[ntp:questions] ntpd (4.2.2p1) stays "synchronized to LOCAL"

Jordan Russell jr at no.email.please
Wed Dec 6 04:46:23 UTC 2006

Richard B. Gilbert wrote:
> How badly does the clock drift if ntpd is not running?  If it's still 
> ten minutes per day, you either have a severe hardware problem or a 
> software problem that is causing your system to lose timer interrupts.

Thanks for responding.

Yes, it turns out the problem had nothing to do with ntpd after all. It
seems that starting in Linux 2.6.18, the CPU's time stamp counter (TSC)
is used to keep time. In my case, for some unknown reason, the kernel
sometimes misdetects the CPU's TSC frequency on boot, resulting in
severe clock drift that ntpd is unable to correct.

In case anyone else is afflicted by the same problem, I've managed to
work around it by adding the following parameter to my kernel command
line in grub.conf:


This tells the kernel to use the ACPI PM timer to keep time instead of
the CPU's TSC. (From what I understand, the ACPI PM timer is what older
Linux kernels used by default.)

Jordan Russell

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