Not able to get scaled performance on increasing number of threads

[Dmitry Olshansky]

01-Feb-2013 19:42, Sparsh Mittal пишет:
> It got posted before I completed it! Sorry.
>
>
> I am parallelizing a program which follows this structure:
>
> immutable int numberOfThreads= 2
>
> for iter = 1 to MAX_ITERATION
> {
>       myLocalBarrier = new Barrier(numberOfThreads+1);
>       for i= 1 to numberOfThreads
>        {
>          spawn(&myFunc, args)
>        }
>        myLocalBarrier.wait();
>
> }
>
> void myFunc(args)
> {
>       //do the task
>
>         myLocalBarrier.wait()
> }
>
> When I run it, and compare this parallel version with its serial
> version, I only get speedup of nearly <1.3 for 2 threads. When I write
> same program in Go, scaling is nearly 2.
>
> Also, in D, on doing "top", I see the usage as only 130% CPU and not
> nearly 200% or 180%. So I was wondering, if I am doing it properly.
> Please help me.


Can't tell much without the whole source or at least compilable 
standalone piece. The '//do task part' is critical to understanding as 
well as declaration of myLocalBarrier.

Also why not use std.parallelism?
-- 
Dmitry Olshansky