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Date:      Thu, 5 May 2005 10:43:30 +0200
From:      Anthony Atkielski <atkielski.anthony@wanadoo.fr>
To:        freebsd-questions@freebsd.org
Subject:   Re: Clock running fast
Message-ID:  <352039115.20050505104330@wanadoo.fr>
In-Reply-To: <34d0f02f0868350c3c07570e3a73ceef@mac.com>
References:  <42792740.3040501@houston.rr.com> <34d0f02f0868350c3c07570e3a73ceef@mac.com>

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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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