Original distribution site : https://github.com/shibatch/cputemp
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.
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Check out the source code from our GitHub repository :
git clone https://github.com/shibatch/cputemp -
Run make :
cd cputemp && make
cputemp <sensor ID> <target temperature in celcius> <interval in second> [verbose]
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. For example, you may
need to add amd_pstate=passive to the kernel parameters to use
this tool with AMD CPUs.
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 <sensor ID> <target temperature in celcius> <interval in second> [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.
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.
Copyright Naoki Shibata 2024.