[mdlug] Clocks

[Aaron Kulkis]

Joe Doehler wrote:
> Carl T. Miller wrote:
>> Joe Doehler wrote:
>> ...
>>
>>> That was it! I had to change the clock source. I edited grub.conf to
>>> make the change stick across reboots. Thanks.
>>>
>>> All that's left for me to is to tell the system to stop messing with the
>>> hardware clock during shutdowns, so that ntpd can do its job properly.
>> Joe, this is the first I've heard of this.  What clock
>> source were you using before and what did you change it to?
>> ...
> 
> There are three clock sources available on my system, called "pit", 
> "jiffies" and "tsc". I found them following Ron's post. The installation 
> program selected "pit", that seems to be the preferred one when using 
> "VMware". I changed it to "tsc", and the system clock is now tracking 
> the hardware clock. "jiffies" had the same problem. I have no idea what 
> the difference is between them. I expect that ntps will now be able to 
> handle hardware clock drifts.


Jiffies is a cpu-dependant method to keep time based totally
on software and an interrupt timer.  NEVER use this method unless
no other method is even possible -- computers are notoriously
horrible at keeping time properly  That's why there's a hardware
clock on the motherboard.  As horrid as those things are, they
vastly superior to the jiffies method.