Stress-ng

Stress-ng is a system stress tool that hammers CPU, memory, I/O, kernel interfaces, and more so you can shake out hardware faults, thermal issues, and kernel bugs. This is not meant to function as a precise benchmark.

Important

stress-ng is best used with monitoring tools to observe system behavior under stress. It is highly recommended to utilize top, htop, temps (sensors), and logs (dmesg -w) while running stress-ng. If you prefer a GUI, you may utilize hardinfo or gnome-system-monitor.

Information

stress-ng is one of the preinstalled packages for our r/Techsupport Rescue Media. If you are using this live image, you can skip the installation section.

How to install stress-ng

Refer below for installation instructions if you are not using our live image or want to install it on your own system.
Installing stress-ng

Debian / Ubuntu / Linux Mint:
Terminal window
sudo apt update && sudo apt install stress-ng
Fedora / RHEL / CentOS / AlmaLinux:
Terminal window
sudo dnf install stress-ng
Arch / Manjaro / CachyOS:
Terminal window
sudo pacman -Syu stress-ng

Common tests to run

Use the following if you are not aware of how to use stress-ng, or just want to run some common tests.

Full CPU and memory stress test (1 hour): Stresses all CPU cores and allocates 60% of RAM for memory stress.

sudo stress-ng --cpu 0 --vm 1 --vm-bytes 60% --timeout 1h --metrics-brief

Network stress test (10 min): Stresses TCP and UDP sockets.

sudo stress-ng --sock 4 --udp 4 --timeout 10m --metrics-brief

Scheduler and context switching (10 min): Stresses process scheduling, voluntary yields, and CPU affinity.

sudo stress-ng --class os --seq 1 --timeout 10m --metrics-brief

Inter-process communication (IPC) (10 min): Stresses pipes, message queues, and semaphores.

sudo stress-ng --pipe 8 --msg 4 --sem 4 --timeout 10m --metrics-brief

Cache stress test (10 min): Stresses all CPU cache levels (L1, L2, LLC).

sudo stress-ng --cache 0 --l1cache 0 --llc-cache 0 --timeout 10m --metrics-brief

Filesystem I/O stress test (10 min): Stresses filesystem I/O using sequential read/write operations.

cd /tmp  # or a dir with >50GB free space
sudo stress-ng --class filesystem --seq 1 --timeout 10m --metrics-brief

Comprehensive system stress test (30 min): Stresses a wide range of system components including CPU, memory, I/O, and kernel interfaces. Comprehensive but may be intensive. Monitor system temperature very closely.

sudo stress-ng --class all --seq 1 --timeout 30m --metrics-brief

WARNING

Always monitor system temperatures and stability during these tests to avoid overheating or hardware stress.

Usage guidelines

This is a guide for making your own custom tests. When running stress-ng, you can specify the type of stress test, the number of workers, and the duration. Here are some common examples:

Run a single CPU stressor on all cores for 60s:
Terminal window
```
stress-ng --cpu 0 --timeout 60s --metrics-brief
```

RAM/virtual memory stress, all cores, 2 minutes:

stress-ng --vm 0 --vm-bytes 80% --timeout 2m --metrics-brief

Filesystem I/O stress (temp files in current directory) for 2 minutes:
Terminal window
```
stress-ng --hdd 4 --timeout 2m --metrics-brief
```

Run several types together:

stress-ng --cpu 4 --vm 2 --io 2 --timeout 2m --metrics-brief

The most common flags you may use while running stress-ng are:

--timeout 60s or -t 60s: how long to run that test.
--metrics-brief: show summary stats at the end.
--verify: add basic correctness checks where supported (slower but safer).
--class cpu --seq 1 -t 30s: run all CPU-related stressors one after another.

An example of a “full system” stress test:

stress-ng --class cpu --class vm --class io --seq 1 --timeout 30s --metrics-brief

This walks through CPU, memory, and I/O stressors sequentially, 30 seconds each.

More details on stressors

Stress-ng calls each test a “stressor”. There are 300+; you won’t memorize them, so you discover and filter them:

List all stressors:
Terminal window
```
stress-ng --stressors
```
List stressors that support —verify:
Terminal window
```
stress-ng --verifiable
```
Show stressors by class, e.g. all CPU-related:
Terminal window
```
stress-ng --class cpu\?
```
or all memory-related:
Terminal window
```
stress-ng --class vm\?
```

Each stressor has its own --name and optional --name-ops etc. A few common families.

CPU / compute: --cpu, --matrix, --bitops, --crc32, --zlib, vector/math variants.
Memory / VM: --vm, --bigheap, --brk, --mmap, --stack, cache-related tests.
Filesystem / I/O: --hdd, --aio, --aiol, --dir, --dentry, --lockf, many fs-specific tests.
Scheduler / OS: --switch, --yield, --futex, --timer, --signal, --pipe, --affinity.
Network: --sock, --udp, --tcp, --dccp, etc.
“Pathological” (can hang a box): enabled only if you add --pathological, e.g. --bind-mount, --smi, --cpu-online.

To see the extra functions and options for a specific stressor, run:

man stress-ng
# /vm-  (search for a specific stressor like vm, hdd, matrix, etc.)

The man page sections list every stressor (--access, --acl, --affinity, --aio, --vm, --bigheap, …) with a short explanation and available -ops and tuning options.

For a full list of stressors and options, refer to the official stress-ng documentation or run stress-ng --help in the terminal.