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SubjectRe: Measured overhead of timer interrupts
On Thu, Jul 22, 1999 at 05:02:14PM +0200, Ingo Molnar wrote:
>
> On 22 Jul 1999, Andi Kleen wrote:
>
> > It is a kernel bug, HZ is not exported. Actually two, because none of
> > the /proc should have used it as units, but that cannot be fixed anymore.
>
> why cannot it be fixed?

because that would break the interface.

>
> > It is easy to add a read-only sysctl for HZ though and make netstat use
> > this, but this won't fix the trillions of other /proc parsers.
>
> we do not want to export HZ, why should we? HZ has no meaning to anything
> else than the kernel. If the kernel exports HZ-dependent values into
> /proc, then that has to be fixed. (yes it might be painful in some cases)
> HZ might even go away in future kernels - what if we start using
> nonperiodic timer interrupts?

Actually, POSIX wants it (sysconf(_SC_CLK_TCK)). glibc currently returns
the HZ value it was compiled with, but that is hardly satisfying.

I agree that the time related sysctls/proc files should be fixed, but I'm
afraid it is too late.


-Andi

--
This is like TV. I don't like TV.

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