Clock running fast

Anthony Atkielski atkielski.anthony at wanadoo.fr
Thu May 5 01:43:33 PDT 2005


Charles Swiger writes:

> Try changing the kern.timecounter.hardware sysctl; you can look at the
> available choices via:
>
>          sysctl kern.timecounter.choice

So what do the choices mean?  How are they used?

On one machine, I see TSC, ACPI-fast, i8254, and dummy as choices, and
ACPI-fast is selected (this is a P4 machine). On the other, older
machine (a 2-processor Pentium Pro), I see TSC, i8254, and dummy, and
i8254 is selected.

I presume that TSC is a real-time clock based on the processor TSC, and
I presume also that i8254 is such a clock based on the classic i8254
timer, but what is dummy, and what is ACPI-fast?

What are the pros and cons of selecting different choices?

-- 
Anthony




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