- fine tune activities on a system.
- monitor operating system kernel interfaces.
- test your Linux hardware components such as CPU, memory, disk devices and many others to observe their performance under stress.
- measure different power consuming loads on a system.
In this guide, we shall look at two important tools, stress and stress-ng for stress testing under your Linux systems.
1. stress – is a workload generator tool designed to subject your system to a configurable measure of CPU, memory, I/O and disk stress.
2. stress-ng – is an updated version of the stress workload generator tool which tests your system for following features:
1. stress – is a workload generator tool designed to subject your system to a configurable measure of CPU, memory, I/O and disk stress.
2. stress-ng – is an updated version of the stress workload generator tool which tests your system for following features:
- CPU compute
- drive stress
- I/O syncs
- Pipe I/O
- cache thrashing
- VM stress
- socket stressing
- process creation and termination
- context switching properties
Though these tools are good for examining your system, they should not just be used by any system user.
Important: It is highly recommended that you use these tools with root user privileges, because they can stress your Linux machine so fast and to avoid certain system errors on poorly designed hardware.
How to Install ‘stress’ Tool in Linux
To install stress tool on Debian and its derivatives such Ubuntu and Mint, run the following command.
$ sudo apt-get install stress
To install stress on a RHEL/CentOS and Fedora Linux, you need to turn on EPEL repository and then type the following yum command to install the same:
# yum install stress
The general syntax for using stress is:
$ sudo stress option argument
# yum install stress
The general syntax for using stress is:
$ sudo stress option argument
Some options that you can use with stress.
1. To examine effect of the command every time you run it, first run the uptime command and note down the load average.
Next, run the stress command to spawn 8 workers spinning on sqrt() with a timeout of 20 seconds. After running stress, again run the uptime command and compare the load average.
2. To spwan 8 workers spinning on sqrt() with a timeout of 30 seconds, showing detailed information about the operation, run this command:
Some of the options that you can use with stress-ng:
As recommended, these tools should be used with superuser privileges as they have certain effects on the system. These tools are good for general System Administration in Linux. I hope this guide was useful and if you have any additional ideas on how to test the health status of your system using these tools or any other tools.
- To spawn N workers spinning on sqrt() function, use the –cpu N option as follows.
- To spawn N workers spinning on sync() function, use the –io N option as follows.
- To spawn N workers spinning on malloc()/free() functions, use the –vm N option.
- To allocate memory per vm worker, use the –vm-bytes N option.
- Instead of freeing and reallocating memory resources, you can redirty memory by using the –vm-keep option.
- Set sleep to N seconds before freeing memory by using the –vm-hang N option.
- To spawn N workers spinning on write()/unlink() functions, use the –hdd N option.
- You can set a timeout after N seconds by using the –timeout N option.
- Set a wait factor of N microseconds before any work starts by using the –backoff N option as follows.
- To show more detailed information when running stress, use the -v option.
- Use –help to view help for using stress or view the manpage.
How Do I use stress on Linux systems?
1. To examine effect of the command every time you run it, first run the uptime command and note down the load average.
Next, run the stress command to spawn 8 workers spinning on sqrt() with a timeout of 20 seconds. After running stress, again run the uptime command and compare the load average.
nilaxan@localhost ~ $ uptime nilaxan@localhost ~ $ sudo stress --cpu 8 --timeout 20 nilaxan@localhost ~ $ uptime
Sample Output
nilaxan@localhost ~ $ uptime 17:20:00 up 7:51, 2 users, load average: 1.91, 2.16, 1.93 [<-- Watch Load Average] nilaxan@localhost ~ $ sudo stress --cpu 8 --timeout 20 stress: info: [17246] dispatching hogs: 8 cpu, 0 io, 0 vm, 0 hdd stress: info: [17246] successful run completed in 21s nilaxan@localhost ~ $ uptime 17:20:24 up 7:51, 2 users, load average: 5.14, 2.88, 2.17 [<-- Watch Load Average]
2. To spwan 8 workers spinning on sqrt() with a timeout of 30 seconds, showing detailed information about the operation, run this command:
nilaxan@localhost ~ $ uptime nilaxan@localhost ~ $ sudo stress --cpu 8 -v --timeout 30s nilaxan@localhost ~ $ uptime
Sample Output
nilaxan@localhost ~ $ uptime 17:27:25 up 7:58, 2 users, load average: 1.40, 1.90, 1.98 [<-- Watch Load Average] nilaxan@localhost ~ $ sudo stress --cpu 8 -v --timeout 30s stress: info: [17353] dispatching hogs: 8 cpu, 0 io, 0 vm, 0 hdd stress: dbug: [17353] using backoff sleep of 24000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 8 [17354] forked stress: dbug: [17353] using backoff sleep of 21000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 7 [17355] forked stress: dbug: [17353] using backoff sleep of 18000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 6 [17356] forked stress: dbug: [17353] using backoff sleep of 15000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 5 [17357] forked stress: dbug: [17353] using backoff sleep of 12000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 4 [17358] forked stress: dbug: [17353] using backoff sleep of 9000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 3 [17359] forked stress: dbug: [17353] using backoff sleep of 6000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 2 [17360] forked stress: dbug: [17353] using backoff sleep of 3000us stress: dbug: [17353] setting timeout to 30s stress: dbug: [17353] --> hogcpu worker 1 [17361] forked stress: dbug: [17353]
nilaxan@localhost ~ $ uptime 17:27:59 up 7:59, 2 users, load average: 5.41, 2.82, 2.28 [<-- Watch Load Average]3. To spwan one worker of malloc() and free() functions with a timeout of 60 seconds, run the following command.
nilaxan@localhost ~ $ uptime nilaxan@localhost ~ $ sudo stress --vm 1 --timeout 60s nilaxan@localhost ~ $ uptime
Sample Output
nilaxan@localhost ~ $ uptime 17:34:07 up 8:05, 2 users, load average: 1.54, 2.04, 2.11 [<-- Watch Load Average] nilaxan@localhost ~ $ sudo stress --vm 1 --timeout 60s stress: info: [17420] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd stress: info: [17420] successful run completed in 60s nilaxan@localhost ~ $ uptime 17:35:20 up 8:06, 2 users, load average: 2.45, 2.24, 2.17 [<-- Watch Load Average]4. To spwan 4 workers spinning on sqrt(), 2 workers spwaning on sync(), 2 workers on malloc()/free(), with a time out of 20 seconds and allocate a memory of 256MB per vm worker, run this command below.
nilaxan@localhost ~ $ uptime nilaxan@localhost ~ $ sudo stress --cpu 4 --io 3 --vm 2 --vm-bytes 256M --timeout 20s nilaxan@localhost ~ $ uptime
Sample Output
nilaxan@localhost ~ $ uptime 17:40:33 up 8:12, 2 users, load average: 1.68, 1.84, 2.02 [<-- Watch Load Average] nilaxan@localhost ~ $ sudo stress --cpu 4 --io 3 --vm 2 --vm-bytes 256M --timeout 20s stress: info: [17501] dispatching hogs: 4 cpu, 3 io, 2 vm, 0 hdd stress: info: [17501] successful run completed in 20s nilaxan@localhost ~ $ uptime 17:40:58 up 8:12, 2 users, load average: 4.63, 2.54, 2.24 [<-- Watch Load Average]
How to Install ‘stress-ng’ Tool in Linux
To install stress-ng, run the following command.$ sudo apt-get install stress-ng [on Debian based systems] # yum install stress-ng [on RedHat based systems]
The general syntax for using `stress-ng` is :
$ sudo stress-ng option argument
Some of the options that you can use with stress-ng:
- To start N instances of each stress test, use the –all N option as follows.
- To start N processes to exercises the CPU by sequentially working through all the different CPU stress testing methods, use the –cpu N option as follows.
- To use a given CPU stress testing method, use –cpu-method option. There are many methods available that you can use, to view the manpage to see all the methods to use.
- To stop CPU stress process after N bogo operations, use the –cpu-ops N option.
- To start N I/O stress testing processes, use the –io N option.
- To stop io stress processes after N bogo operations, use the –io-ops N option.
- To start N vm stress testing processes, use the –vm N option.
- To specify amount of memory per vm process, use –vm-bytes N option.
- To stop vm stress processes after N bogo operations, use –vm-ops N options
- Use the –hdd N option to start N harddisk exercising processes.
- To stop hdd stress processes after N bogo operations, use –hdd-ops N option.
- You can set a timeout after N seconds by using the –timeout N option.
- To generate a summary report after bogo operations, you can use –metrics or –metrics-brief options. The –metrics-brief displays non zero metrics.
- You can also start N processes that will create and remove directories using mkdir and rmdir by using the –dir N option.
- To stop directory operations processes use –dir-ops N options.
- To start N CPU consuming processes that will exercise the present nice levels, include the
- –nice N option. When using this option, every iteration will fork off a child process that runs through all the different nice levels running a busy loop for 0.1 seconds per level and then exits.
- To stop nice loops, use the –nice-ops N option as follows.
- To start N processes that change the file mode bits via chmod(2) and fchmod(2) on the same file, use the –chmod N option. Remember the greater the value for N then the more contention on the file. The stressor will work through all the combination of mode bits that you specify with chmod(2).
- You can stop chmod operations by the –chmod-ops N option.
- You can use the -v option to display more information about ongoing operations.
- Use -h to view help for stress-ng.
How Do I use ‘stress-ng’ in Linux systems?
1. To run 8 CPU stressors with a timeout of 60 seconds and a summary at the end of operation
nilaxan@localhost:~$ uptime nilaxan@localhost:~$ sudo stress-ng --cpu 8 --timeout 60 --metrics-brief nilaxan@localhost:~$ uptime
Sample Output
nilaxan@localhost:~$ uptime 18:15:29 up 12 min, 1 user, load average: 0.00, 0.01, 0.03 [<-- Watch Load Average] nilaxan@localhost:~$ sudo stress-ng --cpu 8 --timeout 60 --metrics-brief stress-ng: info: [1247] dispatching hogs: 8 cpu stress-ng: info: [1247] successful run completed in 60.42s stress-ng: info: [1247] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1247] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1247] cpu 11835 60.32 59.75 0.05 196.20 197.91 nilaxan@localhost:~$ uptime 18:16:47 up 13 min, 1 user, load average: 4.75, 1.47, 0.54 [<-- Watch Load Average]2. To run 4 FFT CPU stressors with a timeout of 2 minutes.
nilaxan@localhost:~$ uptime nilaxan@localhost:~$ sudo stress-ng --cpu 4 --cpu-method fft --timeout 2m nilaxan@localhost:~$ uptime
Sample Output
nilaxan@localhost:~$ uptime 18:25:26 up 22 min, 1 user, load average: 0.00, 0.26, 0.31 [<-- Watch Load Average] nilaxan@localhost:~$ sudo stress-ng --cpu 4 --cpu-method fft --timeout 2m stress-ng: info: [1281] dispatching hogs: 4 cpu stress-ng: info: [1281] successful run completed in 120.01s nilaxan@localhost:~$ uptime 18:27:31 up 24 min, 1 user, load average: 3.21, 1.49, 0.76 [<-- Watch Load Average]3. To run 5 hdd stressors and stop after 100000 bogo operations, run this command.
nilaxan@localhost:~$ uptime nilaxan@localhost:~$ sudo stress-ng --hdd 5 --hdd-ops 100000 nilaxan@localhost:~$ uptime
Sample Output
nilaxan@localhost:~$ uptime 18:29:32 up 26 min, 1 user, load average: 0.43, 1.00, 0.67 [<-- Watch Load Average] nilaxan@localhost:~$ sudo stress-ng --hdd 5 --hdd-ops 100000 stress-ng: info: [1290] defaulting to a 86400 second run per stressor stress-ng: info: [1290] dispatching hogs: 5 hdd stress-ng: info: [1290] successful run completed in 136.16s nilaxan@localhost:~$ uptime 18:31:56 up 29 min, 1 user, load average: 4.24, 2.49, 1.28 [<-- Watch Load Average]4. To run 8 CPU stressors, 4 I/O stressors and 1 virtual memory stressor using 1GB of virtual memory for one minute, run this command below.
nilaxan@localhost:~$ uptime nilaxan@localhost:~$ sudo stress-ng --cpu 4 --io 4 --vm 1 --vm-bytes 1G --timeout 60s --metrics-brief nilaxan@localhost:~$ uptime
Sample Output
nilaxan@localhost:~$ uptime 18:34:18 up 31 min, 1 user, load average: 0.41, 1.56, 1.10 [<-- Watch Load Average] nilaxan@localhost:~$ sudo stress-ng --cpu 4 --io 4 --vm 1 --vm-bytes 1G --timeout 60s --metrics-brief stress-ng: info: [1304] dispatching hogs: 4 cpu, 4 iosync, 1 vm stress-ng: info: [1304] successful run completed in 60.12s stress-ng: info: [1304] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s stress-ng: info: [1304] (secs) (secs) (secs) (real time) (usr+sys time) stress-ng: info: [1304] cpu 1501 60.07 2.67 10.39 24.99 114.93 stress-ng: info: [1304] iosync 381463 60.01 0.00 12.90 6357.10 29570.78 nilaxan@localhost:~$ uptime 18:35:36 up 32 min, 1 user, load average: 4.66, 2.80, 1.59 [<-- Watch Load Average]
Summary
As recommended, these tools should be used with superuser privileges as they have certain effects on the system. These tools are good for general System Administration in Linux. I hope this guide was useful and if you have any additional ideas on how to test the health status of your system using these tools or any other tools.
