> // But do you know of any part [of Plan 9] that would be > // beneficial for highly-SMP systems?
one difference from many of the others is that plan 9, both kernel and applications, were written with multiprocessors in mind, at least up to 32 or so, so data structure locking was included as the code was written, and processes (kprocs in the kernel) were used (or not) as appropriate. generally, the granularity used seems appropriate. kernel processes can be pre-empted. there is plenty of scope for parallelism. many others started with a non-preemptible kernel and added a big global lock, and gradually, very gradually changed code to use locks at finer granularity. sometimes.
