How to tune numerical D? (matrix multiplication is faster in g++ vs gdc)

[Walter Bright]

On 3/4/2013 9:00 AM, John Colvin wrote:
> On Monday, 4 March 2013 at 15:44:40 UTC, bearophile wrote:
>> John Colvin:
>>
>>> The performance of the multiplication loops and the performance of the
>>> allocation are separate issues and should be measured as such, especially if
>>> one wants to make meaningful optimisations.
>>
>> If you want to improve the D compiler, druntime, etc, then I agree you have to
>> separate the variables and test them one at a time. But if you are comparing
>> languages+runtimes+libraries then it's better to not cheat, and test the whole
>> running (warmed) time.
>>
>> Bye,
>> bearophile
>
> I disagree. Information about which parts of the code are running fast and which
> are running slow is critical to optimisation. If you don't know whether it's the
> D memory allocation that's slow or the D multiplication loops, you're trying to
> optimise blindfolded.

I agree with John. Correctly interpreting benchmark results will enable you to 
tune your application to run much faster, even without any changes to the 
compiler or runtime library.