I found some lines in dmesg that might be related to the problem: CPI: PM-Timer IO Port: 0x4008 time.c: Using 3.579545 MHz WALL PM GTOD PIT/TSC timer. time.c: Detected 1794.962 MHz processor. Calibrating delay using timer specific routine.. 3593.32 BogoMIPS (lpj=7186655) Using local APIC timer interrupts. Detected 12.465 MHz APIC timer. Real Time Clock Driver v1.12ac Your time source seems to be instable or some driver is hogging interupts