--make should have a -j flag for parallel building

[igloo]

It should be possible to give --make a -j flag, similar to make's, to tell it to use multiple proceses to build modules. This would allow executables, libraries and cabal packages to be built faster for people with multiple CPUs.

[simonmar]

This seems like a good place to hang my patch to implement ghc --make -jN, which was used for the experiments in the 2005 Haskell Workshop paper on SMP GHC, but almost certainly isn't ready for prime time.

[bos]

Would love to have this.

[simonmar]

Not for 6.8, probably.

[simonmar]

We're not planning this for 6.10. It's more likely that Cabal will get parallel make support first, in which case there's less need for us to tackle this.