stress

Impose CPU, memory, and I/O load

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. Numbers may be suffixed with s, m, h, d, y (time) or B, K, M, G (size). Running excessive stress tests may cause system instability.

HISTORY

stress was written by Amos Waterland as a simple workload generator for POSIX systems. The related stress-ng tool by Colin Ian King provides many more stressor types and metrics.