thermal_throttle.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

static int limit_temp_mc = 65000;
static long long power_step_down_uw = -1000000;
static long long power_step_up_uw = 200000;
static long long power_limit_stock = 50000000;
static long long power_limit_min = 15000000;

static long long power_limit_uw = 50000000;

void set_power_limit_uw(long long uw)
{
	char buf[255];
	snprintf(buf, sizeof buf, "%lld", uw);

	FILE* fh = fopen("/sys/devices/virtual/powercap/intel-rapl/intel-rapl:0/constraint_0_power_limit_uw", "wt");

	if (fh)
	{
		fputs(buf, fh);
		fclose(fh);
	}
}

int read_number(const char* filename)
{
	char buf[32];
	FILE* hwmon = fopen(filename, "r");

	int num = -1;

	if (hwmon != NULL && fgets(buf, 32, hwmon))
	{
		sscanf(buf, "%d", &num);
		fclose(hwmon);
	}

	return num;
}

int main()
{
	char buf[255];

	set_power_limit_uw(power_limit_uw);

	while (1)
	{
		limit_temp_mc = read_number("/tmp/cpu_temp") * 1000;

		if (limit_temp_mc <= 0)
			limit_temp_mc = 65000;
		else if (limit_temp_mc >= 70000)
			limit_temp_mc = 70000;
		else if (limit_temp_mc < 30000)
			limit_temp_mc = 30000;

		FILE* hwmon = fopen("/sys/class/hwmon/hwmon2/temp1_input", "r");

		int cpu_temp_mc = -1;

		if (hwmon != NULL && fgets(buf, 255, hwmon))
		{
			sscanf(buf, "%d", &cpu_temp_mc);
		}

		if (hwmon != NULL) fclose(hwmon);

		if (cpu_temp_mc == -1 || cpu_temp_mc > limit_temp_mc)
		{
			power_limit_uw += power_step_down_uw * ((cpu_temp_mc - limit_temp_mc + 999) / 1000);

			if (power_limit_uw < power_limit_min)
				power_limit_uw = power_limit_min;

			set_power_limit_uw(power_limit_uw);
		}
		else if (cpu_temp_mc < limit_temp_mc && power_limit_uw < power_limit_stock)
		{
			power_limit_uw += power_step_up_uw * ((limit_temp_mc - cpu_temp_mc + 999) / 1000);

			if (power_limit_uw > power_limit_stock)
				power_limit_uw = power_limit_stock;

			set_power_limit_uw(power_limit_uw);
		}

		usleep(1000000);
	}

	return 0;
}