Kernel clock issue "Clocksource tsc unstable"

Rashkae ubuntu at
Sat Feb 28 03:48:37 UTC 2009

NoOp wrote:

> But shouldn't it switch automatically to acpi_pm if tsc is not stable?[1]
> For instance, on the Thinkpad A21M that I receive the dmesg of:
> Clocksource tsc unstable (delta = -87685142 ns)
> I see in BIOS that the sytstem date is OK, but the actual system time is
> 03:03:24 (UTC) (note it's showing the proper time in Ubuntu) - hence the
> 'Clocksource tsc unstable' msg. If I actually set it to that time
> (Local) in BIOS and then reboot & check dmesg again, I now see:
> Clocksource tsc unstable (delta = -1984279121 ns)
> Current clocksource on that machine is acpi_pm with no mods to
> menu.list. It's a fairly new install (hardy) so something in the
> kernel/boot has decided on it's own to not use tsc.
> Anyway... It's all still a mystery to me :-)

In any case, as I said, this is all deep magic that is not meant to be
fiddled with by mere mortals,, I only bring it up because someone was
having severe problems, and I thought it might help narrow down the
issue by taking known problematic tsc out of the picture, since a tsc
unstable error was the only clue to the system lock up.

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