diff options
Diffstat (limited to 'lib/Benchmark.pm')
| -rw-r--r-- | lib/Benchmark.pm | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Benchmark.pm b/lib/Benchmark.pm index 1d272a7d33..90e54a66ee 100644 --- a/lib/Benchmark.pm +++ b/lib/Benchmark.pm @@ -904,6 +904,16 @@ sub timethis{ $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 verses 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! |