[fpc-pascal] Optimal number of threads for SMP

[Marco van de Voort]

In our previous episode, Mark Morgan Lloyd said:
> > Hyperthreading doubles the execution stream logic, so that one core can
> > take two incoming streams of instructions. The idea is that when one thread
> > stalls, or executes unoptimal code, the other thread can run, increasing
> > utilization. But that is more something like 10%, not doubling it.
> 
> I'd expect somewhat better than 10%,

It's a bit low. It is more like 15%. Based on kernel compile benchmarks
on phoronix.com done with and without HT.