclock" } @_) {
+ @_ = grep { $_ ne ":hireswallclock" } @_;
+ local $^W=0;
+ *mytime = $hirestime if defined $hirestime;
+ }
+ Benchmark->export_to_level(1, $class, @_);
+}
+
+our($Debug, $Min_Count, $Min_CPU, $Default_Format, $Default_Style,
+ %_Usage, %Cache, $Do_Cache);
sub init {
- $debug = 0;
- $min_count = 4;
- $min_cpu = 0.4;
- $defaultfmt = '5.2f';
- $defaultstyle = 'auto';
+ $Debug = 0;
+ $Min_Count = 4;
+ $Min_CPU = 0.4;
+ $Default_Format = '5.2f';
+ $Default_Style = '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;
+ disablecache();
+ clearallcache();
+}
+
+sub debug { $Debug = ($_[1] != 0); }
+
+sub usage {
+ my $calling_sub = (caller(1))[3];
+ $calling_sub =~ s/^Benchmark:://;
+ return $_Usage{$calling_sub} || '';
+}
+
+# The cache needs two branches: 's' for strings and 'c' for code. The
+# empty loop is different in these two cases.
+
+$_Usage{clearcache} = <<'USAGE';
+usage: clearcache($count);
+USAGE
+
+sub clearcache {
+ die usage unless @_ == 1;
+ delete $Cache{"$_[0]c"}; delete $Cache{"$_[0]s"};
+}
+
+$_Usage{clearallcache} = <<'USAGE';
+usage: clearallcache();
+USAGE
+
+sub clearallcache {
+ die usage if @_;
+ %Cache = ();
}
-sub debug { $debug = ($_[1] != 0); }
+$_Usage{enablecache} = <<'USAGE';
+usage: enablecache();
+USAGE
+
+sub enablecache {
+ die usage if @_;
+ $Do_Cache = 1;
+}
+
+$_Usage{disablecache} = <<'USAGE';
+usage: disablecache();
+USAGE
+
+sub disablecache {
+ die usage if @_;
+ $Do_Cache = 0;
+}
-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 new { my @t = (mytime, times, @_ == 2 ? $_[1] : 0);
+ print STDERR "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 iters { $_[0]->[5] ; }
+
+# return the sum of various times: which ones depending on $style
+
+sub elapsed {
+ my ($self, $style) = @_;
+ $style = "" unless defined $style;
+
+ return $self->cpu_c if $style eq 'nop';
+ return $self->cpu_p if $style eq 'noc';
+ return $self->cpu_a;
+}
+
+
+$_Usage{timediff} = <<'USAGE';
+usage: $result_diff = timediff($result1, $result2);
+USAGE
sub timediff {
my($a, $b) = @_;
+
+ die usage unless ref $a and ref $b;
+
my @r;
- for ($i=0; $i < @$a; ++$i) {
+ for (my $i=0; $i < @$a; ++$i) {
push(@r, $a->[$i] - $b->[$i]);
}
+ #die "Bad timediff(): ($r[1] + $r[2]) <= 0 (@$a[1,2]|@$b[1,2])\n"
+ # if ($r[1] + $r[2]) < 0;
bless \@r;
}
+$_Usage{timesum} = <<'USAGE';
+usage: $sum = timesum($result1, $result2);
+USAGE
+
+sub timesum {
+ my($a, $b) = @_;
+
+ die usage unless ref $a and ref $b;
+
+ my @r;
+ for (my $i=0; $i < @$a; ++$i) {
+ push(@r, $a->[$i] + $b->[$i]);
+ }
+ bless \@r;
+}
+
+
+$_Usage{timestr} = <<'USAGE';
+usage: $formatted_result = timestr($result1);
+USAGE
+
sub timestr {
my($tr, $style, $f) = @_;
+
+ die usage unless ref $tr;
+
my @t = @$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 defined $f;
+ warn "bad time value (@t)" unless @t==6;
+ my($r, $pu, $ps, $cu, $cs, $n) = @t;
+ my($pt, $ct, $tt) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a);
+ $f = $Default_Format unless defined $f;
# format a time in the required style, other formats may be added here
- $style ||= $defaultstyle;
+ $style ||= $Default_Style;
+ return '' if $style eq 'none';
$style = ($ct>0) ? 'all' : 'noc' if $style eq 'auto';
my $s = "@t $style"; # default for unknown style
- $s=sprintf("%2d secs (%$f usr %$f sys + %$f cusr %$f csys = %$f cpu)",
- @t,$t) if $style eq 'all';
- $s=sprintf("%2d secs (%$f usr %$f sys = %$f cpu)",
+ my $w = $hirestime ? "%2g" : "%2d";
+ $s = sprintf("$w wallclock secs (%$f usr %$f sys + %$f cusr %$f csys = %$f CPU)",
+ $r,$pu,$ps,$cu,$cs,$tt) if $style eq 'all';
+ $s = sprintf("$w wallclock secs (%$f usr + %$f sys = %$f CPU)",
$r,$pu,$ps,$pt) if $style eq 'noc';
- $s=sprintf("%2d secs (%$f cusr %$f csys = %$f cpu)",
+ $s = sprintf("$w wallclock secs (%$f cusr + %$f csys = %$f CPU)",
$r,$cu,$cs,$ct) if $style eq 'nop';
+ my $elapsed = $tr->elapsed($style);
+ $s .= sprintf(" @ %$f/s (n=$n)",$n/($elapsed)) if $n && $elapsed;
$s;
}
sub timedebug {
my($msg, $t) = @_;
- print STDERR "$msg",timestr($t),"\n" if $debug;
+ print STDERR "$msg",timestr($t),"\n" if $Debug;
}
# --- Functions implementing low-level support for timing loops
+$_Usage{runloop} = <<'USAGE';
+usage: runloop($number, [$string | $coderef])
+USAGE
+
sub runloop {
my($n, $c) = @_;
$n+=0; # force numeric now, so garbage won't creep into the eval
croak "negative loopcount $n" if $n<0;
- confess "Usage: runloop(number, [string | coderef])" unless defined $c;
+ confess usage unless defined $c;
my($t0, $t1, $td); # before, after, difference
# find package of caller so we can execute code there
last if $pack ne $curpack;
}
- my $subcode = (ref $c eq 'CODE')
- ? "sub { package $pack; my(\$_i)=$n; while (\$_i--){&\$c;} }"
- : "sub { package $pack; my(\$_i)=$n; while (\$_i--){$c;} }";
- my $subref = eval $subcode;
+ my ($subcode, $subref);
+ if (ref $c eq 'CODE') {
+ $subcode = "sub { for (1 .. $n) { local \$_; package $pack; &\$c; } }";
+ $subref = eval $subcode;
+ }
+ else {
+ $subcode = "sub { for (1 .. $n) { local \$_; package $pack; $c;} }";
+ $subref = _doeval($subcode);
+ }
croak "runloop unable to compile '$c': $@\ncode: $subcode\n" if $@;
- print STDERR "runloop $n '$subcode'\n" if $debug;
-
- $t0 = &new;
- &$subref;
- $t1 = &new;
+ print STDERR "runloop $n '$subcode'\n" if $Debug;
+
+ # Wait for the user timer to tick. This makes the error range more like
+ # -0.01, +0. If we don't wait, then it's more like -0.01, +0.01. This
+ # may not seem important, but it significantly reduces the chances of
+ # getting a too low initial $n in the initial, 'find the minimum' loop
+ # in &countit. This, in turn, can reduce the number of calls to
+ # &runloop a lot, and thus reduce additive errors.
+ #
+ # Note that its possible for the act of reading the system clock to
+ # burn lots of system CPU while we burn very little user clock in the
+ # busy loop, which can cause the loop to run for a very long wall time.
+ # So gradually ramp up the duration of the loop. See RT #122003
+ #
+ my $tbase = Benchmark->new(0)->[1];
+ my $limit = 1;
+ while ( ( $t0 = Benchmark->new(0) )->[1] == $tbase ) {
+ for (my $i=0; $i < $limit; $i++) { my $x = $i / 1.5 } # burn user CPU
+ $limit *= 1.1;
+ }
+ $subref->();
+ $t1 = Benchmark->new($n);
$td = &timediff($t1, $t0);
-
timedebug("runloop:",$td);
$td;
}
+$_Usage{timeit} = <<'USAGE';
+usage: $result = timeit($count, 'code' ); or
+ $result = timeit($count, sub { code } );
+USAGE
sub timeit {
my($n, $code) = @_;
my($wn, $wc, $wd);
- printf STDERR "timeit $n $code\n" if $debug;
+ die usage unless defined $code and
+ (!ref $code or ref $code eq 'CODE');
- if ($cache && exists $cache{$n}) {
- $wn = $cache{$n};
+ printf STDERR "timeit $n $code\n" if $Debug;
+ my $cache_key = $n . ( ref( $code ) ? 'c' : 's' );
+ if ($Do_Cache && exists $Cache{$cache_key} ) {
+ $wn = $Cache{$cache_key};
} else {
- $wn = &runloop($n, '');
- $cache{$n} = $wn;
+ $wn = &runloop($n, ref( $code ) ? sub { } : '' );
+ # Can't let our baseline have any iterations, or they get subtracted
+ # out of the result.
+ $wn->[5] = 0;
+ $Cache{$cache_key} = $wn;
}
$wc = &runloop($n, $code);
$wd = timediff($wc, $wn);
-
timedebug("timeit: ",$wc);
timedebug(" - ",$wn);
timedebug(" = ",$wd);
$wd;
}
+
+my $default_for = 3;
+my $min_for = 0.1;
+
+
+$_Usage{countit} = <<'USAGE';
+usage: $result = countit($time, 'code' ); or
+ $result = countit($time, sub { code } );
+USAGE
+
+sub countit {
+ my ( $tmax, $code ) = @_;
+
+ die usage unless @_;
+
+ if ( not defined $tmax or $tmax == 0 ) {
+ $tmax = $default_for;
+ } elsif ( $tmax < 0 ) {
+ $tmax = -$tmax;
+ }
+
+ die "countit($tmax, ...): timelimit cannot be less than $min_for.\n"
+ if $tmax < $min_for;
+
+ my ($n, $tc);
+
+ # First find the minimum $n that gives a significant timing.
+ my $zeros=0;
+ for ($n = 1; ; $n *= 2 ) {
+ my $t0 = Benchmark->new(0);
+ my $td = timeit($n, $code);
+ my $t1 = Benchmark->new(0);
+ $tc = $td->[1] + $td->[2];
+ if ( $tc <= 0 and $n > 1024 ) {
+ my $d = timediff($t1, $t0);
+ # note that $d is the total CPU time taken to call timeit(),
+ # while $tc is the difference in CPU secs between the empty run
+ # and the code run. If the code is trivial, its possible
+ # for $d to get large while $tc is still zero (or slightly
+ # negative). Bail out once timeit() starts taking more than a
+ # few seconds without noticeable difference.
+ if ($d->[1] + $d->[2] > 8
+ || ++$zeros > 16)
+ {
+ die "Timing is consistently zero in estimation loop, cannot benchmark. N=$n\n";
+ }
+ } else {
+ $zeros = 0;
+ }
+ last if $tc > 0.1;
+ }
+
+ my $nmin = $n;
+
+ # Get $n high enough that we can guess the final $n with some accuracy.
+ my $tpra = 0.1 * $tmax; # Target/time practice.
+ while ( $tc < $tpra ) {
+ # The 5% fudge is to keep us from iterating again all
+ # that often (this speeds overall responsiveness when $tmax is big
+ # and we guess a little low). This does not noticeably affect
+ # accuracy since we're not counting these times.
+ $n = int( $tpra * 1.05 * $n / $tc ); # Linear approximation.
+ my $td = timeit($n, $code);
+ 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
+ # the max.
+ my $ntot = 0;
+ my $rtot = 0;
+ my $utot = 0.0;
+ my $stot = 0.0;
+ my $cutot = 0.0;
+ my $cstot = 0.0;
+ my $ttot = 0.0;
+
+ # The 5% fudge is because $n is often a few % low even for routines
+ # with stable times and avoiding extra timeit()s is nice for
+ # accuracy's sake.
+ $n = int( $n * ( 1.05 * $tmax / $tc ) );
+ $zeros=0;
+ while () {
+ my $td = timeit($n, $code);
+ $ntot += $n;
+ $rtot += $td->[0];
+ $utot += $td->[1];
+ $stot += $td->[2];
+ $cutot += $td->[3];
+ $cstot += $td->[4];
+ $ttot = $utot + $stot;
+ last if $ttot >= $tmax;
+ if ( $ttot <= 0 ) {
+ ++$zeros > 16
+ and die "Timing is consistently zero, cannot benchmark. N=$n\n";
+ } else {
+ $zeros = 0;
+ }
+ $ttot = 0.01 if $ttot < 0.01;
+ my $r = $tmax / $ttot - 1; # Linear approximation.
+ $n = int( $r * $ntot );
+ $n = $nmin if $n < $nmin;
+ }
+
+ return bless [ $rtot, $utot, $stot, $cutot, $cstot, $ntot ];
+}
+
# --- Functions implementing high-level time-then-print utilities
+sub n_to_for {
+ my $n = shift;
+ return $n == 0 ? $default_for : $n < 0 ? -$n : undef;
+}
+
+$_Usage{timethis} = <<'USAGE';
+usage: $result = timethis($time, 'code' ); or
+ $result = timethis($time, sub { code } );
+USAGE
+
sub timethis{
my($n, $code, $title, $style) = @_;
- my $t = timeit($n, $code);
+ my($t, $forn);
+
+ die usage unless defined $code and
+ (!ref $code or ref $code eq 'CODE');
+
+ if ( $n > 0 ) {
+ croak "non-integer loopcount $n, stopped" if int($n)<$n;
+ $t = timeit($n, $code);
+ $title = "timethis $n" unless defined $title;
+ } else {
+ my $fort = n_to_for( $n );
+ $t = countit( $fort, $code );
+ $title = "timethis for $fort" unless defined $title;
+ $forn = $t->[-1];
+ }
local $| = 1;
- $title = "timethis $n" unless defined $title;
$style = "" unless defined $style;
- printf("%10s: ", $title);
- print timestr($t, $style),"\n";
+ printf("%10s: ", $title) unless $style eq 'none';
+ print timestr($t, $style, $Default_Format),"\n" unless $style eq 'none';
+
+ $n = $forn if defined $forn;
+
+ if ($t->elapsed($style) < 0) {
+ # due to clock granularity and variable CPU speed and load,
+ # on quick code with a small number of loops, it's possible for
+ # the empty loop to appear to take longer than the real loop
+ # (e.g. 1 tick versus 0 ticks). This leads to a negative elapsed
+ # time. In this case, floor it at zero, to stop bizarre results.
+ print " (warning: too few iterations for a reliable count)\n";
+ $t->[$_] = 0 for 1..4;
+ }
# 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
+ if $n < $Min_Count
|| ($t->real < 1 && $n < 1000)
- || $t->cpu_a < $min_cpu;
+ || $t->cpu_a < $Min_CPU;
$t;
}
+
+$_Usage{timethese} = <<'USAGE';
+usage: timethese($count, { Name1 => 'code1', ... }); or
+ timethese($count, { Name1 => sub { code1 }, ... });
+USAGE
+
sub timethese{
my($n, $alt, $style) = @_;
- die "usage: timethese(count, { 'Name1'=>'code1', ... }\n"
- unless ref $alt eq HASH;
+ die usage unless ref $alt eq 'HASH';
+
my @names = sort keys %$alt;
$style = "" unless defined $style;
- print "Benchmark: timing $n iterations of ",join(', ',@names),"...\n";
+ print "Benchmark: " unless $style eq 'none';
+ if ( $n > 0 ) {
+ croak "non-integer loopcount $n, stopped" if int($n)<$n;
+ print "timing $n iterations of" unless $style eq 'none';
+ } else {
+ print "running" unless $style eq 'none';
+ }
+ print " ", join(', ',@names) unless $style eq 'none';
+ unless ( $n > 0 ) {
+ my $for = n_to_for( $n );
+ print ", each" if $n > 1 && $style ne 'none';
+ print " for at least $for CPU seconds" unless $style eq 'none';
+ }
+ print "...\n" unless $style eq 'none';
# we could save the results in an array and produce a summary here
# sum, min, max, avg etc etc
- map timethis($n, $alt->{$_}, $_, $style), @names;
+ my %results;
+ foreach my $name (@names) {
+ $results{$name} = timethis ($n, $alt -> {$name}, $name, $style);
+ }
+
+ return \%results;
}
+
+$_Usage{cmpthese} = <<'USAGE';
+usage: cmpthese($count, { Name1 => 'code1', ... }); or
+ cmpthese($count, { Name1 => sub { code1 }, ... }); or
+ cmpthese($result, $style);
+USAGE
+
+sub cmpthese{
+ my ($results, $style);
+
+ # $count can be a blessed object.
+ if ( ref $_[0] eq 'HASH' ) {
+ ($results, $style) = @_;
+ }
+ else {
+ my($count, $code) = @_[0,1];
+ $style = $_[2] if defined $_[2];
+
+ die usage unless ref $code eq 'HASH';
+
+ $results = timethese($count, $code, ($style || "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;
+
+ for (@vals) {
+ # recreate the pre-flattened Benchmark object
+ my $tmp_bm = bless [ @{$_}[1..$#$_] ];
+ my $elapsed = $tmp_bm->elapsed($style);
+ # The epsilon fudge here is to prevent div by 0. Since clock
+ # resolutions are much larger, it's below the noise floor.
+ my $rate = $_->[6]/(($elapsed)+0.000000000000001);
+ $_->[7] = $rate;
+ }
+
+ # Sort by rate
+ @vals = sort { $a->[7] <=> $b->[7] } @vals;
+
+ # If more than half of the rates are greater than one...
+ my $display_as_rate = @vals ? ($vals[$#vals>>1]->[7] > 1) : 0;
+
+ my @rows;
+ my @col_widths;
+
+ my @top_row = (
+ '',
+ $display_as_rate ? 'Rate' : 's/iter',
+ map { $_->[0] } @vals
+ );
+
+ push @rows, \@top_row;
+ @col_widths = map { length( $_ ) } @top_row;
+
+ # Build the data rows
+ # We leave the last column in even though it never has any data. Perhaps
+ # it should go away. Also, perhaps a style for a single column of
+ # percentages might be nice.
+ for my $row_val ( @vals ) {
+ my @row;
+
+ # Column 0 = test name
+ push @row, $row_val->[0];
+ $col_widths[0] = length( $row_val->[0] )
+ if length( $row_val->[0] ) > $col_widths[0];
+
+ # Column 1 = performance
+ my $row_rate = $row_val->[7];
+
+ # We assume that we'll never get a 0 rate.
+ my $rate = $display_as_rate ? $row_rate : 1 / $row_rate;
+
+ # Only give a few decimal places before switching to sci. notation,
+ # since the results aren't usually that accurate anyway.
+ my $format =
+ $rate >= 100 ?
+ "%0.0f" :
+ $rate >= 10 ?
+ "%0.1f" :
+ $rate >= 1 ?
+ "%0.2f" :
+ $rate >= 0.1 ?
+ "%0.3f" :
+ "%0.2e";
+
+ $format .= "/s"
+ if $display_as_rate;
+
+ my $formatted_rate = sprintf( $format, $rate );
+ push @row, $formatted_rate;
+ $col_widths[1] = length( $formatted_rate )
+ if length( $formatted_rate ) > $col_widths[1];
+
+ # Columns 2..N = performance ratios
+ my $skip_rest = 0;
+ for ( my $col_num = 0 ; $col_num < @vals ; ++$col_num ) {
+ my $col_val = $vals[$col_num];
+ my $out;
+ if ( $skip_rest ) {
+ $out = '';
+ }
+ elsif ( $col_val->[0] eq $row_val->[0] ) {
+ $out = "--";
+ # $skip_rest = 1;
+ }
+ else {
+ my $col_rate = $col_val->[7];
+ $out = sprintf( "%.0f%%", 100*$row_rate/$col_rate - 100 );
+ }
+ push @row, $out;
+ $col_widths[$col_num+2] = length( $out )
+ if length( $out ) > $col_widths[$col_num+2];
+
+ # A little weirdness to set the first column width properly
+ $col_widths[$col_num+2] = length( $col_val->[0] )
+ if length( $col_val->[0] ) > $col_widths[$col_num+2];
+ }
+ 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 = @col_widths - 1 ;
+ for ( @col_widths ) { $total += $_ }
+
+ STRETCHER:
+ while ( $total < 80 ) {
+ my $min_width = ${$sorted_width_refs[0]};
+ last
+ if $min_width == $max_width;
+ for ( @sorted_width_refs ) {
+ last
+ if $$_ > $min_width;
+ ++$$_;
+ ++$total;
+ last STRETCHER
+ if $total >= 80;
+ }
+ }
+
+ # Dump the output
+ my $format = join( ' ', map { "%${_}s" } @col_widths ) . "\n";
+ substr( $format, 1, 0 ) = '-';
+ for ( @rows ) {
+ printf $format, @$_;
+ }
+
+ return \@rows ;
+}
+
+
1;
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