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From: Robert Watson <rwatson@FreeBSD.org>
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To: "M. Warner Losh" <imp@bsdimp.com>
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Cc: phk@phk.freebsd.dk, freebsd-current@freebsd.org
Subject: Re: TSC instead of ACPI: powerd doesn't work anymore (to be
	expected?)
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On Mon, 31 Oct 2005, M. Warner Losh wrote:

> In message: <81213.1130754398@critter.freebsd.dk>
>            "Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
> : I am going to insist that clock_gettime(CLOCK_REALTIME, CLOCK_UPTIME)
> : remain precise.
>
> 1ms is way too imprecise for the stuff we do at work.  We need 3-4 more 
> orders of magnitude at a minimum from the time keeping system. Ideally, 
> through well documented interfaces.

While I agree that for many consumers, sub-1ms accuracy is too low, I 
suggest that as a vendor of atomic clocks, your company is in fact not the 
average consumer of timing information. :-).

One nice thing about the Linux TSC model, despite its limitations, is that 
it provides a middle ground between incrementing the clock in ticks and 
providing a more continuous measure of time, by allowing interpolation 
between ticks.

Robert N M Watson