how do I know if the BIOS or the OS is throttling my CPU? (Linux)

Question

I'm using Ubuntu Linux 18.04. I've been sold a second hand Dell Precision M6700 Laptop with an under-powered power adaptor.

Apparently the BIOS is able to recognise this condition and I read somewhere that it will apply an extreme throttle to the CPU.

I wonder please how can I check if the throttle is on or not.

Many thanks :)

Answer 1

To find the current CPU speed on all cores:

cat /proc/cpuinfo | grep "cpu MHz"

You can also check /sys/devices/system/cpu/cpufreq/policy{N}/scaling_max_freq and see if it is consistent with your CPU model. Other files in the same directories may be of interest (energy_performance_preference)