Comment 93 for bug 22336

This report is quite hard to pin down as these are several different models of computer being reported (effectively there are several bug reports muddled up in one page).

The common trait I found between two of the output is that doing:

  $ cat /proc/acpi/processor/CPU0/throttling

reports "<not supported>". If your laptop doesn't match this, please open a new bug report.

The next question is /why/ we're getting that message; the hardware and BIOS indicate whether throttling (rather than scaling) is possible and this can be controlled via ACPI based on the safe temperature limits provided by the manufacturer of that machine.

Somebody said that they'd had a specific success with Suse 10, in the case where Ubuntu hadn't worked---what does the above file contain when running on SUSE without the problem manifesting itself, does this proc file still indicate "<not supported>"?

Since the last version of Ubuntu, the attempt now is to always use the kernel's built-in "ondemand" scaling where-ever possible rather than running the separate userspace application "powernowd" to make decisions about what scaling speed (not throttling) would be best.

There's a possibility that a mix-up is occuring and 'powernowd' is allowed to remain running in cases where it should not be. This appears to be what Trae McCombs is reporting (stopping 'powernowd' and manually selecting 'ondemand' solves the problem).

Trae: what type of CPU do you have? Could you tell me with the output of running 'lsmod' whether 'p4clockmod' is in use, or another CPU scaling module?