Kernel time problem 2.2.15/2.2.16

From: Richard B. Johnson (
Date: Thu Aug 31 2000 - 07:59:27 EST

Every morning at 00:00:00, I have cron set my system clock to
NIST ( Then I use hwclock to set
the hardware clock to the new system time.

# Min Hour Day Month Day_of_week Command
0 0 * * * /usr/local/sbin/nettime >>/var/adm/set_time.log;/sbin/hwclock --systohc >>/var/adm/set_time.log

`nettime` is `rdate` that shows the time before and after it's set.
This has worked very well with a relatively old version of Linux,
linux-2.2.6. The time of my server has always been within about 10
seconds of NIST.

I upgraded my server to:
Linux boneserver 2.2.15 #22 SMP Fri Aug 25 17:31:25 EDT 2000 i686

Now the time is diverging. Every night, the time is further and
further from NIST, just before it is set.

The current contents of /etc/adjtime shows that the last time hwclock
set the time, it was 394 seconds off:

        -394.634766 967724179 0.000000

This is a bit much. Water-clocks are more accurate than this.
This may be a "set-back-time" problem because the kernel thinks
that it's midnight, the time gets set back roughly 6 minutes,
then there may be a problem when it's midnight again, 6 minutes
later. Just a WAG.

Is this a known problem?
Should I just zero out or remove /etc/adjtime and see if it starts
to converge?
Should we always zero out or remove /etc/adjtime during an upgrade to handle
possible code changes?

FYI, I just deleted /etc/adjtime and created a new one with hwclock.
I will see what it does tonight.

Dick Johnson

Penguin : Linux version 2.2.15 on an i686 machine (797.90 BogoMips).

"Memory is like gasoline. You use it up when you are running. Of
course you get it all back when you reboot..."; Actual explanation
obtained from the Micro$oft help desk.

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This archive was generated by hypermail 2b29 : Thu Aug 31 2000 - 21:00:27 EST