multithread/concurrency/parallel methods and performance

[SrMordred]

On Monday, 19 February 2018 at 05:54:53 UTC, Dmitry Olshansky 
wrote:
> The operation is trivial and dataset is rather small. In such 
> cases SIMD with eg array ops is the way to go:
> result[] = values[] * values2[];

Yes, absolutely right :)

I make a simple example to understand why the threads are not 
scaling in the way i thought they would.
I imagine that, if one core work is done in 200ms a 4 core work 
will be done in 50ms, plus some overhead, since they are working 
on separate block of memory, without need of sync, and without 
false sharing, etc (at least I think i don´t have this problem 
here).