Subject: Re: port-i386/1835: Kernel compile dies in machdep.c if HZ is
To: None <netbsd-bugs@NetBSD.ORG>
From: Leo Weppelman <>
List: netbsd-bugs
Date: 12/14/1995 16:44:00
> > For the i386 port, I could not compile a kernel with HZ defined.
> > (I am not sure if one is supposed to, but I wanted /kern/hz to be
> > the speed of my processor, not 100.)
> I think one is not supposed to; HZ and associated values are supposed
> to be the number of times per second the time-of-day clock ticks, which
> on most machines is not a number you can casually change.
> At least, that's how I always understood it.
It is not something you should do just for fun and dependend on the 
implementation of the system clock, it might be that only some values
are permitted. If the value of HZ you select cannot be made from the
crystal-freq. without rounding errors, the system time will be drifting.
There are valid reasons I can think of to fiddle with HZ like reducing
clock overhead or increasing profiling granularity.

Just wondering.... Why would you set HZ to the speed of your processor 
(divided by 1MHz I hope!)?