RE: PATCH: /proc/sys/kernel/hz

From: Rolf Fokkens (
Date: Mon Jul 16 2001 - 14:24:26 EST


The macro CLOCKS_PER_SEC is used for AT_CLKTCK, and for some architectures
there actually _is_ a relationship between CLOCKS_PER_SEC and HZ, and for
some there is _not_ (linux/include/asm-*/param.h).

For i386 the relation apparently _is_ there. For IA64 there's the assumption
however that that the relation is _not_ there, the kernel assumes that it's
100 HZ for ia32 _always_. Weird.

Still leaves me wondering about procps.



-----Original Message-----
From: Andreas Jaeger []
Sent: Monday, July 16, 2001 8:34 PM
To: Rolf Fokkens
Cc: ''; '';
Subject: Re: PATCH: /proc/sys/kernel/hz

Rolf Fokkens <> writes:

> Ulrich Drepper <> writes:
>>> Some software (like procps) needs the HZ constant in the kernel. It's
>>> sometimes determined by counting jiffies during a second. The attached
> patch
>>> just "publishes" the HZ constant in /proc/sys/kernel/hz.
>>And what is wrong with
>> getconf CLK_TCK
>>or programmatically
>> hz = sysconf (_SC_CLK_TCK);
> In short: it doesn't work: it reads 100 while I changed it to 1024 in my
> kernel.

Then your kernel is broken, check AT_CLKTCK,


 Andreas Jaeger
  SuSE Labs
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