math.log() benchmark of first 1 billion int using std.parallelism

[John Colvin via Digitalmars-d-learn]

On Tuesday, 23 December 2014 at 10:20:04 UTC, Iov Gherman wrote:
>> That's very different to my results.
>>
>> I see no important difference between ldc and dmd when using 
>> std.math, but when using core.stdc.math ldc halves its time 
>> where dmd only manages to get to ~80%
>
> I checked again today and the results are interesting, on my pc 
> I don't see any difference between std.math and core.stdc.math 
> with ldc. Here are the results with all compilers.
>
> - with std.math:
> dmd: 4 secs, 878 ms
> ldc: 5 secs, 650 ms
> gdc: 9 secs, 161 ms
>
> - with core.stdc.math:
> dmd: 5 secs, 991 ms
> ldc: 5 secs, 572 ms
> gdc: 7 secs, 957 ms

These multi-threaded benchmarks can be very sensitive to their 
environment, you should try running it with nice -20 and do 
multiple passes to get a vague idea of the variability in the 
result. Also, it's important to minimise the number of other 
running processes.