[Swift-devel] Try coaster on BG/P ?

[Mihael Hategan]

On Thu, 2008-06-19 at 22:24 -0500, Ioan Raicu wrote:
> 
> 
> Mihael Hategan wrote: 
> > There's probably a misunderstanding. Mike seemed to suggest that, when
> > using BG/P, there should be multiple services in order to distribute
> > load. 
> Yes, he was correct.
> > That I think is a problem. 
> I don't follow.  If your goal is to just show that it works at small
> scales (100s, maybe 1000s of CPUs), you don't need this, but if you
> want to have any chance of scaling to 160K CPUs, I don't think you'll
> have many options :(

If your service scales linearly, then splitting it into multiple
processes does not help. But now you have more services to maintain.
That's because k*n = c*k*(n/c), where k would be your linearity factor.
If you have worse, say k*n^2, then dividing makes sense because
c*k*((n/c)^2) = k*n/c, which is better than k*(n^2).

The point is that I'd rather spend my time making the algorithm linear
than dealing with multiple services.

Now, of course, as you mention, it may not be possible to do so because
the problem is at the networking layer. So we should probably stop
talking until we know what the actual bottleneck is. And I mean *know*.
Do we?