On the other hand, if a user requires better resolution,
s/he just turns on the high-res option and incures the
overhead only when it is used and then only at timer expire
time. Note that the only way to access a high-res timer is
via the POSIX clocks and timers API. They are not available
to select or any other system call.
Making ticks shorter causes extra overhead ALL the time,
even when it is not needed. Higher resolution is not free
in any case, but it is much closer to free with this patch
than by increasing HZ (which, of course, can still be
done). Overhead wise and resolution wise, for timers, we
would be better off with a 1/HZ tick and the "on demand"
high-res interrupts this patch introduces.
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/