Maximum cycling frequency of 200Hz?

[David.Hamilton@jet.uk (David Hamilton)]

I'm running RTLinux 3.1 on a PC with an AMD K6 500Mhz processor (RedHat7.1).

I seem to be only able to run a real-time loop at a maximum frequency of
200Hz.
Trying to set a lower period in pthread_make_period... or a shorter sleep in
nanosleep has no effect beyond 200Hz (5msec)!

I've read in other emails about the #define HZ 100 in the linux param.h
file, but assumed that only effected context switching within the user
space.
I've also read about people reaching rates in excess of 1KHz (I'm looking
for 1KHz).

Can anyone tell me what I have to do to get these higher frequencies, or is
it a limitation of my hardware.
David