Re: NO_HZ: timer interrupt stuck [Re: Linux 2.6.21-rc1]

From: Arjan van de Ven
Date: Thu Feb 22 2007 - 09:21:14 EST

On Thu, 2007-02-22 at 15:10 +0100, Pierre Ossman wrote:
> Arjan van de Ven wrote:
> >
> > some can be used for both (PIT), but on a concept level the uses are
> > independent. The advantage of local apic over PIT is that local apic is
> > cheap to do "one shot" future events with, while the PIT will tick
> > periodic at a fixed frequency. With tickless idle.. that's not what you
> > want.
> >
> So with a local apic, and acpi_pm as clocksource, I shouldn't be getting timer
> interrupts?

timer interrupts as in "irq0"?

you shouldn't if you use the hrtimers/tickless stuff...

can you get us a dmesg somewhere? maybe the kernel mentions why ;)

> Yet I do. Which I assume means that the kernel will still get woken
> up very often.

if irq0 keeps increasing at 100Hz or 1000Hz or so.. then yes
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