> I will agree that it increases the unpredictability of execution time,
> and if I wanted to guarantee I could meet deadlines I'd turn it off.
Turning it off may indeed improve predictability of execution time in
some cases. Especially if the various active threads have different
real-time priorities.
For non-real-time threads, turning it off would just replace the
hardware's scheduler unpredictability with that of the OS.
For really hard real-time, of course, you still have many other sources
of unpredictability: the cache(s), the TLB, the branch prediction, ...
Stefan
