Re: HPET regression in 2.6.26 versus 2.6.25 -- question about NMIwatchdog

From: Ingo Molnar
Date: Fri Aug 15 2008 - 09:27:39 EST



* David Witbrodt <dawitbro@xxxxxxxxxxxxx> wrote:

> Quick question: a quick browse of 'Documentation/nmi_watchdog.txt'
> suggests that I should use "nmi_watchdog=1", since I have SMP (CPU =
> Athlon 64 X2, with CONFIG_SMP=y). Should I follow your suggestion
> later, or follow the recommendation of the 'nmi_watchdog.txt' doc?

you could try both, starting with nmi_watchdog=2 - and trying
nmi_watchdog=1 if that doesnt work. The problem with nmi_watchdog=1 is
that it disables high-res timers. (because it has to - it piggy-backs on
the back of a periodic timer interrupt)

you might even want to test the NMI watchdog with an intentional
user-space hard lockup - with the attached lockupcli.c program.
(Warning: if you run it as root it will really lock up your box hard.
Run it from a VGA text mode console to see any console messages.)

Ingo

main ()
{
iopl(3);
for (;;) asm("cli");
}