Re: [PATCH] i386: fix TSC clock source calibration error

From: Charles R Harris
Date: Fri Oct 19 2007 - 14:48:53 EST


On Tue, 2007-10-16 at 10:50 -0400, Dave Johnson wrote:
>
> range of tsc_khz # of boots % of boots
> ----------------- ---------- ----------
> < 1999750 0 0.000%
> 1999750 - 1999800 21 3.048%
> 1999800 - 1999850 166 24.128%
> 1999850 - 1999900 241 35.029%
> 1999900 - 1999950 211 30.669%
> 1999950 - 2000000 42 6.105%
> 2000000 - 2000000 0 0.000%
> 2000050 - 2000100 0 0.000%
> [...]
> 2000100 - 2015000 1 0.145% << BAD
> 2015000 - 2030000 6 0.872% << BAD
> 2030000 - 2045000 1 0.145% << BAD
> 2045000 < 0 0.000%
>
> The worst boot was 2032.577 Mhz, over 1.5% off!

This may be related to bug
https://bugzilla.redhat.com/show_bug.cgi?id=270321 at Redhat bugzilla.
It has been easily reproducible on my machine.

Chuck
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