Commit | Line | Data |
---|---|---|
920dae64 AT |
1 | .\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32 |
2 | .\" | |
3 | .\" Standard preamble: | |
4 | .\" ======================================================================== | |
5 | .de Sh \" Subsection heading | |
6 | .br | |
7 | .if t .Sp | |
8 | .ne 5 | |
9 | .PP | |
10 | \fB\\$1\fR | |
11 | .PP | |
12 | .. | |
13 | .de Sp \" Vertical space (when we can't use .PP) | |
14 | .if t .sp .5v | |
15 | .if n .sp | |
16 | .. | |
17 | .de Vb \" Begin verbatim text | |
18 | .ft CW | |
19 | .nf | |
20 | .ne \\$1 | |
21 | .. | |
22 | .de Ve \" End verbatim text | |
23 | .ft R | |
24 | .fi | |
25 | .. | |
26 | .\" Set up some character translations and predefined strings. \*(-- will | |
27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left | |
28 | .\" double quote, and \*(R" will give a right double quote. | will give a | |
29 | .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to | |
30 | .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' | |
31 | .\" expand to `' in nroff, nothing in troff, for use with C<>. | |
32 | .tr \(*W-|\(bv\*(Tr | |
33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' | |
34 | .ie n \{\ | |
35 | . ds -- \(*W- | |
36 | . ds PI pi | |
37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch | |
38 | . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch | |
39 | . ds L" "" | |
40 | . ds R" "" | |
41 | . ds C` "" | |
42 | . ds C' "" | |
43 | 'br\} | |
44 | .el\{\ | |
45 | . ds -- \|\(em\| | |
46 | . ds PI \(*p | |
47 | . ds L" `` | |
48 | . ds R" '' | |
49 | 'br\} | |
50 | .\" | |
51 | .\" If the F register is turned on, we'll generate index entries on stderr for | |
52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index | |
53 | .\" entries marked with X<> in POD. Of course, you'll have to process the | |
54 | .\" output yourself in some meaningful fashion. | |
55 | .if \nF \{\ | |
56 | . de IX | |
57 | . tm Index:\\$1\t\\n%\t"\\$2" | |
58 | .. | |
59 | . nr % 0 | |
60 | . rr F | |
61 | .\} | |
62 | .\" | |
63 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes | |
64 | .\" way too many mistakes in technical documents. | |
65 | .hy 0 | |
66 | .if n .na | |
67 | .\" | |
68 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). | |
69 | .\" Fear. Run. Save yourself. No user-serviceable parts. | |
70 | . \" fudge factors for nroff and troff | |
71 | .if n \{\ | |
72 | . ds #H 0 | |
73 | . ds #V .8m | |
74 | . ds #F .3m | |
75 | . ds #[ \f1 | |
76 | . ds #] \fP | |
77 | .\} | |
78 | .if t \{\ | |
79 | . ds #H ((1u-(\\\\n(.fu%2u))*.13m) | |
80 | . ds #V .6m | |
81 | . ds #F 0 | |
82 | . ds #[ \& | |
83 | . ds #] \& | |
84 | .\} | |
85 | . \" simple accents for nroff and troff | |
86 | .if n \{\ | |
87 | . ds ' \& | |
88 | . ds ` \& | |
89 | . ds ^ \& | |
90 | . ds , \& | |
91 | . ds ~ ~ | |
92 | . ds / | |
93 | .\} | |
94 | .if t \{\ | |
95 | . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" | |
96 | . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' | |
97 | . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' | |
98 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' | |
99 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' | |
100 | . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' | |
101 | .\} | |
102 | . \" troff and (daisy-wheel) nroff accents | |
103 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' | |
104 | .ds 8 \h'\*(#H'\(*b\h'-\*(#H' | |
105 | .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] | |
106 | .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' | |
107 | .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' | |
108 | .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] | |
109 | .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] | |
110 | .ds ae a\h'-(\w'a'u*4/10)'e | |
111 | .ds Ae A\h'-(\w'A'u*4/10)'E | |
112 | . \" corrections for vroff | |
113 | .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' | |
114 | .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' | |
115 | . \" for low resolution devices (crt and lpr) | |
116 | .if \n(.H>23 .if \n(.V>19 \ | |
117 | \{\ | |
118 | . ds : e | |
119 | . ds 8 ss | |
120 | . ds o a | |
121 | . ds d- d\h'-1'\(ga | |
122 | . ds D- D\h'-1'\(hy | |
123 | . ds th \o'bp' | |
124 | . ds Th \o'LP' | |
125 | . ds ae ae | |
126 | . ds Ae AE | |
127 | .\} | |
128 | .rm #[ #] #H #V #F C | |
129 | .\" ======================================================================== | |
130 | .\" | |
131 | .IX Title "Benchmark 3" | |
132 | .TH Benchmark 3 "2001-09-21" "perl v5.8.8" "Perl Programmers Reference Guide" | |
133 | .SH "NAME" | |
134 | Benchmark \- benchmark running times of Perl code | |
135 | .SH "SYNOPSIS" | |
136 | .IX Header "SYNOPSIS" | |
137 | .Vb 1 | |
138 | \& use Benchmark qw(:all) ; | |
139 | .Ve | |
140 | .PP | |
141 | .Vb 1 | |
142 | \& timethis ($count, "code"); | |
143 | .Ve | |
144 | .PP | |
145 | .Vb 5 | |
146 | \& # Use Perl code in strings... | |
147 | \& timethese($count, { | |
148 | \& 'Name1' => '...code1...', | |
149 | \& 'Name2' => '...code2...', | |
150 | \& }); | |
151 | .Ve | |
152 | .PP | |
153 | .Vb 5 | |
154 | \& # ... or use subroutine references. | |
155 | \& timethese($count, { | |
156 | \& 'Name1' => sub { ...code1... }, | |
157 | \& 'Name2' => sub { ...code2... }, | |
158 | \& }); | |
159 | .Ve | |
160 | .PP | |
161 | .Vb 5 | |
162 | \& # cmpthese can be used both ways as well | |
163 | \& cmpthese($count, { | |
164 | \& 'Name1' => '...code1...', | |
165 | \& 'Name2' => '...code2...', | |
166 | \& }); | |
167 | .Ve | |
168 | .PP | |
169 | .Vb 4 | |
170 | \& cmpthese($count, { | |
171 | \& 'Name1' => sub { ...code1... }, | |
172 | \& 'Name2' => sub { ...code2... }, | |
173 | \& }); | |
174 | .Ve | |
175 | .PP | |
176 | .Vb 9 | |
177 | \& # ...or in two stages | |
178 | \& $results = timethese($count, | |
179 | \& { | |
180 | \& 'Name1' => sub { ...code1... }, | |
181 | \& 'Name2' => sub { ...code2... }, | |
182 | \& }, | |
183 | \& 'none' | |
184 | \& ); | |
185 | \& cmpthese( $results ) ; | |
186 | .Ve | |
187 | .PP | |
188 | .Vb 2 | |
189 | \& $t = timeit($count, '...other code...') | |
190 | \& print "$count loops of other code took:",timestr($t),"\en"; | |
191 | .Ve | |
192 | .PP | |
193 | .Vb 3 | |
194 | \& $t = countit($time, '...other code...') | |
195 | \& $count = $t->iters ; | |
196 | \& print "$count loops of other code took:",timestr($t),"\en"; | |
197 | .Ve | |
198 | .PP | |
199 | .Vb 2 | |
200 | \& # enable hires wallclock timing if possible | |
201 | \& use Benchmark ':hireswallclock'; | |
202 | .Ve | |
203 | .SH "DESCRIPTION" | |
204 | .IX Header "DESCRIPTION" | |
205 | The Benchmark module encapsulates a number of routines to help you | |
206 | figure out how long it takes to execute some code. | |
207 | .PP | |
208 | timethis \- run a chunk of code several times | |
209 | .PP | |
210 | timethese \- run several chunks of code several times | |
211 | .PP | |
212 | cmpthese \- print results of timethese as a comparison chart | |
213 | .PP | |
214 | timeit \- run a chunk of code and see how long it goes | |
215 | .PP | |
216 | countit \- see how many times a chunk of code runs in a given time | |
217 | .Sh "Methods" | |
218 | .IX Subsection "Methods" | |
219 | .IP "new" 10 | |
220 | .IX Item "new" | |
221 | Returns the current time. Example: | |
222 | .Sp | |
223 | .Vb 6 | |
224 | \& use Benchmark; | |
225 | \& $t0 = new Benchmark; | |
226 | \& # ... your code here ... | |
227 | \& $t1 = new Benchmark; | |
228 | \& $td = timediff($t1, $t0); | |
229 | \& print "the code took:",timestr($td),"\en"; | |
230 | .Ve | |
231 | .IP "debug" 10 | |
232 | .IX Item "debug" | |
233 | Enables or disable debugging by setting the \f(CW$Benchmark::Debug\fR flag: | |
234 | .Sp | |
235 | .Vb 3 | |
236 | \& debug Benchmark 1; | |
237 | \& $t = timeit(10, ' 5 ** $Global '); | |
238 | \& debug Benchmark 0; | |
239 | .Ve | |
240 | .IP "iters" 10 | |
241 | .IX Item "iters" | |
242 | Returns the number of iterations. | |
243 | .Sh "Standard Exports" | |
244 | .IX Subsection "Standard Exports" | |
245 | The following routines will be exported into your namespace | |
246 | if you use the Benchmark module: | |
247 | .IP "timeit(\s-1COUNT\s0, \s-1CODE\s0)" 10 | |
248 | .IX Item "timeit(COUNT, CODE)" | |
249 | Arguments: \s-1COUNT\s0 is the number of times to run the loop, and \s-1CODE\s0 is | |
250 | the code to run. \s-1CODE\s0 may be either a code reference or a string to | |
251 | be eval'd; either way it will be run in the caller's package. | |
252 | .Sp | |
253 | Returns: a Benchmark object. | |
254 | .IP "timethis ( \s-1COUNT\s0, \s-1CODE\s0, [ \s-1TITLE\s0, [ \s-1STYLE\s0 ]] )" 10 | |
255 | .IX Item "timethis ( COUNT, CODE, [ TITLE, [ STYLE ]] )" | |
256 | Time \s-1COUNT\s0 iterations of \s-1CODE\s0. \s-1CODE\s0 may be a string to eval or a | |
257 | code reference; either way the \s-1CODE\s0 will run in the caller's package. | |
258 | Results will be printed to \s-1STDOUT\s0 as \s-1TITLE\s0 followed by the times. | |
259 | \&\s-1TITLE\s0 defaults to \*(L"timethis \s-1COUNT\s0\*(R" if none is provided. \s-1STYLE\s0 | |
260 | determines the format of the output, as described for \fItimestr()\fR below. | |
261 | .Sp | |
262 | The \s-1COUNT\s0 can be zero or negative: this means the \fIminimum number of | |
263 | \&\s-1CPU\s0 seconds\fR to run. A zero signifies the default of 3 seconds. For | |
264 | example to run at least for 10 seconds: | |
265 | .Sp | |
266 | .Vb 1 | |
267 | \& timethis(-10, $code) | |
268 | .Ve | |
269 | .Sp | |
270 | or to run two pieces of code tests for at least 3 seconds: | |
271 | .Sp | |
272 | .Vb 1 | |
273 | \& timethese(0, { test1 => '...', test2 => '...'}) | |
274 | .Ve | |
275 | .Sp | |
276 | \&\s-1CPU\s0 seconds is, in \s-1UNIX\s0 terms, the user time plus the system time of | |
277 | the process itself, as opposed to the real (wallclock) time and the | |
278 | time spent by the child processes. Less than 0.1 seconds is not | |
279 | accepted (\-0.01 as the count, for example, will cause a fatal runtime | |
280 | exception). | |
281 | .Sp | |
282 | Note that the \s-1CPU\s0 seconds is the \fBminimum\fR time: \s-1CPU\s0 scheduling and | |
283 | other operating system factors may complicate the attempt so that a | |
284 | little bit more time is spent. The benchmark output will, however, | |
285 | also tell the number of \f(CW$code\fR runs/second, which should be a more | |
286 | interesting number than the actually spent seconds. | |
287 | .Sp | |
288 | Returns a Benchmark object. | |
289 | .IP "timethese ( \s-1COUNT\s0, \s-1CODEHASHREF\s0, [ \s-1STYLE\s0 ] )" 10 | |
290 | .IX Item "timethese ( COUNT, CODEHASHREF, [ STYLE ] )" | |
291 | The \s-1CODEHASHREF\s0 is a reference to a hash containing names as keys | |
292 | and either a string to eval or a code reference for each value. | |
293 | For each (\s-1KEY\s0, \s-1VALUE\s0) pair in the \s-1CODEHASHREF\s0, this routine will | |
294 | call | |
295 | .Sp | |
296 | .Vb 1 | |
297 | \& timethis(COUNT, VALUE, KEY, STYLE) | |
298 | .Ve | |
299 | .Sp | |
300 | The routines are called in string comparison order of \s-1KEY\s0. | |
301 | .Sp | |
302 | The \s-1COUNT\s0 can be zero or negative, see \fItimethis()\fR. | |
303 | .Sp | |
304 | Returns a hash of Benchmark objects, keyed by name. | |
305 | .IP "timediff ( T1, T2 )" 10 | |
306 | .IX Item "timediff ( T1, T2 )" | |
307 | Returns the difference between two Benchmark times as a Benchmark | |
308 | object suitable for passing to \fItimestr()\fR. | |
309 | .IP "timestr ( \s-1TIMEDIFF\s0, [ \s-1STYLE\s0, [ \s-1FORMAT\s0 ] ] )" 10 | |
310 | .IX Item "timestr ( TIMEDIFF, [ STYLE, [ FORMAT ] ] )" | |
311 | Returns a string that formats the times in the \s-1TIMEDIFF\s0 object in | |
312 | the requested \s-1STYLE\s0. \s-1TIMEDIFF\s0 is expected to be a Benchmark object | |
313 | similar to that returned by \fItimediff()\fR. | |
314 | .Sp | |
315 | \&\s-1STYLE\s0 can be any of 'all', 'none', 'noc', 'nop' or 'auto'. 'all' shows | |
316 | each of the 5 times available ('wallclock' time, user time, system time, | |
317 | user time of children, and system time of children). 'noc' shows all | |
318 | except the two children times. 'nop' shows only wallclock and the | |
319 | two children times. 'auto' (the default) will act as 'all' unless | |
320 | the children times are both zero, in which case it acts as 'noc'. | |
321 | \&'none' prevents output. | |
322 | .Sp | |
323 | \&\s-1FORMAT\s0 is the \fIprintf\fR\|(3)\-style format specifier (without the | |
324 | leading '%') to use to print the times. It defaults to '5.2f'. | |
325 | .Sh "Optional Exports" | |
326 | .IX Subsection "Optional Exports" | |
327 | The following routines will be exported into your namespace | |
328 | if you specifically ask that they be imported: | |
329 | .IP "clearcache ( \s-1COUNT\s0 )" 10 | |
330 | .IX Item "clearcache ( COUNT )" | |
331 | Clear the cached time for \s-1COUNT\s0 rounds of the null loop. | |
332 | .IP "clearallcache ( )" 10 | |
333 | .IX Item "clearallcache ( )" | |
334 | Clear all cached times. | |
335 | .IP "cmpthese ( \s-1COUNT\s0, \s-1CODEHASHREF\s0, [ \s-1STYLE\s0 ] )" 10 | |
336 | .IX Item "cmpthese ( COUNT, CODEHASHREF, [ STYLE ] )" | |
337 | .PD 0 | |
338 | .IP "cmpthese ( \s-1RESULTSHASHREF\s0, [ \s-1STYLE\s0 ] )" 10 | |
339 | .IX Item "cmpthese ( RESULTSHASHREF, [ STYLE ] )" | |
340 | .PD | |
341 | Optionally calls \fItimethese()\fR, then outputs comparison chart. This: | |
342 | .Sp | |
343 | .Vb 1 | |
344 | \& cmpthese( -1, { a => "++\e$i", b => "\e$i *= 2" } ) ; | |
345 | .Ve | |
346 | .Sp | |
347 | outputs a chart like: | |
348 | .Sp | |
349 | .Vb 3 | |
350 | \& Rate b a | |
351 | \& b 2831802/s -- -61% | |
352 | \& a 7208959/s 155% -- | |
353 | .Ve | |
354 | .Sp | |
355 | This chart is sorted from slowest to fastest, and shows the percent speed | |
356 | difference between each pair of tests. | |
357 | .Sp | |
358 | c<cmpthese> can also be passed the data structure that \fItimethese()\fR returns: | |
359 | .Sp | |
360 | .Vb 2 | |
361 | \& $results = timethese( -1, { a => "++\e$i", b => "\e$i *= 2" } ) ; | |
362 | \& cmpthese( $results ); | |
363 | .Ve | |
364 | .Sp | |
365 | in case you want to see both sets of results. | |
366 | .Sp | |
367 | Returns a reference to an \s-1ARRAY\s0 of rows, each row is an \s-1ARRAY\s0 of cells from the | |
368 | above chart, including labels. This: | |
369 | .Sp | |
370 | .Vb 1 | |
371 | \& my $rows = cmpthese( -1, { a => '++$i', b => '$i *= 2' }, "none" ); | |
372 | .Ve | |
373 | .Sp | |
374 | returns a data structure like: | |
375 | .Sp | |
376 | .Vb 5 | |
377 | \& [ | |
378 | \& [ '', 'Rate', 'b', 'a' ], | |
379 | \& [ 'b', '2885232/s', '--', '-59%' ], | |
380 | \& [ 'a', '7099126/s', '146%', '--' ], | |
381 | \& ] | |
382 | .Ve | |
383 | .Sp | |
384 | \&\fB\s-1NOTE\s0\fR: This result value differs from previous versions, which returned | |
385 | the \f(CW\*(C`timethese()\*(C'\fR result structure. If you want that, just use the two | |
386 | statement \f(CW\*(C`timethese\*(C'\fR...\f(CW\*(C`cmpthese\*(C'\fR idiom shown above. | |
387 | .Sp | |
388 | Incidently, note the variance in the result values between the two examples; | |
389 | this is typical of benchmarking. If this were a real benchmark, you would | |
390 | probably want to run a lot more iterations. | |
391 | .IP "countit(\s-1TIME\s0, \s-1CODE\s0)" 10 | |
392 | .IX Item "countit(TIME, CODE)" | |
393 | Arguments: \s-1TIME\s0 is the minimum length of time to run \s-1CODE\s0 for, and \s-1CODE\s0 is | |
394 | the code to run. \s-1CODE\s0 may be either a code reference or a string to | |
395 | be eval'd; either way it will be run in the caller's package. | |
396 | .Sp | |
397 | \&\s-1TIME\s0 is \fInot\fR negative. \fIcountit()\fR will run the loop many times to | |
398 | calculate the speed of \s-1CODE\s0 before running it for \s-1TIME\s0. The actual | |
399 | time run for will usually be greater than \s-1TIME\s0 due to system clock | |
400 | resolution, so it's best to look at the number of iterations divided | |
401 | by the times that you are concerned with, not just the iterations. | |
402 | .Sp | |
403 | Returns: a Benchmark object. | |
404 | .IP "disablecache ( )" 10 | |
405 | .IX Item "disablecache ( )" | |
406 | Disable caching of timings for the null loop. This will force Benchmark | |
407 | to recalculate these timings for each new piece of code timed. | |
408 | .IP "enablecache ( )" 10 | |
409 | .IX Item "enablecache ( )" | |
410 | Enable caching of timings for the null loop. The time taken for \s-1COUNT\s0 | |
411 | rounds of the null loop will be calculated only once for each | |
412 | different \s-1COUNT\s0 used. | |
413 | .IP "timesum ( T1, T2 )" 10 | |
414 | .IX Item "timesum ( T1, T2 )" | |
415 | Returns the sum of two Benchmark times as a Benchmark object suitable | |
416 | for passing to \fItimestr()\fR. | |
417 | .Sh ":hireswallclock" | |
418 | .IX Subsection ":hireswallclock" | |
419 | If the Time::HiRes module has been installed, you can specify the | |
420 | special tag \f(CW\*(C`:hireswallclock\*(C'\fR for Benchmark (if Time::HiRes is not | |
421 | available, the tag will be silently ignored). This tag will cause the | |
422 | wallclock time to be measured in microseconds, instead of integer | |
423 | seconds. Note though that the speed computations are still conducted | |
424 | in \s-1CPU\s0 time, not wallclock time. | |
425 | .SH "NOTES" | |
426 | .IX Header "NOTES" | |
427 | The data is stored as a list of values from the time and times | |
428 | functions: | |
429 | .PP | |
430 | .Vb 1 | |
431 | \& ($real, $user, $system, $children_user, $children_system, $iters) | |
432 | .Ve | |
433 | .PP | |
434 | in seconds for the whole loop (not divided by the number of rounds). | |
435 | .PP | |
436 | The timing is done using \fItime\fR\|(3) and \fItimes\fR\|(3). | |
437 | .PP | |
438 | Code is executed in the caller's package. | |
439 | .PP | |
440 | The time of the null loop (a loop with the same | |
441 | number of rounds but empty loop body) is subtracted | |
442 | from the time of the real loop. | |
443 | .PP | |
444 | The null loop times can be cached, the key being the | |
445 | number of rounds. The caching can be controlled using | |
446 | calls like these: | |
447 | .PP | |
448 | .Vb 2 | |
449 | \& clearcache($key); | |
450 | \& clearallcache(); | |
451 | .Ve | |
452 | .PP | |
453 | .Vb 2 | |
454 | \& disablecache(); | |
455 | \& enablecache(); | |
456 | .Ve | |
457 | .PP | |
458 | Caching is off by default, as it can (usually slightly) decrease | |
459 | accuracy and does not usually noticably affect runtimes. | |
460 | .SH "EXAMPLES" | |
461 | .IX Header "EXAMPLES" | |
462 | For example, | |
463 | .PP | |
464 | .Vb 6 | |
465 | \& use Benchmark qw( cmpthese ) ; | |
466 | \& $x = 3; | |
467 | \& cmpthese( -5, { | |
468 | \& a => sub{$x*$x}, | |
469 | \& b => sub{$x**2}, | |
470 | \& } ); | |
471 | .Ve | |
472 | .PP | |
473 | outputs something like this: | |
474 | .PP | |
475 | .Vb 4 | |
476 | \& Benchmark: running a, b, each for at least 5 CPU seconds... | |
477 | \& Rate b a | |
478 | \& b 1559428/s -- -62% | |
479 | \& a 4152037/s 166% -- | |
480 | .Ve | |
481 | .PP | |
482 | while | |
483 | .PP | |
484 | .Vb 7 | |
485 | \& use Benchmark qw( timethese cmpthese ) ; | |
486 | \& $x = 3; | |
487 | \& $r = timethese( -5, { | |
488 | \& a => sub{$x*$x}, | |
489 | \& b => sub{$x**2}, | |
490 | \& } ); | |
491 | \& cmpthese $r; | |
492 | .Ve | |
493 | .PP | |
494 | outputs something like this: | |
495 | .PP | |
496 | .Vb 6 | |
497 | \& Benchmark: running a, b, each for at least 5 CPU seconds... | |
498 | \& a: 10 wallclock secs ( 5.14 usr + 0.13 sys = 5.27 CPU) @ 3835055.60/s (n=20210743) | |
499 | \& b: 5 wallclock secs ( 5.41 usr + 0.00 sys = 5.41 CPU) @ 1574944.92/s (n=8520452) | |
500 | \& Rate b a | |
501 | \& b 1574945/s -- -59% | |
502 | \& a 3835056/s 144% -- | |
503 | .Ve | |
504 | .SH "INHERITANCE" | |
505 | .IX Header "INHERITANCE" | |
506 | Benchmark inherits from no other class, except of course | |
507 | for Exporter. | |
508 | .SH "CAVEATS" | |
509 | .IX Header "CAVEATS" | |
510 | Comparing eval'd strings with code references will give you | |
511 | inaccurate results: a code reference will show a slightly slower | |
512 | execution time than the equivalent eval'd string. | |
513 | .PP | |
514 | The real time timing is done using \fItime\fR\|(2) and | |
515 | the granularity is therefore only one second. | |
516 | .PP | |
517 | Short tests may produce negative figures because perl | |
518 | can appear to take longer to execute the empty loop | |
519 | than a short test; try: | |
520 | .PP | |
521 | .Vb 1 | |
522 | \& timethis(100,'1'); | |
523 | .Ve | |
524 | .PP | |
525 | The system time of the null loop might be slightly | |
526 | more than the system time of the loop with the actual | |
527 | code and therefore the difference might end up being < 0. | |
528 | .SH "SEE ALSO" | |
529 | .IX Header "SEE ALSO" | |
530 | Devel::DProf \- a Perl code profiler | |
531 | .SH "AUTHORS" | |
532 | .IX Header "AUTHORS" | |
533 | Jarkko Hietaniemi <\fIjhi@iki.fi\fR>, Tim Bunce <\fITim.Bunce@ig.co.uk\fR> | |
534 | .SH "MODIFICATION HISTORY" | |
535 | .IX Header "MODIFICATION HISTORY" | |
536 | September 8th, 1994; by Tim Bunce. | |
537 | .PP | |
538 | March 28th, 1997; by Hugo van der Sanden: added support for code | |
539 | references and the already documented 'debug' method; revamped | |
540 | documentation. | |
541 | .PP | |
542 | April 04\-07th, 1997: by Jarkko Hietaniemi, added the run-for-some-time | |
543 | functionality. | |
544 | .PP | |
545 | September, 1999; by Barrie Slaymaker: math fixes and accuracy and | |
546 | efficiency tweaks. Added \fIcmpthese()\fR. A result is now returned from | |
547 | \&\fItimethese()\fR. Exposed \fIcountit()\fR (was \fIrunfor()\fR). | |
548 | .PP | |
549 | December, 2001; by Nicholas Clark: make \fItimestr()\fR recognise the style 'none' | |
550 | and return an empty string. If cmpthese is calling timethese, make it pass the | |
551 | style in. (so that 'none' will suppress output). Make sub new dump its | |
552 | debugging output to \s-1STDERR\s0, to be consistent with everything else. | |
553 | All bugs found while writing a regression test. | |
554 | .PP | |
555 | September, 2002; by Jarkko Hietaniemi: add ':hireswallclock' special tag. | |
556 | .PP | |
557 | February, 2004; by Chia-liang Kao: make cmpthese and timestr use time | |
558 | statistics for children instead of parent when the style is 'nop'. |