Raspberry Pi CPU temperature and throttling test script

pi-cpu-stress.sh

#!/bin/bash
# Raspberry Pi stress CPU temperature measurement script.
#
# Download this script (e.g. with wget) and give it execute permissions (chmod +x).
# Then run it with ./pi-cpu-stress.sh

# Variables.
test_run=1
test_results_file="${HOME}/cpu_temp_$test_run.log"
stress_length="10m"

# Verify stress-ng is installed.
if ! [ -x "$(command -v stress-ng)" ]; then
  printf "Error: stress-ng not installed.\n"
  printf "To install: sudo apt install -y stress-ng\n" >&2
  exit 1
fi

printf "Logging temperature and throttling data to: $test_results_file\n"

# Start logging temperature data in the background.
while /bin/true; do
  # Print the date (e.g. "Wed 13 Nov 18:24:45 GMT 2019") and a tab.
  date | tr '\n' '\t' >> $test_results_file;

  # Print the temperature (e.g. "39.0") and a tab.
  vcgencmd measure_temp | tr -d "temp=" | tr -d "'C" | tr '\n' '\t' >> $test_results_file;

  # Print the throttle status (e.g. "0x0") and a tab.
  vcgencmd get_throttled | tr -d "throttled=" | tr '\n' '\t' >> $test_results_file;

  # Print the current CPU frequency.
  vcgencmd measure_clock arm | sed 's/^.*=//' >> $test_results_file;
  sleep 5;
done &

# Store the logging pid.
PROC_ID=$!

# Stop the logging loop if script is interrupted or when it ends.
trap "kill $PROC_ID" EXIT

# After 5 minutes, run stress.
printf "Waiting 5 minutes for stable idle temperature...\n"
sleep 300
printf "Beginning $stress_length stress test...\n"
stress-ng -c 4 --timeout $stress_length

# Keep logging for 5 more minutes.
printf "Waiting 5 minutes to return to idle temperature...\n"
sleep 300

printf "Test complete.\n"

@geerlingguy - Nope. I ran

#!/bin/bash
while true 
do
vcgencmd measure_temp | tr -d "temp=" | tr -d "'C" | tr '\n' '\t'
echo temp=$((`cat /sys/class/thermal/thermal_zone0/temp`/1000)).0\'C
sleep 10
done

via SSH and tried various uses of stress-ng and glxgears and the biggest difference I saw was 1.4 C. A curiousity, but I don't think relevant...

Thanks for helping me understand!

Weird! I'm surprised there would be that much of a difference. And now I'm wondering if there are multiple temperature sensors in the SoC :)

I am using following script to record temperature :

from  gpiozero import CPUTemperature
from time import sleep, strftime, time

cpu = CPUTemperature()
count=1200      # 20 minutes
with open("/home/pi/temp_log.csv", "a") as  log:
    while True:
        temp = cpu.temperature
         log.write("{0},{1}".format(strftime("%Y-%m-%d %H:%M:%S"), str(temp)))
         sleep(1)
         count -= 1
         if count == 0:
             break

and using sysbench in a loop:

#!/bin/bash
while true; 
do 
     sysbench --test=cpu --cpu-max-prime=20000 --threads=4 run 
     sleep 0.1
done 

and it works fine.

Question: how did you generated the images from the logging data? Is there any nice script for that?

maybe it can be plot by using matplotlib library.