The performance governor for cpufreq doesn't seem to behave as adverti

[mgoldshteyn]

The kernel in use: 3.2.0-23-generic on Ubuntu 12.04LTS

For example, I issue the following command:

sudo cpufreq-set -c 0 -g performance

Then I go to /sys/devices/system/cpu/cpu0/cpufreq and type in the following:

sudo cat cpuinfo_cur_freq

Sometimes I get the max frequency (3600 MHz) when I do this and sometimes I get the min frequency (1600 MHz).

If I do:

cat scaling_governor

The output is performance, showing that the governor is in fact set to performance.

Then, to make it even more weird, if I do:

cpufreq-info

I get:

analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 1 2 3 8 9 10 11
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 10.0 us.
  hardware limits: 1.60 GHz - 3.60 GHz
  available frequency steps: 3.60 GHz, 3.60 GHz, 3.47 GHz, 3.33 GHz, 3.20 GHz, 3.07 GHz, 2.93 GHz, 2.80 GHz, 2.67 GHz, 2.53 GHz, 2.40 GHz, 2.27 GHz, 2.13 GHz, 2.00 GHz, 1.87 GHz, 1.73 GHz, 1.60 GHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 3.60 GHz and 3.60 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 3.60 GHz.
...

If you look at the current policy above, you will notice that it is telling me that the CPU should be pegged at 3.60 GHz. Yet, polling (i.e., displaying) cpuinfo_cur_freq once a second seems to tell a different story.