Ubuntu – Ubuntu 13.04 CPU frequency scaling ‘stuck’ on lowest frequency

cpufreqperformancescaling

I've just installed Ubuntu 13.04 on my MacBook Air, after toying around for awhile the machine felt really slow, so I checked out the CPU frequency. cpufreq-info, it reports 800MHz on all 4 cores (which is the lowest setting). The governor is set to ondemand. Now when I put some load on the system (running a small script that hashes stuff four times) the machine grinds to a hold, but cpufreq-info is still reporting 800MHz. I can manually set the frequency to 2GHz, which solves the performance problem, but will cost me my battery.

This is the output of cpufreq-info:

cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 1 2 3
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 10.0 us.
  hardware limits: 800 MHz - 2.00 GHz
  available frequency steps: 2.00 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz, 900 MHz, 800 MHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 800 MHz and 2.00 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
  cpufreq stats: 2.00 GHz:5,75%, 2.00 GHz:0,47%, 1.90 GHz:0,00%, 1.80 GHz:0,01%, 1.70 GHz:0,01%, 1.60 GHz:0,01%, 1.50 GHz:0,01%, 1.40 GHz:0,01%, 1.30 GHz:0,01%, 1.20 GHz:0,02%, 1.10 GHz:0,01%, 1000 MHz:0,02%, 900 MHz:0,02%, 800 MHz:93,67%  (1388)
analyzing CPU 1:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 1 2 3
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 10.0 us.
  hardware limits: 800 MHz - 2.00 GHz
  available frequency steps: 2.00 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz, 900 MHz, 800 MHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 800 MHz and 2.00 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
  cpufreq stats: 2.00 GHz:3,17%, 2.00 GHz:0,01%, 1.90 GHz:0,01%, 1.80 GHz:0,00%, 1.70 GHz:0,00%, 1.60 GHz:0,01%, 1.50 GHz:0,01%, 1.40 GHz:0,01%, 1.30 GHz:0,01%, 1.20 GHz:0,01%, 1.10 GHz:0,01%, 1000 MHz:0,02%, 900 MHz:0,02%, 800 MHz:96,71%  (1433)
analyzing CPU 2:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 1 2 3
  CPUs which need to have their frequency coordinated by software: 2
  maximum transition latency: 10.0 us.
  hardware limits: 800 MHz - 2.00 GHz
  available frequency steps: 2.00 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz, 900 MHz, 800 MHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 800 MHz and 2.00 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
  cpufreq stats: 2.00 GHz:2,69%, 2.00 GHz:0,00%, 1.90 GHz:0,01%, 1.80 GHz:0,01%, 1.70 GHz:0,01%, 1.60 GHz:0,02%, 1.50 GHz:0,01%, 1.40 GHz:0,01%, 1.30 GHz:0,02%, 1.20 GHz:0,02%, 1.10 GHz:0,01%, 1000 MHz:0,02%, 900 MHz:0,02%, 800 MHz:97,16%  (1194)
analyzing CPU 3:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 1 2 3
  CPUs which need to have their frequency coordinated by software: 3
  maximum transition latency: 10.0 us.
  hardware limits: 800 MHz - 2.00 GHz
  available frequency steps: 2.00 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz, 900 MHz, 800 MHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 800 MHz and 2.00 GHz.
                  The governor "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
  cpufreq stats: 2.00 GHz:3,07%, 2.00 GHz:0,02%, 1.90 GHz:0,01%, 1.80 GHz:0,00%, 1.70 GHz:0,01%, 1.60 GHz:0,01%, 1.50 GHz:0,01%, 1.40 GHz:0,01%, 1.30 GHz:0,01%, 1.20 GHz:0,01%, 1.10 GHz:0,03%, 1000 MHz:0,03%, 900 MHz:0,01%, 800 MHz:96,77%  (1004)

Best Answer

I had the same issue on latest version of Mint, setting the scaling to conservative seemed to be the closest to how ondemand used to work.

Then I found out what the problem was, the up_threshold was way too high, it was set to 95% load, now this is fine for continued loads, but in most cases there is a small burst of CPU activity, and you want the CPU to scale to 100% speed much faster. I resolved this by setting th up_threshold lower (75 seems to do OK in my case). You change it by echo'ing the desired value to /sys/devices/system/cpu/cpufreq/ondemand/up_threshold.