std.parallelism curious results

[Ali Çehreli via Digitalmars-d-learn]

On 10/05/2014 02:40 PM, Sativa wrote:

 >      foreach(i; thds) { ulong s = 0; for(ulong k = 0; k <
 > iter/numThreads; k++)

The for loop condition is executed at every iteration and division is an 
expensive operation. Apparently, the compiled does some optimization 
when the divisor is known at compile time.

Being 4, it is just a shift of 2 bits. Try something like 5, it is slow 
even for enum.

This solves the problem:

         const end = iter/numThreads;

         for(ulong k = 0; k < end; k++) {

Ali