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Date:      Mon, 8 Sep 1997 09:24:11 +0800 (CST)
From:      Hoffmann Yen-Wei Liu <ywliu1@tao.sinanet.com.tw>
To:        question@freebsd.org
Cc:        hackers@freebsd.org
Subject:   Kernel clock runs inaccurately
Message-ID:  <199709080124.JAA14004@tao.sinanet.com.tw>

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Hi,

  Sorry, I don't know if this question fits in questions or hackers 
mailing list.

  I just got myself a new AMD k6-200, and I found out a major problem :
it runs about 30 seconds faster per day. So two days later, it runs
2 minutes faster. However, the CMOS clock runs around 2 seconds slower
per day. This is acceptable to me.

  After fooling around with CLK_USE_I8254_CALIBRATION and 
CLK_USE_I586_CALIBRATION options, I can either make it run 2 seconds slower
per *hour*, or several seconds faster per minutes, but not to a acceptably
inaccurate ranage. The boot verbose flag gives me the following figure inf:

...
Calibrating clock(s) ... i586 clock: 199932094 Hz, i8254 clock: 1194681 Hz
Calibrating clock(s) ... i586 clock: 199931374 Hz, i8254 clock: 1194663 Hz
CPU: AMD K6 (199.93-MHz 586-class CPU)
  Origin = "AuthenticAMD"  Id = 0x561  Stepping=1
  Features=0x8001bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
...


Also, even looking into isa/i386/clock.c cannot give me too many clues.

In a word,

1) I know Pentium motherboard clock isn't accurate. But is there any workaround
for me to set options or modify clock.c to make the kernel clock runs in
a acceptably inaccurate range ?

2) Does changing to a new motherboard with better quality help ?

3) I run OSS/FreeBSD commercial sound driver. Does this possibly matter ?


THanks for your attention.


Yen-Wei Liu



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