The setitimer resolution is not defined to be HZ. It is perfectly
reasonable to think that in the future, with the increase of
soft-RTism in the kernel, timers will be automagically adapted to give
the best precision available to such timers.
Face it, HZ is obsolete. You don't want a 10ms (or 1ms) resolution on
everything you do anymore. You want the shortest possible latency on
events (which mainly means rescheduling after interrupts and/or IPCs)
for good interactive behaviour. You want long timeslices on
cpu-burning processes to reduce cache effects. You want precise
timers. Saying that HZ rules them all is innefficient.
What you can reasonably do in the scheduler heavily depends on the
hardware (cost of reprogramming the timer interrupt, interrupt
latency, cache sizes...) and on the software (amount of RT-ness used
by applications, use of special priorities...). Nowadays a fixed
length timer interrupt may be the most efficient way, but in some
years, the whole HZ concept may be gone. Do you really want to rely
on it in your applications?
OG.
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