From: Gurusamy Sarathy <gsar@cpan.org>
Date: Fri, 15 Oct 1999 01:34:09 +0000 (+0000)
Subject: Benchmark notes (from Barrie Slaymaker <barries@slaysys.com>)
X-Git-Tag: accepted/trunk/20130322.191538~35965
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=54e82ce5cfd72fcdc60806373e0c4d6890b68a3c;p=platform%2Fupstream%2Fperl.git

Benchmark notes (from Barrie Slaymaker <barries@slaysys.com>)

p4raw-id: //depot/perl@4384
---

diff --git a/lib/Benchmark.pm b/lib/Benchmark.pm
index 9196673..83331aa 100644
--- a/lib/Benchmark.pm
+++ b/lib/Benchmark.pm
@@ -269,6 +269,35 @@ calls like these:
 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;$x=3;cmpthese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
+
+outputs something like this:
+
+   Benchmark: running a, b, each for at least 5 CPU seconds...
+	    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%   --
+
+while 
+
+   use Benchmark;
+   $x=3;
+   $r=timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}},'none');
+   cmpthese($r);
+
+outputs something like this:
+
+          Rate    b    a
+   b 1559428/s   -- -62%
+   a 4152037/s 166%   --
+
+
 =head1 INHERITANCE
 
 Benchmark inherits from no other class, except of course
diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index b4d4d21..3ff77cc 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -1035,25 +1035,43 @@ The Dumpvalue module provides screen dumps of Perl data.
 
 =item Benchmark
 
+Overall, Benchmark results exhibit lower average error and better timing
+accuracy.  
+
 You can now run tests for I<n> seconds instead of guessing the right
 number of tests to run: e.g. timethese(-5, ...) will run each 
 code for at least 5 CPU seconds.  Zero as the "number of repetitions"
 means "for at least 3 CPU seconds".  The output format has also
 changed.  For example:
 
-use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
+   use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
 
 will now output something like this:
 
-Benchmark: running a, b, each for at least 5 CPU seconds...
-         a:  5 wallclock secs ( 5.77 usr +  0.00 sys =  5.77 CPU) @ 200551.91/s (n=1156516)
-         b:  4 wallclock secs ( 5.00 usr +  0.02 sys =  5.02 CPU) @ 159605.18/s (n=800686)
+   Benchmark: running a, b, each for at least 5 CPU seconds...
+            a:  5 wallclock secs ( 5.77 usr +  0.00 sys =  5.77 CPU) @ 200551.91/s (n=1156516)
+            b:  4 wallclock secs ( 5.00 usr +  0.02 sys =  5.02 CPU) @ 159605.18/s (n=800686)
 
 New features: "each for at least N CPU seconds...", "wallclock secs",
 and the "@ operations/CPU second (n=operations)".
 
-change#4265,4266,4292
-[TODO - Barrie Slaymaker <barries@slaysys.com>]
+timethese() now returns a reference to a hash of Benchmark objects containing
+the test results, keyed on the names of the tests.
+
+timethis() now returns the iterations field in the Benchmark result object
+instead of 0.
+
+timethese(), timethis(), and the new cmpthese() (see below) can also take
+a format specifier of 'none' to suppress output.
+
+A new function countit() is just like timeit() except that it takes a
+TIME instead of a COUNT.
+
+A new function cmpthese() prints a chart comparing the results of each test
+returned from a timethese() call.  For each possible pair of tests, the
+percentage speed difference (iters/sec or seconds/iter) is shown.
+
+For other details, see L<Benchmark>.
 
 =item Devel::Peek