parallel cost-centre profiling

[Henrique Ferreiro]

> I'm not sure it's useful to profile each Capability separately.  Threads
> migrate between Capabilities under the control of the runtime system, so you
> won't get the same results from run to run.

But even in that case, I get to know what is happening in each
capability, so I can get an idea of why a program works as expected or
doesn't.

> Perhaps what you really wanted was per-thread profiling?  But that's much
> harder -you'd need per-thread stacks.  It would be a big change to the
> profiling system, and I'm not really sure whether the benefit is worth it.

I thought about it but I think it would be too much overhead.

I got the most important pieces working (I think). The question now
is, are you interested in this? I need to polish some bits and decide
what to do with the things I have postponed because I wasn't sure what
to do and I need you opinion on these.

> Cheers,
>        Simon
>