ThinkPad T61P Speed Problems

by Miguel de Icaza

I recently upgraded to a ThinkPad T61p. I did not reinstally my OS, but instead just moved the old hard drive into the new machine.

The new machine is supposed to run at 2.4Ghz when plugged to the AC power, but it keeps going down to 1.2Ghz when am trying to get some work done (start a build: cpu speed goes down; Start firefox, cpu speed goes down). When am idling, the CPU speed will happily go back to 2.4Ghz. It can get as bad as 800Mhz, and in fact, it tends to boot in that mode at 800Mhz so booting takes forever.

The machine is cool, unlike the last laptop it does not feel warm at all (perhaps because it never performs better than a PC/XT).

I have Googled and Googled and various people seem to be having this problem across some other machines and Linux distributions, but there does not seem to be any solution posted. This is also not a new problem.

gnome-power-manager shows that the speed policy is "Always Maximum Speed":

This is what cpufreq-info shows:

I have tried:

  • powersave -f, it sometimes makes the machine go to 2.4Ghz, but it will happily go back to 1.2 a few seconds later.
  • Setting the minimal frequency in /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq by writing 2401000 to it. This sometimes works, but sometimes I get:
    		root# echo 2401000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq 
    		sh: echo: write error: Invalid argument
  • Calling: cpufreq-set -c 0 -d 2401000 -u 2401000 -g userspace this again works sometimes but when the CPU insists on sticking to 1.2Ghz it will just produce an error.
  • Variants on cpufreq-set's governor: I tried userspace, and performance. They both seem to fail sometimes, and work sometimes. When they work, the processor speeds only stays for a few seconds before it goes back to slow speed.
  • Tried disabling the speed stepping support in the BIOS. Although /proc/cpuinfo then reports that the CPU is running at 2.4Ghz, regular benchmark programs show that the machine is actually running at 1.2Ghz (building mcs goes from 2.7 seconds to 4.7).
  • Tried killing powesaved, gnome-power-manager to make sure they wre not interfering, they still do not work.

If you got some ideas, drop me an email, I will post any solutions

Posted on 13 Feb 2008