Dhrystone

Dhrystone is a synthetic computer benchmark introduced in 1984 by Reinhold P. Weicker to measure integer performance of processors and compilers. The benchmark consists of a small C program that models a mix of typical systems software operations, including procedures calls, pointer manipulation, record and array handling, and string processing, with an emphasis on integer computation rather than floating-point performance.

The test runs a fixed number of Dhrystone iterations and reports the result as the rate of Dhrystones per second. From this value, a commonly used metric called DMIPS (Dhrystone MIPS) is derived by dividing the Dhrystone rate by a reference constant, historically 1757.0, to estimate a million instructions per second on a reference machine. Dhrystone has undergone several revisions, with Dhrystone 2.x becoming the prevalent version since the 1990s.

Dhrystone results have been widely used to compare CPUs, microcontrollers, compilers, and embedded systems, and have appeared in various benchmarking suites and vendor performance reports. However, the benchmark is criticized for not reflecting real-world workloads, being sensitive to compiler optimizations, language choices, and runtime environments, and for lacking cross-language equivalence. As a result, contemporary benchmarking often favor more representative suites such as SPEC CPU and CoreMark for embedded contexts. The Dhrystone source code is publicly available and has been ported to many languages beyond C, contributing to its broad historical adoption.