RE: Why HZ on i386 is 100 ?

Tue, 16 Apr 2002 13:48:56 +0530

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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.

Changing though trivial would require a good look at all the code that
uses HZ.


|-----Original Message-----
|[]On Behalf Of William Lee
|Irwin III
|Sent: Tuesday, April 16, 2002 1:45 PM
|To: Olaf Fraczyk
|Subject: Re: Why HZ on i386 is 100 ?
|On Tue, Apr 16, 2002 at 09:47:48AM +0200, Olaf Fraczyk wrote:
|> Hi,
|> I would like to know why exactly this value was choosen.
|> Is it safe to change it to eg. 1024? Will it break anything?
|> What else should I change to get it working:
|> Please CC me.
|> Regards,
|> Olaf Fraczyk
|I tried a few times running with HZ == 1024 for some testing (or I guess
|just to see what happened). I didn't see any problems, even without the
|obscure CLOCKS_PER_SEC ELF business.
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