Kernel clock issue "Clocksource tsc unstable"

[NoOp]

On 02/27/2009 12:39 PM, Rashkae wrote:
> Ray Parrish wrote:
> 
>> Hello,
>> 
>> Sorry to butt in here, but I also receive the error messages about 
>> clocksource tsc being unstable. I ran the command for available 
>> clocksources and got the following output. "acpi_pm pit jiffies tsc" My 
>> system switches to acpi_pm after the error message, but I would like to 
>> read about the other available clocksource files before making a 
>> decision on which to try to use from the menu.lst file.

I have old laptops that use acpi_pm rather than tsc, but I sync the time
to an ntp server so I don't ever have any problems with them. Dmesg on
those read something along the line of:
Clocksource tsc unstable(deslta = -87685142 ns)

> 
> Sorry, this is really deep magic stuff where mortals were really never
> meant to thread.  You practically have to dig through the kernel source
> to find any scraps of useful information.  I just got a crash course
> about 6 months ago when I was trying to solve a clock drift issue.  I'll
> try to provide the cliff notes, but keep in mind, this is just my
> understanding of things and I might be wrong about a fact or 2.

I recall that thread:
http://comments.gmane.org/gmane.linux.ubuntu.user/145397
[Computer loosing time]
might be worth looking at again.

[snips rest of excellent info]

I wonder if perhaps when Hal reboots his machines the reason why the
clocks/dates get readjusted properly is because the boot causes the
ntpdata script to run:

/etc/network/if-up.d/ntpdate

and hence resync?

@Hal: next time, instead of rebooting (you'll still have to go to the
data center most likely), you might try
sudo /etc/network/if-up.d/ntpdate
first. If that resyncs the machine properly without the reboot, then you
might want to look into running ntp on those machines if you aren't
already. And if you are running ntp, have a look at the ntp source. You
can elect to have multiple sources; I use 0.us.pool.ntp.org and have
1.us.pool.ntp.org as the backup. Just a thought...