Unsurprising. When the bodies of the iterator loops is doing next to nothing, or actually nothing, when Benchmark does it initial timings of them in order to calculate the number of iterations to run it for, it attempts to subtract a small amont to account for the overhead of the loop itself, with the result that the calculation are probably being subjected to rounding errors.
Bingo. Exactly the reason I don't use Benchmark.
When it takes 84 million iterations of a test to accumulate 1 second of cpu on a modern processor, it certainly indicates that something is wrong with your benchmark.
I wanted to show an example where a recent version of Benchmark still produces negative numbers. Knowing that the chance of finding a benchmark producing negative numbers is higher on tests that don't take much time, I picked such a test.
This is why I tend to incorprate for loops within the test when benchmarking very small pieces of code, rather than relying on the benchmark iteration count.
This is why I don't bother with Benchmark at all; if I'm going to write my own loops, I don't need a module to subtract two time stamps for me.
In reply to Re^6: &1 is no faster than %2 when checking for oddness. (Careful what you benchmark)
by Anonymous Monk
in thread &1 is no faster than %2 when checking for oddness. Oh well.
by diotalevi
| For: | Use: | ||
| & | & | ||
| < | < | ||
| > | > | ||
| [ | [ | ||
| ] | ] |