stress

TLDR

Spawn 4 workers to stress test CPU

$ stress -c 4

Spawn 2 workers to stress test IO with timeout

$ stress -i 2 -t 5

Spawn 2 workers to stress test memory

$ stress -m 2 --vm-bytes 256M

Spawn 2 workers to stress test disk

$ stress -d 2 --hdd-bytes 1GB

Run with verbose output

$ stress -v -c 2

SYNOPSIS

stress [-c N] [-i N] [-m N] [-d N] [-t seconds] [OPTIONS]

stress imposes a configurable amount of CPU, memory, I/O, or disk stress on a POSIX-compliant operating system and reports any errors it detects. It is useful for evaluating system scalability, performance characteristics, and exposing bugs that manifest under heavy load conditions.

PARAMETERS

-c, --cpu N

Spawn N workers calculating square roots

-i, --io N

Spawn N workers calling sync()

-m, --vm N

Spawn N workers allocating and freeing memory

--vm-bytes B

Allocate B bytes per vm worker (default: 256MB)

--vm-stride B

Touch bytes at B-byte intervals (default: 4096)

--vm-hang N

Sleep N seconds before freeing memory

--vm-keep

Redirty memory instead of reallocating

-d, --hdd N

Spawn N workers writing and unlinking files

--hdd-bytes B

Write B bytes per hdd worker (default: 1GB)

-t, --timeout N

Terminate after N seconds

--backoff N

Wait N microseconds before starting work

-v, --verbose

Enable verbose output

-q, --quiet

Suppress non-error messages

-n, --dry-run

Display actions without executing them

CAVEATS

This tool is explicitly not a benchmarking tool. Values support time suffixes (s, m, h, d, y) and size suffixes (B, K, M, G). Running excessive stress tests may cause system instability.

HISTORY

stress was designed to test system stability under load conditions. The related stress-ng tool provides more stress test options and metrics.