Change cpu scaling governor in Linux

There are following modes can be choose from:

• performance keeps the CPU at the highest possible frequency
• powersave keeps the CPU at the lowest possible frequency
• userspace exports the available frequency information to the user level (through the /sys file system) and permits user-space control of the CPU frequency
• ondemand scales the CPU frequencies according to the CPU usage (like does the userspace frequency scaling daemons, but in kernel)
• conservative acts like the ondemand but increases frequency step by step

Mine defaults to userspace, to change to powersave mode:

echo "powersave" | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor