On Mon, 27 Aug 2007, Lonni J Friedman wrote:
The timer in /proc/interrupts was not changing, and neither was the
timestamp in /proc/schedstat. ugh.
Sorry for the confusion. Andy Green's posts clear this up and hopefully
this will clarify somewhat too.
For aeon's, well maybe centuries, ok really just decades the majority of
OS'es that run on PC's used IRQ0 to update the real time clock. What this
means is that 100 times a second (100 Hz) the kernel (in the case of
linux) is interrupted and the real time clock is updated among other
things then the kernel goes about it's business. To get better resolution
the 100 Hz parameter is changeable at compile time to 100, 250 or 1000 (I
believe). I think it defaulted to 1000Hz recently. In any case as Andy
Green pointed out modern kernels have gone "tickless". This is a very
good thing for laptops and saving power etc.
From what I have read HPET or High Precision Event Timer is what is used
now (in the 2.6.21 or so kernel timeframe and beyond). HPET is a device
that is part of the chipsets on modern motherboards. From what I've been
told the HPET code is broken in some kernel versions (I mean hey it's
brand new code, sure could be buggy).
So to the original poster (Lonni J Friedman?) I'd suggest (as Andy
mentioned) check to see what your clocksource is:
cat /sys/devices/system/clocksource/clocksource0/current_clocksource
If it says 'hpet' reboot your machine and pass 'hpet=disable' to the
kernal via grub. I don't have a machine that I can reboot at the moment,
but IIRC at the grub prompt you press 'e' to edit the command before
booting. From there I forget but google should help find the syntax. Or
perhaps it's even self explanatory.
In any case this should force your machine to keep time the old fashioned
way which unless you're on a laptop should be just fine. And if this
works you can edit grub.conf (I believe) and 'hpet=disable' to make this
permanent.
-- Mike
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