STREAM

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What STREAM is

STREAM is a free synthetic benchmark that measures sustainable memory bandwidth and computation rates for simple vector kernels. It repeatedly runs Copy, Scale, Add, and Triad using datasets intended to exceed available cache, helping results reflect large vector-style workloads. C and Fortran source code is available, and the standard versions include OpenMP directives; an MPI version supports cluster runs. STREAM supports Linux, macOS, and Windows, while its operating-system list also mentions DOS and Power Mac. Users can create custom profiles, automate runs from the command line, and export comma-delimited raw data files. The site provides a comparison database and tables covering bandwidth, machine balance, and equivalent MFLOPS. Standard results require 64-bit data types on production hardware and exclude simulated or significantly modified code. A tuned-results set permits code changes, including assembly language. Published standard results must follow the run rules, and modified runs must be labeled.

Who it suits

It suits developers, researchers, and administrators comparing memory bandwidth or vector-kernel performance across systems and clusters.

What it does well

Free benchmark with source code
C, Fortran, OpenMP, and MPI options
Custom profiles and command-line automation
Published comparison database
Raw CSV-style export

What to know first

Precompiled binaries described as obsolete
Results require run-rule compliance
No warranty is expressed or implied

Verdict

STREAM is a focused benchmark for sustained memory bandwidth and simple vector computations. Its source-based workflow, automation, and published result rules support repeatable comparisons when users follow the stated standards.

Facts from STREAM's own pages

Cache-sized data: STREAM is designed to use datasets much larger than available cache so results better reflect performance for large vector-style applications. · cs.virginia.edu, 5 Oct 2026
CLI or automation: Yes · cs.virginia.edu, 22 Sept 2026
Comparison database: Yes · cs.virginia.edu, 22 Sept 2026
Custom test profiles: Yes · cs.virginia.edu, 22 Sept 2026
Free plan: Yes · cs.virginia.edu, 22 Sept 2026
Intended use: It is designed to use datasets much larger than available cache, to make results more indicative of large vector style applications. · cs.virginia.edu, 5 Oct 2026
Kernels: The benchmark repeats four kernels: Copy, Scale, Add, and Triad. · cs.virginia.edu, 5 Oct 2026
Maintainer: The FAQ identifies John McCalpin as STREAM's creator and maintainer. · cs.virginia.edu, 5 Oct 2026
Operating systems: Linux; Windows; DOS; Power Mac · cs.virginia.edu, 22 Sept 2026
Parallel runs: The standard C and Fortran code includes OpenMP directives, and an MPI version is available for cluster runs. · cs.virginia.edu, 5 Oct 2026
Project hosting: The site says STREAM is hosted at the University of Virginia in Charlottesville, Virginia. · cs.virginia.edu, 5 Oct 2026
Project status: The site describes STREAM as an independent academic project hosted at the University of Virginia. · cs.virginia.edu, 5 Oct 2026
Published results: Results labeled as standard STREAM benchmark results must conform to the STREAM Run Rules; modified or nonconforming runs must be clearly labeled. · cs.virginia.edu, 5 Oct 2026
Publishing results: Published results called “STREAM benchmark results” must conform to the run rules, and modified-code results must be clearly labelled. · cs.virginia.edu, 5 Oct 2026
Purpose: STREAM is a synthetic benchmark that measures sustainable memory bandwidth and computation rates for simple vector kernels. · cs.virginia.edu, 5 Oct 2026
Result export formats: comma-delimited raw data files · cs.virginia.edu, 22 Sept 2026
Results database: The site publishes benchmark results in tables covering bandwidth, machine balance, and equivalent MFLOPS. · cs.virginia.edu, 5 Oct 2026
Source code: The site recommends compiling the benchmark from its C or Fortran source code. · cs.virginia.edu, 5 Oct 2026
Source languages: The maker recommends compiling the source code, which is available in C or Fortran. · cs.virginia.edu, 5 Oct 2026
Standards: The standard results set uses C or Fortran versions with 64-bit data types on production hardware and excludes simulated results and significantly modified code. · cs.virginia.edu, 5 Oct 2026
Tuned results: The tuned results set allows code modifications, including assembly language, while requiring 64-bit data types on production hardware. · cs.virginia.edu, 5 Oct 2026
Use and redistribution: The run rules permit use and redistribution, and permit modification for personal use including commercial use, subject to publication restrictions. · cs.virginia.edu, 5 Oct 2026
Warranty: The run rules state that no warranty is expressed or implied. · cs.virginia.edu, 5 Oct 2026
Windows and Linux binaries: The FAQ lists precompiled binaries for Windows and Linux but describes the available binaries as obsolete and recommends compiling the source. · cs.virginia.edu, 5 Oct 2026

Where STREAM stands on Freedom251

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