Con Kolivas returns with a new scheduler

The real reason we used to use "make -j MORE_THAN_NR_CPUS" was to get useful work done when a process waits on I/O. Con's scheduler doesn't help with that: if gcc foo.c needs to read foo.c from disk, you must have more jobs than CPUs, or you have an idle CPU.

What's changed is nowadays most of us have enough RAM to keep the whole kernel source and object files in cache, so there's no I/O delay after the first compile of the day.

I'm surprised Con's scheduler compiles more quickly than CFS, and that has to be worth looking into.