[CentOS] CentOS 4.5, kernel-2.6.9-55, NTPD trouble

Mon May 21 12:48:53 UTC 2007
Michael D. Kralka <michael.kralka at kvs.com>

Robert wrote:
> Following the update this morning, NTP is failing with the same symptoms
> that I saw several years ago (pre-CentOS, I believe) when Anaconda
> mistakenly blessed my ASUS A7N8X, Athlon (CPU: AMD Athlon(tm) XP 2600+
> stepping 00) based system with an SMP kernel.  The symptom is that NTPD
> never establishes sync with a server, showing over the top jitter values.

Several years ago with a Gentoo installation I experienced an identical
problem with an ASUS A7N8X-E Deluxe motherboard, also with an AMD Athlon
XP 2600+. After a lot of experimenting, I discovered that if the FSB
Spread Spectrum feature was enabled with ACPI, spurious timer interrupts
were generated, causing the system (Linux) clock to tick fast and ntpd
to fail to sync with any time source.

Who knows whether a BIOS update will fix this problem, but a quick test
would be to disable the FSB Spread Spectrum feature and see if that
fixes the problem.