Messages in this thread | | | Date | Sun, 22 Feb 2009 20:11:52 -0800 (PST) | Subject | Re: x86's nmi_hz wrt. oprofile's nmi_timer_int.c | From | David Miller <> |
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From: Andi Kleen <andi@firstfloor.org> Date: Sun, 22 Feb 2009 18:06:45 +0100
> David Miller <davem@davemloft.net> writes: > > Really old mail, but I was very behind. I didn't see an > correct answer, so let's answer it. > > > While working on an NMI watchdog implementation on sparc64 > > I noticed what seems to be a peculiar behavior of the NMI > > timer int oprofile support on x86. > > > > When the NMI watchdog tests itself at boot timer we start > > with nmi_hz equal to HZ. > > > > After the NMI watchdog self-test passes, nmi_hz is reduced > > down to '1'. > > > > The NMI timer int oprofile support simply uses DIE_NMI notifiers for > > it's implementation. But I don't see anything in the code of > > arch/x86/oprofile/nmi_timer_int.c nor the NMI watchdog infrastructure > > which will re-adjust nmi_hz back to HZ or something similar. > > > > Am I missing something? > > oprofile generates its own NMIs, it does not rely on > the ones from the nmi watchdog.
The code in nmi_timer_int.c doesn't.
> In timer mode it does not use nmis or die notifiers, but relies on the > regular non nmi timer interrupt.
Again, the code in nmi_timer_int.c doesn't.
It uses the NMI watchdog timer interrupts, it catches DIE_NMI events.
> Does that answer your question?
Not really.
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