On Tue, 1 Nov 2016, Markus Gothe wrote: > I doubt that it changes spontaneously. > > AFAIU this is related to NTP (the issue only shows up when setting time with ntpdate), and > time drift is a know circumstance which must be mitigated as described by Larry Doolittle and his rate.awk-scrip. You mean you can compensate when suddenly 1 second of system time is only elapsed after 8-9 wall clock seconds? I seriously doubt it. What it looks like to me is some sort of an interrupt delivery or reprogramming issue with the CP0 Count/Compare timer, which as you may recall is a one-shot event and needs rearming. But it's not worth looking into with a kernel which is 8 years old. It may well have been the time around which our CP0 timer suport was converted to the HPT framework and new code could have suffered from infancy bugs. Switching to another clock source might be a workaround if available with the system being used, e.g. the Malta board has an 8254 PIT clone in the south bridge wired to an interrupt line, which can be used in its periodic mode. I'm not sure offhand if the PIT clock source is configured though in a pristine Malta kernel; it may well be that nobody cared to arrange that, given the arcane programming interface and the limited resolution of the PIT and the general availability of the CP0 timer. And then we might not be talking about a Malta anyway. Maciej
