gcc build / test times on multi-core hosts?

[Mattias Engdegård]

Diego Novillo <dnovillo@redhat.com> writes:

>I/O is probably the biggest bottleneck, so if you have a fairly decent
>I/O system, you may find higher -jN numbers giving better results.

Yes, but there is also an effect in the opposite direction: higher
parallelism may compensate for slow I/O by keeping CPUs busy. My rule
of thumb, no doubt suboptimal, is to build with twice as many jobs as
there are cores.