Commit | Line | Data |
a0d0e21e |
1 | package Benchmark; |
2 | |
f06db76b |
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 ($count, "code"); |
16 | |
523cc92b |
17 | # Use Perl code in strings... |
f06db76b |
18 | timethese($count, { |
19 | 'Name1' => '...code1...', |
20 | 'Name2' => '...code2...', |
21 | }); |
22 | |
523cc92b |
23 | # ... or use subroutine references. |
24 | timethese($count, { |
25 | 'Name1' => sub { ...code1... }, |
26 | 'Name2' => sub { ...code2... }, |
27 | }); |
28 | |
f06db76b |
29 | $t = timeit($count, '...other code...') |
30 | print "$count loops of other code took:",timestr($t),"\n"; |
31 | |
32 | =head1 DESCRIPTION |
33 | |
34 | The Benchmark module encapsulates a number of routines to help you |
35 | figure out how long it takes to execute some code. |
36 | |
37 | =head2 Methods |
38 | |
39 | =over 10 |
40 | |
41 | =item new |
42 | |
43 | Returns the current time. Example: |
44 | |
45 | use Benchmark; |
46 | $t0 = new Benchmark; |
47 | # ... your code here ... |
48 | $t1 = new Benchmark; |
49 | $td = timediff($t1, $t0); |
a24a9dfe |
50 | print "the code took:",timestr($td),"\n"; |
f06db76b |
51 | |
52 | =item debug |
53 | |
54 | Enables or disable debugging by setting the C<$Benchmark::Debug> flag: |
55 | |
523cc92b |
56 | debug Benchmark 1; |
f06db76b |
57 | $t = timeit(10, ' 5 ** $Global '); |
523cc92b |
58 | debug Benchmark 0; |
f06db76b |
59 | |
60 | =back |
61 | |
62 | =head2 Standard Exports |
63 | |
523cc92b |
64 | The following routines will be exported into your namespace |
f06db76b |
65 | if you use the Benchmark module: |
66 | |
67 | =over 10 |
68 | |
69 | =item timeit(COUNT, CODE) |
70 | |
523cc92b |
71 | Arguments: COUNT is the number of times to run the loop, and CODE is |
72 | the code to run. CODE may be either a code reference or a string to |
73 | be eval'd; either way it will be run in the caller's package. |
74 | |
75 | Returns: a Benchmark object. |
76 | |
77 | =item timethis ( COUNT, CODE, [ TITLE, [ STYLE ]] ) |
78 | |
79 | Time COUNT iterations of CODE. CODE may be a string to eval or a |
80 | code reference; either way the CODE will run in the caller's package. |
81 | Results will be printed to STDOUT as TITLE followed by the times. |
82 | TITLE defaults to "timethis COUNT" if none is provided. STYLE |
83 | determines the format of the output, as described for timestr() below. |
84 | |
6ee623d5 |
85 | The COUNT can be zero or negative: this means the I<minimum number of |
86 | CPU seconds> to run. A zero signifies the default of 3 seconds. For |
87 | example to run at least for 10 seconds: |
88 | |
89 | timethis(-10, $code) |
90 | |
91 | or to run two pieces of code tests for at least 3 seconds: |
92 | |
93 | timethese(0, { test1 => '...', test2 => '...'}) |
94 | |
95 | CPU seconds is, in UNIX terms, the user time plus the system time of |
96 | the process itself, as opposed to the real (wallclock) time and the |
97 | time spent by the child processes. Less than 0.1 seconds is not |
98 | accepted (-0.01 as the count, for example, will cause a fatal runtime |
99 | exception). |
100 | |
101 | Note that the CPU seconds is the B<minimum> time: CPU scheduling and |
102 | other operating system factors may complicate the attempt so that a |
103 | little bit more time is spent. The benchmark output will, however, |
104 | also tell the number of C<$code> runs/second, which should be a more |
105 | interesting number than the actually spent seconds. |
106 | |
107 | Returns a Benchmark object. |
108 | |
523cc92b |
109 | =item timethese ( COUNT, CODEHASHREF, [ STYLE ] ) |
f06db76b |
110 | |
523cc92b |
111 | The CODEHASHREF is a reference to a hash containing names as keys |
112 | and either a string to eval or a code reference for each value. |
113 | For each (KEY, VALUE) pair in the CODEHASHREF, this routine will |
114 | call |
f06db76b |
115 | |
523cc92b |
116 | timethis(COUNT, VALUE, KEY, STYLE) |
f06db76b |
117 | |
1d2dff63 |
118 | The routines are called in string comparison order of KEY. |
119 | |
120 | The COUNT can be zero or negative, see timethis(). |
6ee623d5 |
121 | |
523cc92b |
122 | =item timediff ( T1, T2 ) |
f06db76b |
123 | |
523cc92b |
124 | Returns the difference between two Benchmark times as a Benchmark |
125 | object suitable for passing to timestr(). |
f06db76b |
126 | |
6ee623d5 |
127 | =item timestr ( TIMEDIFF, [ STYLE, [ FORMAT ] ] ) |
f06db76b |
128 | |
523cc92b |
129 | Returns a string that formats the times in the TIMEDIFF object in |
130 | the requested STYLE. TIMEDIFF is expected to be a Benchmark object |
131 | similar to that returned by timediff(). |
132 | |
133 | STYLE can be any of 'all', 'noc', 'nop' or 'auto'. 'all' shows each |
134 | of the 5 times available ('wallclock' time, user time, system time, |
135 | user time of children, and system time of children). 'noc' shows all |
136 | except the two children times. 'nop' shows only wallclock and the |
137 | two children times. 'auto' (the default) will act as 'all' unless |
138 | the children times are both zero, in which case it acts as 'noc'. |
139 | |
140 | FORMAT is the L<printf(3)>-style format specifier (without the |
141 | leading '%') to use to print the times. It defaults to '5.2f'. |
f06db76b |
142 | |
143 | =back |
144 | |
145 | =head2 Optional Exports |
146 | |
147 | The following routines will be exported into your namespace |
148 | if you specifically ask that they be imported: |
149 | |
150 | =over 10 |
151 | |
523cc92b |
152 | =item clearcache ( COUNT ) |
153 | |
154 | Clear the cached time for COUNT rounds of the null loop. |
155 | |
156 | =item clearallcache ( ) |
f06db76b |
157 | |
523cc92b |
158 | Clear all cached times. |
f06db76b |
159 | |
523cc92b |
160 | =item disablecache ( ) |
f06db76b |
161 | |
523cc92b |
162 | Disable caching of timings for the null loop. This will force Benchmark |
163 | to recalculate these timings for each new piece of code timed. |
164 | |
165 | =item enablecache ( ) |
166 | |
167 | Enable caching of timings for the null loop. The time taken for COUNT |
168 | rounds of the null loop will be calculated only once for each |
169 | different COUNT used. |
f06db76b |
170 | |
171 | =back |
172 | |
173 | =head1 NOTES |
174 | |
175 | The data is stored as a list of values from the time and times |
523cc92b |
176 | functions: |
f06db76b |
177 | |
178 | ($real, $user, $system, $children_user, $children_system) |
179 | |
180 | in seconds for the whole loop (not divided by the number of rounds). |
181 | |
182 | The timing is done using time(3) and times(3). |
183 | |
184 | Code is executed in the caller's package. |
185 | |
f06db76b |
186 | The time of the null loop (a loop with the same |
187 | number of rounds but empty loop body) is subtracted |
188 | from the time of the real loop. |
189 | |
190 | The null loop times are cached, the key being the |
191 | number of rounds. The caching can be controlled using |
192 | calls like these: |
193 | |
523cc92b |
194 | clearcache($key); |
f06db76b |
195 | clearallcache(); |
196 | |
523cc92b |
197 | disablecache(); |
f06db76b |
198 | enablecache(); |
199 | |
200 | =head1 INHERITANCE |
201 | |
202 | Benchmark inherits from no other class, except of course |
203 | for Exporter. |
204 | |
205 | =head1 CAVEATS |
206 | |
80eab818 |
207 | Comparing eval'd strings with code references will give you |
208 | inaccurate results: a code reference will show a slower |
209 | execution time than the equivalent eval'd string. |
210 | |
f06db76b |
211 | The real time timing is done using time(2) and |
212 | the granularity is therefore only one second. |
213 | |
214 | Short tests may produce negative figures because perl |
523cc92b |
215 | can appear to take longer to execute the empty loop |
216 | than a short test; try: |
f06db76b |
217 | |
218 | timethis(100,'1'); |
219 | |
220 | The system time of the null loop might be slightly |
221 | more than the system time of the loop with the actual |
a24a9dfe |
222 | code and therefore the difference might end up being E<lt> 0. |
f06db76b |
223 | |
f06db76b |
224 | =head1 AUTHORS |
225 | |
5aabfad6 |
226 | Jarkko Hietaniemi <F<jhi@iki.fi>>, Tim Bunce <F<Tim.Bunce@ig.co.uk>> |
f06db76b |
227 | |
228 | =head1 MODIFICATION HISTORY |
229 | |
230 | September 8th, 1994; by Tim Bunce. |
231 | |
523cc92b |
232 | March 28th, 1997; by Hugo van der Sanden: added support for code |
233 | references and the already documented 'debug' method; revamped |
234 | documentation. |
f06db76b |
235 | |
6ee623d5 |
236 | April 04-07th, 1997: by Jarkko Hietaniemi, added the run-for-some-time |
237 | functionality. |
238 | |
523cc92b |
239 | =cut |
a0d0e21e |
240 | |
4aa0a1f7 |
241 | use Carp; |
a0d0e21e |
242 | use Exporter; |
243 | @ISA=(Exporter); |
244 | @EXPORT=qw(timeit timethis timethese timediff timestr); |
245 | @EXPORT_OK=qw(clearcache clearallcache disablecache enablecache); |
246 | |
247 | &init; |
248 | |
249 | sub init { |
250 | $debug = 0; |
251 | $min_count = 4; |
252 | $min_cpu = 0.4; |
253 | $defaultfmt = '5.2f'; |
254 | $defaultstyle = 'auto'; |
255 | # The cache can cause a slight loss of sys time accuracy. If a |
256 | # user does many tests (>10) with *very* large counts (>10000) |
257 | # or works on a very slow machine the cache may be useful. |
258 | &disablecache; |
259 | &clearallcache; |
260 | } |
261 | |
523cc92b |
262 | sub debug { $debug = ($_[1] != 0); } |
263 | |
a0d0e21e |
264 | sub clearcache { delete $cache{$_[0]}; } |
265 | sub clearallcache { %cache = (); } |
266 | sub enablecache { $cache = 1; } |
267 | sub disablecache { $cache = 0; } |
268 | |
a0d0e21e |
269 | # --- Functions to process the 'time' data type |
270 | |
6ee623d5 |
271 | sub new { my @t = (time, times, @_ == 2 ? $_[1] : 0); |
272 | print "new=@t\n" if $debug; |
273 | bless \@t; } |
a0d0e21e |
274 | |
275 | sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps ; } |
276 | sub cpu_c { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $cu+$cs ; } |
277 | sub cpu_a { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps+$cu+$cs ; } |
278 | sub real { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $r ; } |
279 | |
523cc92b |
280 | sub timediff { |
a0d0e21e |
281 | my($a, $b) = @_; |
523cc92b |
282 | my @r; |
283 | for ($i=0; $i < @$a; ++$i) { |
a0d0e21e |
284 | push(@r, $a->[$i] - $b->[$i]); |
285 | } |
286 | bless \@r; |
287 | } |
288 | |
523cc92b |
289 | sub timestr { |
a0d0e21e |
290 | my($tr, $style, $f) = @_; |
523cc92b |
291 | my @t = @$tr; |
6ee623d5 |
292 | warn "bad time value (@t)" unless @t==6; |
293 | my($r, $pu, $ps, $cu, $cs, $n) = @t; |
a0d0e21e |
294 | my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a); |
523cc92b |
295 | $f = $defaultfmt unless defined $f; |
a0d0e21e |
296 | # format a time in the required style, other formats may be added here |
80eab818 |
297 | $style ||= $defaultstyle; |
523cc92b |
298 | $style = ($ct>0) ? 'all' : 'noc' if $style eq 'auto'; |
299 | my $s = "@t $style"; # default for unknown style |
7be077a2 |
300 | $s=sprintf("%2d wallclock secs (%$f usr %$f sys + %$f cusr %$f csys = %$f CPU)", |
523cc92b |
301 | @t,$t) if $style eq 'all'; |
7be077a2 |
302 | $s=sprintf("%2d wallclock secs (%$f usr + %$f sys = %$f CPU)", |
303 | $r,$pu,$ps,$pt) if $style eq 'noc'; |
304 | $s=sprintf("%2d wallclock secs (%$f cusr + %$f csys = %$f CPU)", |
305 | $r,$cu,$cs,$ct) if $style eq 'nop'; |
6ee623d5 |
306 | $s .= sprintf(" @ %$f/s (n=$n)", $n / ( $pu + $ps )) if $n; |
a0d0e21e |
307 | $s; |
308 | } |
523cc92b |
309 | |
310 | sub timedebug { |
a0d0e21e |
311 | my($msg, $t) = @_; |
523cc92b |
312 | print STDERR "$msg",timestr($t),"\n" if $debug; |
a0d0e21e |
313 | } |
314 | |
a0d0e21e |
315 | # --- Functions implementing low-level support for timing loops |
316 | |
317 | sub runloop { |
318 | my($n, $c) = @_; |
4aa0a1f7 |
319 | |
320 | $n+=0; # force numeric now, so garbage won't creep into the eval |
523cc92b |
321 | croak "negative loopcount $n" if $n<0; |
322 | confess "Usage: runloop(number, [string | coderef])" unless defined $c; |
a0d0e21e |
323 | my($t0, $t1, $td); # before, after, difference |
324 | |
325 | # find package of caller so we can execute code there |
523cc92b |
326 | my($curpack) = caller(0); |
327 | my($i, $pack)= 0; |
a0d0e21e |
328 | while (($pack) = caller(++$i)) { |
329 | last if $pack ne $curpack; |
330 | } |
331 | |
0d72c55d |
332 | my $subcode = (ref $c eq 'CODE') |
333 | ? "sub { package $pack; my(\$_i)=$n; while (\$_i--){&\$c;} }" |
334 | : "sub { package $pack; my(\$_i)=$n; while (\$_i--){$c;} }"; |
a0d0e21e |
335 | my $subref = eval $subcode; |
4aa0a1f7 |
336 | croak "runloop unable to compile '$c': $@\ncode: $subcode\n" if $@; |
523cc92b |
337 | print STDERR "runloop $n '$subcode'\n" if $debug; |
a0d0e21e |
338 | |
6ee623d5 |
339 | $t0 = Benchmark->new(0); |
a0d0e21e |
340 | &$subref; |
6ee623d5 |
341 | $t1 = Benchmark->new($n); |
a0d0e21e |
342 | $td = &timediff($t1, $t0); |
343 | |
344 | timedebug("runloop:",$td); |
345 | $td; |
346 | } |
347 | |
348 | |
349 | sub timeit { |
350 | my($n, $code) = @_; |
351 | my($wn, $wc, $wd); |
352 | |
353 | printf STDERR "timeit $n $code\n" if $debug; |
354 | |
523cc92b |
355 | if ($cache && exists $cache{$n}) { |
a0d0e21e |
356 | $wn = $cache{$n}; |
523cc92b |
357 | } else { |
a0d0e21e |
358 | $wn = &runloop($n, ''); |
359 | $cache{$n} = $wn; |
360 | } |
361 | |
362 | $wc = &runloop($n, $code); |
363 | |
364 | $wd = timediff($wc, $wn); |
365 | |
366 | timedebug("timeit: ",$wc); |
367 | timedebug(" - ",$wn); |
368 | timedebug(" = ",$wd); |
369 | |
370 | $wd; |
371 | } |
372 | |
6ee623d5 |
373 | |
374 | my $default_for = 3; |
375 | my $min_for = 0.1; |
376 | |
377 | sub runfor { |
378 | my ($code, $tmax) = @_; |
379 | |
380 | if ( not defined $tmax or $tmax == 0 ) { |
381 | $tmax = $default_for; |
382 | } elsif ( $tmax < 0 ) { |
383 | $tmax = -$tmax; |
384 | } |
385 | |
386 | die "runfor(..., $tmax): timelimit cannot be less than $min_for.\n" |
387 | if $tmax < $min_for; |
388 | |
389 | my ($n, $td, $tc, $ntot, $rtot, $utot, $stot, $cutot, $cstot ); |
390 | |
391 | # First find the minimum $n that gives a non-zero timing. |
392 | |
393 | my $nmin; |
394 | |
395 | for ($n = 1, $tc = 0; $tc <= 0; $n *= 2 ) { |
396 | $td = timeit($n, $code); |
397 | $tc = $td->[1] + $td->[2]; |
398 | } |
399 | |
400 | $nmin = $n; |
401 | |
402 | my $ttot = 0; |
403 | my $tpra = 0.05 * $tmax; # Target/time practice. |
404 | |
405 | # Double $n until we have think we have practiced enough. |
406 | for ( $n = 1; $ttot < $tpra; $n *= 2 ) { |
407 | $td = timeit($n, $code); |
408 | $tc = $td->cpu_p; |
409 | $ntot += $n; |
410 | $rtot += $td->[0]; |
411 | $utot += $td->[1]; |
412 | $stot += $td->[2]; |
413 | $ttot = $utot + $stot; |
414 | $cutot += $td->[3]; |
415 | $cstot += $td->[4]; |
416 | } |
417 | |
418 | my $r; |
419 | |
420 | # Then iterate towards the $tmax. |
421 | while ( $ttot < $tmax ) { |
422 | $r = $tmax / $ttot - 1; # Linear approximation. |
423 | $n = int( $r * $n ); |
424 | $n = $nmin if $n < $nmin; |
425 | $td = timeit($n, $code); |
426 | $ntot += $n; |
427 | $rtot += $td->[0]; |
428 | $utot += $td->[1]; |
429 | $stot += $td->[2]; |
430 | $ttot = $utot + $stot; |
431 | $cutot += $td->[3]; |
432 | $cstot += $td->[4]; |
433 | } |
434 | |
435 | return bless [ $rtot, $utot, $stot, $cutot, $cstot, $ntot ]; |
436 | } |
437 | |
a0d0e21e |
438 | # --- Functions implementing high-level time-then-print utilities |
439 | |
6ee623d5 |
440 | sub n_to_for { |
441 | my $n = shift; |
442 | return $n == 0 ? $default_for : $n < 0 ? -$n : undef; |
443 | } |
444 | |
a0d0e21e |
445 | sub timethis{ |
446 | my($n, $code, $title, $style) = @_; |
6ee623d5 |
447 | my($t, $for, $forn); |
448 | |
449 | if ( $n > 0 ) { |
450 | croak "non-integer loopcount $n, stopped" if int($n)<$n; |
451 | $t = timeit($n, $code); |
452 | $title = "timethis $n" unless defined $title; |
453 | } else { |
454 | $fort = n_to_for( $n ); |
455 | $t = runfor($code, $fort); |
456 | $title = "timethis for $fort" unless defined $title; |
457 | $forn = $t->[-1]; |
458 | } |
523cc92b |
459 | local $| = 1; |
523cc92b |
460 | $style = "" unless defined $style; |
a0d0e21e |
461 | printf("%10s: ", $title); |
6ee623d5 |
462 | print timestr($t, $style, $defaultfmt),"\n"; |
463 | |
464 | $n = $forn if defined $forn; |
523cc92b |
465 | |
a0d0e21e |
466 | # A conservative warning to spot very silly tests. |
467 | # Don't assume that your benchmark is ok simply because |
468 | # you don't get this warning! |
469 | print " (warning: too few iterations for a reliable count)\n" |
523cc92b |
470 | if $n < $min_count |
a0d0e21e |
471 | || ($t->real < 1 && $n < 1000) |
523cc92b |
472 | || $t->cpu_a < $min_cpu; |
a0d0e21e |
473 | $t; |
474 | } |
475 | |
a0d0e21e |
476 | sub timethese{ |
477 | my($n, $alt, $style) = @_; |
478 | die "usage: timethese(count, { 'Name1'=>'code1', ... }\n" |
479 | unless ref $alt eq HASH; |
523cc92b |
480 | my @names = sort keys %$alt; |
481 | $style = "" unless defined $style; |
6ee623d5 |
482 | print "Benchmark: "; |
483 | if ( $n > 0 ) { |
484 | croak "non-integer loopcount $n, stopped" if int($n)<$n; |
485 | print "timing $n iterations of"; |
486 | } else { |
487 | print "running"; |
488 | } |
489 | print " ", join(', ',@names); |
490 | unless ( $n > 0 ) { |
491 | my $for = n_to_for( $n ); |
492 | print ", each for at least $for CPU seconds"; |
493 | } |
494 | print "...\n"; |
523cc92b |
495 | |
496 | # we could save the results in an array and produce a summary here |
a0d0e21e |
497 | # sum, min, max, avg etc etc |
4dbb2df9 |
498 | foreach my $name (@names) { |
499 | timethis ($n, $alt -> {$name}, $name, $style); |
500 | } |
a0d0e21e |
501 | } |
502 | |
a0d0e21e |
503 | 1; |