Re: Clocksource tsc is always unstable with 2.6.25-* kernels andCONFIG_NO_HZ=y on my box

From: Thomas Gleixner
Date: Mon Feb 25 2008 - 02:41:32 EST


On Sun, 24 Feb 2008, Robert Hancock wrote:
> Gabriel C wrote:
> > Hi,
> >
> > I noticed tsc is always marked unstable on my box with 2.6.25* , 2.6.24 is
> > fine.
> >
> > ..
> >
> > [ 0.825760] ACPI: PCI Interrupt 0000:03:0e.0[A] -> GSI 22 (level, low) ->
> > IRQ 22
> > [ 0.805755] Switched to high resolution mode on CPU 1
> > [ 0.794244] Switched to high resolution mode on CPU 2
> > [ 0.766968] Switched to high resolution mode on CPU 3
> > [ 1.083944] Switched to high resolution mode on CPU 0
> > [ 15.388792] Clocksource tsc unstable (delta = 9373391604 ns)

Doh, this looks like the acpi_pm timer is not working at all.

> > [ 15.714648] Time: acpi_pm clocksource has been installed.
> > ..
> >
> > Booting nohz=off fixes that.
> >
> > Another strange thing is when I try to boot that kernel with
> > clocksource=acpi_pm it just hangs.

Which confirms the above.

> > config is attached.
> >
> > Please let me know if you need more infos / want me to try patches or
> > anything else.
>
> Please post your full dmesg output.

Yes please.

Thanks,
tglx
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