Re: Why HZ on i386 is 100 ?

Olaf Fraczyk
2002-04-16T10:11:03Z

On 2002.04.16 12:29 Liam Girdwood wrote:
> On Tue, 2002-04-16 at 09:18, BALBIR SINGH wrote:
> > I remember seeing somewhere unix system VII used to have HZ set to
> 60
> > for the machines built in the 70's. I wonder if todays pentium iiis
> and ivs
> > should still use HZ of 100, though their internal clock is in GHz.
> >
> > I think somethings in the kernel may be tuned for the value of HZ,
> these
> > things would be arch specific.
> >
> > Increasing the HZ on your system should change the scheduling
> behaviour,
> > it could lead to more aggresive scheduling and could affect the
> > behaviour of the VM subsystem if scheduling happens more frequently.
> I am
> > just guessing, I do not know.
> >
>
> I remember reading that a higher HZ value will make your machine more
> responsive, but will also mean that each running process will have a
> smaller CPU time slice and that the kernel will spend more CPU time
> scheduling at the expense of processes.
>
Has anyone measured this?
This shouldn't be a big problem, because some architectures use value
1024, eg. Alpha, ia-64.
And todays Intel/AMD 32-bit processors are as fast as Alpha was 1-2
years ago.

Regards,

Olaf