> Acorn clearly wanted PMT on their earlier machines, but kept failing trying.
Ah, but in kernel land we have preemption and reentrency (just to prove it, even with a fully frozen desktop, network and disc drive still work). So Acorn manage to make kernel level things with PMT, but not user applications ? They manage to make RISC iX with PMt but not ROS ?
Perhaps after all...
> The multiple model of which you speak is a little pointless - that's
> exactly what priorities are for under PMT systems. (Or even
> dynamically adapting priorities, like Linux's)
Ah no, you cannot make a predictable system with PMT. At the best you'll make a soft or a hard RT system... That's not 100% predicatable. Why do you think Montavista tried to put different schedulers inside Linux kernel ?