Once you've chosen an appropriate CPUfreq governor, you can further tune the speed of each CPU using the tunables found in
/sys/devices/system/cpu/[cpu ID]
/cpufreq/
. These tunables are:
-
cpuinfo_min_freq
Shows the CPU's available minimum operating frequency (in KHz). -
cpuinfo_max_freq
Shows the CPU's available maximum operating frequency (in KHz). -
scaling_driver
Shows what CPUfreq driver is used to set the frequency on this CPU. -
scaling_available_governors
Shows the CPUfreq governors available in this kernel. If you wish to use a CPUfreq governor that is not listed in this file, refer to Procedure 3.2, “Enabling a CPUfreq Governor” in Section 3.2.2, “CPUfreq Setup” for instructions on how to do so. -
scaling_governor
Shows what CPUfreq governor is currently in use. To use a different governor, simply useecho
(refer to Procedure 3.2, “Enabling a CPUfreq Governor” in Section 3.2.2, “CPUfreq Setup” for more information).[governor]
/sys/devices/system/cpu/[cpu ID]
/cpufreq/scaling_governor -
cpuinfo_cur_freq
Shows the current speed of the CPU (in KHz). -
scaling_available_frequencies
Lists available frequencies for the CPU, in KHz. -
scaling_min_freq
andscaling_max_freq
Sets the policy limits of the CPU, in KHz. -
affected_cpus
Lists CPUs that require frequency coordination software. -
scaling_setspeed
Used to change the clock speed of the CPU, in KHz. You can only set a speed within the policy limits of the CPU (as perscaling_min_freq
andscaling_max_freq
).
To view the current value of each tunable, use
cat [tunable]
. For example, to view the current speed of cpu0 (in KHz), use:
cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
.
To change the value of each tunable, use
echo [value]
/sys/devices/system/cpu/[cpu ID]
/cpufreq/[tunable]
. For example, to set the minimum clock speed of cpu0 to 360 KHz, use:
echo 360000 /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq