Re: Scheduler set to 1000Hz

Matti Aarnio (matti.aarnio@sonera.fi)
Fri, 22 Jan 1999 15:15:17 +0200 (EET)


Quantum Porcupine <joshagam@cs.nmsu.edu> replied thus:
> On Fri, 22 Jan 1999, Matti Aarnio wrote:
...
> > That is elementary. The running time counts are in JIFFIES,
> > which are in the HZ units. The 'ps' has 'HZ' compiled in
> > when it was made. In fact the system does not tell the internal
> > HZ value out in any easy to use way. So sad.
>
> Ah, I see... is there any way for the ps/top/etc. utilities to get at the
> HZ rate so this behaviour can be fixed?

POSIX way would be to have sysconf() call to extract this information.
Linus' earlier comments (mid December?) ignoring, I do think Linux would
benefit from the sysconf() / pathconf() / fpathconf() trio.
Apparently *only* SPARC systems have it. (For SunOS compability.)

It is somewhat difficult to modifying presentation machinery of some
values in e.g. /proc/123/stat "file" to scale them so that they always
present their value as if the HZ would be the ``classical constant''
for given platform. For example, where would the ``classical constant''
be taken from, if the only instance of ``HZ'' is modified ?

In this case the deprecated sysconf(_SC_CLK_TCK) would be THE answer
to solve the problems that ps/top/et.al. have.

/Matti Aarnio <matti.aarnio@sonera.fi>

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