Archive for the 'Linux' Category
April 12th, 2008 - Clock skew
So I was working on my Linux box (ArchLinux x86_64) and I notice it’s 5:15 pm which struck me as odd because I could have sworn it was later. It turned out that my NTP server was no longer functioning and it wasn’t synchronizing the clock on a regular basis. How can a modern computer manage to accumulate 30 minutes of clock skew since it was last synchronized (this morning), I wondered.
As it turns out, the timer the kernel was using (TSC) wasn’t playing nice with multiple cores and ended up falling behind around 1.85 seconds every minute. Adding “notsc” to the kernel parameters in /boot/grub/menu.lst, causing the kernel to use another timer (HPET in my case), fixed the problem.