Scalability in std.parallelism

[Russel Winder]

On Sun, 2014-02-23 at 22:55 -0800, Ali Çehreli wrote:
[…]
> On my quad-core Intel I get the following (I have two actual cores, four 
> hyperthreads):
> 
> 3.14159 took 441[ms]
> 3.14159 took 878[ms]
> Speedup 1.99093
> -5.80829e+09 took 98[ms]
> -5.80829e+09 took 328[ms]
> Speedup 3.34694
> 
> I am not an expect at all but it looks like the first test cannot take 
> advantage of hyperthreading but the second one can to some degree.

I'm fairly sure I don't agree with this hypothesis. Two cores with
hyperthreads generally means a maximum speed up of 2 with optimized
native code. So for me the first one looks fine whereas the second one
seems to indicate a problem in std.parallelism.

-- 
Russel.
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