Dear Adrian et al, Dave posted some KRoC Linux executables on the web: commstime (twice -- once with a PAR-delta and one with a SEQ-delta). Subtracting the times per iteration between the two gives the process start-up/shut-down cost. The context-switch overheads are quoted in Dave's mail for, I think, a 200 MHz Pentium II. I get around 370 ns (for SEQ-delta) and 430 ns (for PAR-delta) on the flash 266 MHz laptop I'm dragging (it's heavy!) to Sun with me. These overheads might be higher than expected but the kernel is NOT yet optimised. Jim Moores -- who is implementing this but is on holiday in Spain right now -- got fed up coding in 386 assembler! He now has a KRoC kernel written almost entirely in C. This made for a quicker implementation (in development time) and will make porting to strange architectures a doddle. I don't know if he's compiled his kernel with optimisation flags set yet (Jim?) but we always expected some penalty doing this compared to native assembler. A factor of 2 (it's less than that) ought to be acceptable. We could always start grafting the more heavilly used bits of the kernel into native code if really pushed! Incidentally, the KRoC/Linux system is using Michael Poole's etc-code route (reported at WoTUG-21). But never mind commstime! Have you tried the two dining philosophers codes. One you've seen before (by Nick Hollands, now a Ph.D student here) and one is from Fred Barnes (one of our current 2nd. years). Each year we make the students animate the dining philosophers. Fred won it this year. Check out what happens if you inject caffeine or poison into the spaghetti ... OK -- Holland have just equalised and my taxi comes at 5:30am tomorrow. Cheers, Peter.