set_cpu_frequency.py

import os
import sys
import multiprocessing
import subprocess

class CPUFreq:
	@classmethod
	def set_cpu_frequency(cls, frequency : int = None):
		if (os.geteuid() != 0):
			print("root permission is required to run this script", file=sys.stderr)
			exit()

		driver = cls.check_scaling_driver()
		if driver == "intel_cpufreq":
			print("Intel cpufreq driver is active, setting governor to userspace")
			cls.set_scaling_governor("userspace")

			if frequency is None:
				print("Error: frequency required for userspace governor, exiting..", file=sys.stderr)
				exit()

			if frequency < 0 or frequency % 100 != 0:
				print("frequency must be a positive multiple of 100MHz", file=sys.stderr)
				exit()

			frequency = frequency * 1000
			min_freq = cls.get_minimum_frequency(0)
			max_freq = cls.get_maximum_frequency(0)
			if frequency < min_freq:
				print(f"frequency {frequency//1000}MHz is below minimum "
				      f"{min_freq//1000}MHz, setting to minimum", file=sys.stderr)
				frequency = min_freq
			if frequency > max_freq:
				print(f"frequency {frequency//1000}MHz is above maximum "
				      f"{max_freq//1000}MHz, setting to maximum", file=sys.stderr)
				frequency = max_freq

			print(f"Setting CPU frequency to {frequency//1000}MHz")
			for cpu in range(multiprocessing.cpu_count()):
				os.system(f"echo {frequency} > {cls.scaling_setspeed_path(cpu)}")
		elif driver == "intel_pstate":
			print("Intel P-State driver is active")
			if frequency is not None:
				print(f"Warning: {driver} doesn't allow setting specific frequency, "
					"setting to performance mode instead", file=sys.stderr)
			cls.set_scaling_governor("performance")
		else:
			print(f"Unknown/Unsupported scaling driver: `{driver}`, unable to set governor", file=sys.stderr)
			exit()

	@classmethod
	def set_scaling_governor(cls, strategy : str):
		for cpu in range(multiprocessing.cpu_count()):
			cls.check_governors(cpu, strategy)
			os.system(f"echo {strategy} > {cls.scaling_governor_path(cpu)}")

	@classmethod
	def check_scaling_driver(cls):
		path = "/sys/devices/system/cpu/cpufreq/policy0/scaling_driver"
		return cls.cat_path(path).strip()

	@classmethod
	def check_governors(cls, cpu : int, strategy : str):
		if not os.path.isfile(cls.available_governors_path(cpu)) or \
		   not os.path.isfile(cls.scaling_governor_path(cpu)):
			print("WARN: Power scaling settings not properly configured (ie: cpufreq directory DNE)")
			exit()

		available_governors = cls.cat_path(cls.available_governors_path(cpu)).strip().split()
		if strategy not in available_governors:
			print(f"Error: {strategy} is not a valid governor for cpu{cpu}", file=sys.stderr)
			print(f"Available governors: {available_governors}", file=sys.stderr)
			exit()

	@classmethod
	def get_minimum_frequency(cls, cpu : int):
		path = f"/sys/devices/system/cpu/cpu{cpu}/cpufreq/scaling_min_freq"
		min_freq = cls.cat_path(path)
		return int(min_freq.strip())

	@classmethod
	def get_maximum_frequency(cls, cpu : int):
		path = f"/sys/devices/system/cpu/cpu{cpu}/cpufreq/scaling_max_freq"
		max_freq = cls.cat_path(path)
		return int(max_freq.strip())

	@classmethod
	def scaling_setspeed_path(cls, cpu : int):
		return f"/sys/devices/system/cpu/cpu{cpu}/cpufreq/scaling_setspeed"

	@classmethod
	def scaling_governor_path(cls, cpu : int):
		return f"/sys/devices/system/cpu/cpu{cpu}/cpufreq/scaling_governor"

	@classmethod
	def available_governors_path(cls, cpu : int):
		return f"/sys/devices/system/cpu/cpu{cpu}/cpufreq/scaling_available_governors"

	@classmethod
	def cat_path(cls, path : str):
		if not os.path.isfile(path):
			print(f"Error: {path} does not exist", file=sys.stderr)
			exit()

		cmd = f"cat {path}"
		process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
		stdout, stderr = process.communicate()
		if process.returncode != 0:
			print(f"Error: {stderr}", file=sys.stderr)
			return None

		return stdout


if __name__ == "__main__":
	if len(sys.argv) > 1:
		try:
			frequency = int(sys.argv[1])
		except ValueError:
			print("Invalid frequency value, must be an integer", file=sys.stderr)
			exit()
	else:
		frequency = None

	CPUFreq.set_cpu_frequency(frequency)