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https://github.com/shibatch/cputemp

Tool for controlling clock frequency to keep CPU below specified temperature
https://github.com/shibatch/cputemp

cpu-frequency cpu-frequency-scaling cpu-monitoring cpu-throttle cpufreq temperature-controller temperature-monitoring temperature-sensor

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Tool for controlling clock frequency to keep CPU below specified temperature

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README 

        
## cputemp - A simple tool to keep CPU below specified temperature on Linux computer



Original distribution site : https://github.com/shibatch/cputemp



### Introduction



Some modern CPUs can reach temperatures near 100 degrees Celsius even

when used at stock clock frequency without overclocking. However, it

is indeed scary to use a CPU regularly near Tjunction. If possible, I

would like to avoid the CPU fan to hum and the high temperature

exhaust to spout out from the back of my PC.



There are various theories, but it is said that the safe temperature

for regular use of CPUs is about 80 degrees Celsius. If we want to use

our CPUs below this temperature, the clock frequency must be

lowered. But how much the frequency should be set to keep the

temperature below 80 degrees depends on the ambient temperature. If a

CPU has many cores, the CPU temperature depends not only on the clock

frequency but also on the usage of each core. More to the point, even

when all cores are running at 100% load, the CPU temperature can vary

considerably depending on what kind of code is being executed. Since

the CPU cooler is a piece of metal and has a good amount of heat

capacity, the CPU temperature will not exceed 80 degrees if the time

of running at a relatively high clock frequency is short.



This tool monitors CPU temperature and dynamically changes the clock

frequency to keep the CPU below the specified temperature on a Linux

computer. This is basically a simple alternative to thermald, but this

tool controls the CPU temperature more aggressively than thermald.



### How to build



1. Check out the source code from our GitHub repository :

`git clone https://github.com/shibatch/cputemp`



2. Run make :

`cd cputemp && make`



### Synopsis



`cputemp    [verbose]`



### Description



This tool monitors temperature obtained by the sensor specified by

sensor ID every specified interval, and control the CPU clock

frequency so that the temperature is kept below the specified target

temperature.



The CPU clock frequency is controlled by changing the value of

`/sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq`.  This means

that this tool requires the cpufreq driver to honor the value of

scaling_max_freq in order to work correctly. Some CPUs need kernel

parameters to be set appropriately for this.



To use this tool, you first need to check which sensor gives the CPU

temperature. You can see the list of available sensor IDs by executing

the command without an argument, like the following.



```

$ ./cputemp

This program controls the CPU frequency to make its temperature close to the target

Usage : ./cputemp    [verbose]



https://github.com/shibatch



Sensor IDs : nvme (42.9 C), k10temp (55.9 C), mt7921_phy0 (52 C), amdgpu (54 C),

$

```



In the above example, there are 4 sensors, and the sensor ID that

gives the CPU temperature is k10temp.



Then, you can specify this sensor ID and start the command as

root. You can see the verbose output of how the temperature is

controlled by giving the 4th argument.



```

$ su

Password:

# ./cputemp k10temp 80 1 -

Sensor file name : /sys/class/hwmon/hwmon1/temp1_input

Max freq : 5881 MHz

Min freq : 400 MHz

CPU freq =   557MHz, enforced freq =  5881MHz, CPU temp = 56.1, target temp = 80

CPU freq =   619MHz, enforced freq =  5881MHz, CPU temp = 56.1, target temp = 80

CPU freq =   674MHz, enforced freq =  5881MHz, CPU temp = 56, target temp = 80

^C

#

```



You should be able to observe that the CPU frequency is lowered and

the CPU temperature is kept below the specified temperature by

executing some task in another tty. If you are satisfied with the

results, you can copy the executable to /usr/local/bin and start it in

/etc/rc.local.



### License



The software is distributed under the Zero-Clause BSD, which means

that this software is in public domain.



The fact that this software is released under an open source license

only means that you can use the current version of the software for

free. If you want this software to be maintained, you need to

financially support the project. Please see

[CODE_OF_CONDUCT.md](https://github.com/shibatch/nofreelunch?tab=coc-ov-file).



Copyright Naoki Shibata 2024.