How to create a CPU spike with a bash command

Question

I want to create a near 100% load on a Linux machine. It\'s quad core system and I want all cores going full speed. Ideally, the CPU load would last a designated amount of

Answer 1

I went through the Internet to find something like it and found this very handy cpu hammer script.

#!/bin/sh

# unixfoo.blogspot.com

if [ $1 ]; then
    NUM_PROC=$1
else
    NUM_PROC=10
fi

for i in `seq 0 $((NUM_PROC-1))`; do
    awk 'BEGIN {for(i=0;i<10000;i++)for(j=0;j<10000;j++);}' &
done

Answer 2

:(){ :|:& };:

This fork bomb will cause havoc to the CPU and will likely crash your computer.

Answer 3

Using examples mentioned here, but also help from IRC, I developed my own CPU stress testing script. It uses a subshell per thread and the endless loop technique. You can also specify the number of threads and the amount of time interactively.

#!/bin/bash
# Simple CPU stress test script

# Read the user's input
echo -n "Number of CPU threads to test: "
read cpu_threads
echo -n "Duration of the test (in seconds): "
read cpu_time

# Run an endless loop on each thread to generate 100% CPU
echo -e "\E[32mStressing ${cpu_threads} threads for ${cpu_time} seconds...\E[37m"
for i in $(seq ${cpu_threads}); do
    let thread=${i}-1
    (taskset -cp ${thread} $BASHPID; while true; do true; done) &
done

# Once the time runs out, kill all of the loops
sleep ${cpu_time}
echo -e "\E[32mStressing complete.\E[37m"
kill 0

Answer 4

I think this one is more simpler. Open Terminal and type the following and press Enter.

yes > /dev/null &

To fully utilize modern CPUs, one line is not enough, you may need to repeat the command to exhaust all the CPU power.

To end all of this, simply put

killall yes

The idea was originally found here, although it was intended for Mac users, but this should work for *nix as well.

Answer 5

An infinite loop is the idea I also had. A freaky-looking one is:

while :; do :; done

(: is the same as true, does nothing and exits with zero)

You can call that in a subshell and run in the background. Doing that $num_cores times should be enough. After sleeping the desired time you can kill them all, you get the PIDs with jobs -p (hint: xargs)

Answer 6

#!/bin/bash
while [ 1 ]
do
        #Your code goes here
done