[phobos] std.parallelism: Request for review/comment

[David Simcha]

  On 8/31/2010 6:22 AM, Lars Tandle Kyllingstad wrote:
> Point (3) is pretty cool.  I just used your module for my current
> project at work, and the ability to get the index made the code a lot
> nicer.
>
> Another question:  Why have you chosen the default number of work units
> to be just two units per thread?  In my experience, it's not uncommon
> that calculations are harder on some parts of the range than others, and
> then there is a risk of some cores running out of work to do.  I'd think
> that having more work units, 3-4 per thread, say, would allow for better
> distribution of work between cores.
>
> -Lars

Good point.  I should probably change this, as the more I think about it 
the more I realize that I never use the default for the reason you 
mention.  It seemed like a good idea in iteration 1, and then I just 
never reconsidered.