Commit | Line | Data |
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a0d0e21e LW |
1 | package Benchmark; |
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 ($count, "code"); | |
16 | ||
523cc92b | 17 | # Use Perl code in strings... |
f06db76b AD |
18 | timethese($count, { |
19 | 'Name1' => '...code1...', | |
20 | 'Name2' => '...code2...', | |
21 | }); | |
22 | ||
523cc92b CS |
23 | # ... or use subroutine references. |
24 | timethese($count, { | |
25 | 'Name1' => sub { ...code1... }, | |
26 | 'Name2' => sub { ...code2... }, | |
27 | }); | |
28 | ||
f06db76b AD |
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 AD |
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 AD |
59 | |
60 | =back | |
61 | ||
62 | =head2 Standard Exports | |
63 | ||
523cc92b | 64 | The following routines will be exported into your namespace |
f06db76b AD |
65 | if you use the Benchmark module: |
66 | ||
67 | =over 10 | |
68 | ||
69 | =item timeit(COUNT, CODE) | |
70 | ||
523cc92b CS |
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 | ||
85 | =item timethese ( COUNT, CODEHASHREF, [ STYLE ] ) | |
f06db76b | 86 | |
523cc92b CS |
87 | The CODEHASHREF is a reference to a hash containing names as keys |
88 | and either a string to eval or a code reference for each value. | |
89 | For each (KEY, VALUE) pair in the CODEHASHREF, this routine will | |
90 | call | |
f06db76b | 91 | |
523cc92b | 92 | timethis(COUNT, VALUE, KEY, STYLE) |
f06db76b | 93 | |
523cc92b | 94 | =item timediff ( T1, T2 ) |
f06db76b | 95 | |
523cc92b CS |
96 | Returns the difference between two Benchmark times as a Benchmark |
97 | object suitable for passing to timestr(). | |
f06db76b | 98 | |
523cc92b | 99 | =item timestr ( TIMEDIFF, [ STYLE, [ FORMAT ]] ) |
f06db76b | 100 | |
523cc92b CS |
101 | Returns a string that formats the times in the TIMEDIFF object in |
102 | the requested STYLE. TIMEDIFF is expected to be a Benchmark object | |
103 | similar to that returned by timediff(). | |
104 | ||
105 | STYLE can be any of 'all', 'noc', 'nop' or 'auto'. 'all' shows each | |
106 | of the 5 times available ('wallclock' time, user time, system time, | |
107 | user time of children, and system time of children). 'noc' shows all | |
108 | except the two children times. 'nop' shows only wallclock and the | |
109 | two children times. 'auto' (the default) will act as 'all' unless | |
110 | the children times are both zero, in which case it acts as 'noc'. | |
111 | ||
112 | FORMAT is the L<printf(3)>-style format specifier (without the | |
113 | leading '%') to use to print the times. It defaults to '5.2f'. | |
f06db76b AD |
114 | |
115 | =back | |
116 | ||
117 | =head2 Optional Exports | |
118 | ||
119 | The following routines will be exported into your namespace | |
120 | if you specifically ask that they be imported: | |
121 | ||
122 | =over 10 | |
123 | ||
523cc92b CS |
124 | =item clearcache ( COUNT ) |
125 | ||
126 | Clear the cached time for COUNT rounds of the null loop. | |
127 | ||
128 | =item clearallcache ( ) | |
f06db76b | 129 | |
523cc92b | 130 | Clear all cached times. |
f06db76b | 131 | |
523cc92b | 132 | =item disablecache ( ) |
f06db76b | 133 | |
523cc92b CS |
134 | Disable caching of timings for the null loop. This will force Benchmark |
135 | to recalculate these timings for each new piece of code timed. | |
136 | ||
137 | =item enablecache ( ) | |
138 | ||
139 | Enable caching of timings for the null loop. The time taken for COUNT | |
140 | rounds of the null loop will be calculated only once for each | |
141 | different COUNT used. | |
f06db76b AD |
142 | |
143 | =back | |
144 | ||
145 | =head1 NOTES | |
146 | ||
147 | The data is stored as a list of values from the time and times | |
523cc92b | 148 | functions: |
f06db76b AD |
149 | |
150 | ($real, $user, $system, $children_user, $children_system) | |
151 | ||
152 | in seconds for the whole loop (not divided by the number of rounds). | |
153 | ||
154 | The timing is done using time(3) and times(3). | |
155 | ||
156 | Code is executed in the caller's package. | |
157 | ||
f06db76b AD |
158 | The time of the null loop (a loop with the same |
159 | number of rounds but empty loop body) is subtracted | |
160 | from the time of the real loop. | |
161 | ||
162 | The null loop times are cached, the key being the | |
163 | number of rounds. The caching can be controlled using | |
164 | calls like these: | |
165 | ||
523cc92b | 166 | clearcache($key); |
f06db76b AD |
167 | clearallcache(); |
168 | ||
523cc92b | 169 | disablecache(); |
f06db76b AD |
170 | enablecache(); |
171 | ||
172 | =head1 INHERITANCE | |
173 | ||
174 | Benchmark inherits from no other class, except of course | |
175 | for Exporter. | |
176 | ||
177 | =head1 CAVEATS | |
178 | ||
80eab818 CS |
179 | Comparing eval'd strings with code references will give you |
180 | inaccurate results: a code reference will show a slower | |
181 | execution time than the equivalent eval'd string. | |
182 | ||
f06db76b AD |
183 | The real time timing is done using time(2) and |
184 | the granularity is therefore only one second. | |
185 | ||
186 | Short tests may produce negative figures because perl | |
523cc92b CS |
187 | can appear to take longer to execute the empty loop |
188 | than a short test; try: | |
f06db76b AD |
189 | |
190 | timethis(100,'1'); | |
191 | ||
192 | The system time of the null loop might be slightly | |
193 | more than the system time of the loop with the actual | |
a24a9dfe | 194 | code and therefore the difference might end up being E<lt> 0. |
f06db76b | 195 | |
f06db76b AD |
196 | =head1 AUTHORS |
197 | ||
5aabfad6 | 198 | Jarkko Hietaniemi <F<jhi@iki.fi>>, Tim Bunce <F<Tim.Bunce@ig.co.uk>> |
f06db76b AD |
199 | |
200 | =head1 MODIFICATION HISTORY | |
201 | ||
202 | September 8th, 1994; by Tim Bunce. | |
203 | ||
523cc92b CS |
204 | March 28th, 1997; by Hugo van der Sanden: added support for code |
205 | references and the already documented 'debug' method; revamped | |
206 | documentation. | |
f06db76b | 207 | |
523cc92b | 208 | =cut |
a0d0e21e | 209 | |
4aa0a1f7 | 210 | use Carp; |
a0d0e21e LW |
211 | use Exporter; |
212 | @ISA=(Exporter); | |
213 | @EXPORT=qw(timeit timethis timethese timediff timestr); | |
214 | @EXPORT_OK=qw(clearcache clearallcache disablecache enablecache); | |
215 | ||
216 | &init; | |
217 | ||
218 | sub init { | |
219 | $debug = 0; | |
220 | $min_count = 4; | |
221 | $min_cpu = 0.4; | |
222 | $defaultfmt = '5.2f'; | |
223 | $defaultstyle = 'auto'; | |
224 | # The cache can cause a slight loss of sys time accuracy. If a | |
225 | # user does many tests (>10) with *very* large counts (>10000) | |
226 | # or works on a very slow machine the cache may be useful. | |
227 | &disablecache; | |
228 | &clearallcache; | |
229 | } | |
230 | ||
523cc92b CS |
231 | sub debug { $debug = ($_[1] != 0); } |
232 | ||
a0d0e21e LW |
233 | sub clearcache { delete $cache{$_[0]}; } |
234 | sub clearallcache { %cache = (); } | |
235 | sub enablecache { $cache = 1; } | |
236 | sub disablecache { $cache = 0; } | |
237 | ||
a0d0e21e LW |
238 | # --- Functions to process the 'time' data type |
239 | ||
523cc92b | 240 | sub new { my @t = (time, times); print "new=@t\n" if $debug; bless \@t; } |
a0d0e21e LW |
241 | |
242 | sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps ; } | |
243 | sub cpu_c { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $cu+$cs ; } | |
244 | sub cpu_a { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps+$cu+$cs ; } | |
245 | sub real { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $r ; } | |
246 | ||
523cc92b | 247 | sub timediff { |
a0d0e21e | 248 | my($a, $b) = @_; |
523cc92b CS |
249 | my @r; |
250 | for ($i=0; $i < @$a; ++$i) { | |
a0d0e21e LW |
251 | push(@r, $a->[$i] - $b->[$i]); |
252 | } | |
253 | bless \@r; | |
254 | } | |
255 | ||
523cc92b | 256 | sub timestr { |
a0d0e21e | 257 | my($tr, $style, $f) = @_; |
523cc92b | 258 | my @t = @$tr; |
a0d0e21e LW |
259 | warn "bad time value" unless @t==5; |
260 | my($r, $pu, $ps, $cu, $cs) = @t; | |
261 | my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a); | |
523cc92b | 262 | $f = $defaultfmt unless defined $f; |
a0d0e21e | 263 | # format a time in the required style, other formats may be added here |
80eab818 | 264 | $style ||= $defaultstyle; |
523cc92b CS |
265 | $style = ($ct>0) ? 'all' : 'noc' if $style eq 'auto'; |
266 | my $s = "@t $style"; # default for unknown style | |
a0d0e21e | 267 | $s=sprintf("%2d secs (%$f usr %$f sys + %$f cusr %$f csys = %$f cpu)", |
523cc92b | 268 | @t,$t) if $style eq 'all'; |
a0d0e21e | 269 | $s=sprintf("%2d secs (%$f usr %$f sys = %$f cpu)", |
523cc92b | 270 | $r,$pu,$ps,$pt) if $style eq 'noc'; |
a0d0e21e | 271 | $s=sprintf("%2d secs (%$f cusr %$f csys = %$f cpu)", |
523cc92b | 272 | $r,$cu,$cs,$ct) if $style eq 'nop'; |
a0d0e21e LW |
273 | $s; |
274 | } | |
523cc92b CS |
275 | |
276 | sub timedebug { | |
a0d0e21e | 277 | my($msg, $t) = @_; |
523cc92b | 278 | print STDERR "$msg",timestr($t),"\n" if $debug; |
a0d0e21e LW |
279 | } |
280 | ||
a0d0e21e LW |
281 | # --- Functions implementing low-level support for timing loops |
282 | ||
283 | sub runloop { | |
284 | my($n, $c) = @_; | |
4aa0a1f7 AD |
285 | |
286 | $n+=0; # force numeric now, so garbage won't creep into the eval | |
523cc92b CS |
287 | croak "negative loopcount $n" if $n<0; |
288 | confess "Usage: runloop(number, [string | coderef])" unless defined $c; | |
a0d0e21e LW |
289 | my($t0, $t1, $td); # before, after, difference |
290 | ||
291 | # find package of caller so we can execute code there | |
523cc92b CS |
292 | my($curpack) = caller(0); |
293 | my($i, $pack)= 0; | |
a0d0e21e LW |
294 | while (($pack) = caller(++$i)) { |
295 | last if $pack ne $curpack; | |
296 | } | |
297 | ||
0d72c55d HS |
298 | my $subcode = (ref $c eq 'CODE') |
299 | ? "sub { package $pack; my(\$_i)=$n; while (\$_i--){&\$c;} }" | |
300 | : "sub { package $pack; my(\$_i)=$n; while (\$_i--){$c;} }"; | |
a0d0e21e | 301 | my $subref = eval $subcode; |
4aa0a1f7 | 302 | croak "runloop unable to compile '$c': $@\ncode: $subcode\n" if $@; |
523cc92b | 303 | print STDERR "runloop $n '$subcode'\n" if $debug; |
a0d0e21e LW |
304 | |
305 | $t0 = &new; | |
306 | &$subref; | |
307 | $t1 = &new; | |
308 | $td = &timediff($t1, $t0); | |
309 | ||
310 | timedebug("runloop:",$td); | |
311 | $td; | |
312 | } | |
313 | ||
314 | ||
315 | sub timeit { | |
316 | my($n, $code) = @_; | |
317 | my($wn, $wc, $wd); | |
318 | ||
319 | printf STDERR "timeit $n $code\n" if $debug; | |
320 | ||
523cc92b | 321 | if ($cache && exists $cache{$n}) { |
a0d0e21e | 322 | $wn = $cache{$n}; |
523cc92b | 323 | } else { |
a0d0e21e LW |
324 | $wn = &runloop($n, ''); |
325 | $cache{$n} = $wn; | |
326 | } | |
327 | ||
328 | $wc = &runloop($n, $code); | |
329 | ||
330 | $wd = timediff($wc, $wn); | |
331 | ||
332 | timedebug("timeit: ",$wc); | |
333 | timedebug(" - ",$wn); | |
334 | timedebug(" = ",$wd); | |
335 | ||
336 | $wd; | |
337 | } | |
338 | ||
a0d0e21e LW |
339 | # --- Functions implementing high-level time-then-print utilities |
340 | ||
341 | sub timethis{ | |
342 | my($n, $code, $title, $style) = @_; | |
523cc92b CS |
343 | my $t = timeit($n, $code); |
344 | local $| = 1; | |
345 | $title = "timethis $n" unless defined $title; | |
346 | $style = "" unless defined $style; | |
a0d0e21e LW |
347 | printf("%10s: ", $title); |
348 | print timestr($t, $style),"\n"; | |
523cc92b | 349 | |
a0d0e21e LW |
350 | # A conservative warning to spot very silly tests. |
351 | # Don't assume that your benchmark is ok simply because | |
352 | # you don't get this warning! | |
353 | print " (warning: too few iterations for a reliable count)\n" | |
523cc92b | 354 | if $n < $min_count |
a0d0e21e | 355 | || ($t->real < 1 && $n < 1000) |
523cc92b | 356 | || $t->cpu_a < $min_cpu; |
a0d0e21e LW |
357 | $t; |
358 | } | |
359 | ||
a0d0e21e LW |
360 | sub timethese{ |
361 | my($n, $alt, $style) = @_; | |
362 | die "usage: timethese(count, { 'Name1'=>'code1', ... }\n" | |
363 | unless ref $alt eq HASH; | |
523cc92b CS |
364 | my @names = sort keys %$alt; |
365 | $style = "" unless defined $style; | |
a0d0e21e | 366 | print "Benchmark: timing $n iterations of ",join(', ',@names),"...\n"; |
523cc92b CS |
367 | |
368 | # we could save the results in an array and produce a summary here | |
a0d0e21e | 369 | # sum, min, max, avg etc etc |
4dbb2df9 A |
370 | foreach my $name (@names) { |
371 | timethis ($n, $alt -> {$name}, $name, $style); | |
372 | } | |
a0d0e21e LW |
373 | } |
374 | ||
a0d0e21e | 375 | 1; |