Date: Wed, 5 Feb 2003 01:20:40 -0800 (PST) From: Poul-Henning Kamp <phk@FreeBSD.org> To: all-committers@FreeBSD.org, legacy-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/i386/include clock.h src/sys/i386/i386 tsc.c Message-ID: <200302050920.h159KeQ1048771@repoman.freebsd.org>
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phk 2003/02/05 01:20:40 PST
Modified files:
sys/i386/include clock.h
sys/i386/i386 tsc.c
Log:
i386/i386/tsc.c was repo-copied from i386/isa/clock.c.
Remove all the stuff that does not relate to the TSC.
Change the calibration to use DELAY(1000000) rather than trying to check
it against the CMOS RTC, this drastically increases precision:
Using 25 samples on a Athlon 700MHz UP machine I find:
stddev min max average
CMOS 22200 Hz -74980 Hz 34301 Hz 704928721 Hz
DELAY 1805 Hz -1984 Hz 2678 Hz 704937583 Hz
(The difference between the two averages is not statistically significant.)
expressed in PPM of the frequency:
stddev min max
CMOS 31.49 PPM -106.37 PPM 48.66 PPM
DELAY 2.56 PPM 2.81 PPM 3.80 PPM
This code will not be used until a followup commit to sys/isa/clock.c
and sys/pc98/pc98/clock.c which will only happen after some field testing.
Revision Changes Path
1.195 +19 -1188 src/sys/i386/i386/tsc.c
1.44 +1 -0 src/sys/i386/include/clock.h
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