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Date:      Thu, 06 Feb 2003 08:20:29 +0100
From:      phk@freebsd.org
To:        Bruce Evans <bde@zeta.org.au>
Cc:        "Greg 'groggy' Lehey" <grog@freebsd.org>, all-committers@freebsd.org, legacy-committers@freebsd.org, cvs-all@freebsd.org
Subject:   Re: cvs commit: src/sys/i386/include clock.h src/sys/i386/i386 tsc.c 
Message-ID:  <52866.1044516029@critter.freebsd.dk>
In-Reply-To: Your message of "Thu, 06 Feb 2003 18:18:31 %2B1100." <20030206174018.R72201-100000@gamplex.bde.org> 

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In message <20030206174018.R72201-100000@gamplex.bde.org>, Bruce Evans writes:

>However, precise measurements of these clocks turn out to be essentially
>useless except probably for phk's nonstandard hardware, since the
>accuracy of these clocks is much worse than their precision.  Drift of
>10-100 parts per million for a 10 degree temperature change is normal.
>So calibrations more precise than this are not useful.

Actually, things have improved, and motherboard crystals are now
generally no worse than +/-1 PPM/K.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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