[ale] Solved - Re: Issues with NTP - synchronizes, then falls behind...

[Jason Fritcher]

On Jul 26, 2009, at 12:53 PM, Chris Woodfield wrote:
> tino:~# cat /sys/devices/system/clocksource/clocksource0/
> available_clocksource
> tsc hpet acpi_pm jiffies

TSC - Timestamp Counter, this clock is based on the clock frequency of  
the cpu, can vary over time if the cpu clock drifts or on laptops is  
changed because of power managment.

HPET - High Precision Event Time, this is a high performance timer  
that is being used on newer MBs, but older boards do not have it.

ACPI_PM - ACPI Power Management, this clock is specified as part of  
the ACPI spec and seems to be fairly reliable these days, but on older  
MBs, this clock wasn't always reliable.

Jiffies - I would presume that his is based on the software timings  
calculated at boot time. I'm sure this is pretty unreliable.

Out of all of these, hpet would be the most accurate, but might not be  
available, next would be the acpi_pm and then tsc.

If I managed to mess any of the above up, please let me know. :)

-- 
Jason Fritcher
jkf at wolfnet.org