1. Performance Metrics of Processors

There are many performance metrics used to evaluate CPUs, and the values obtained from different testing standards may vary based on the focus of the performance being tested. Below are two classic testing standards widely used in the embedded industry.

1.1 Dhrystone Standard

Dhrystone is a benchmark testing program proposed by Reinhold P. Weicker in 1984, primarily aimed at testing the performance of integer and logical operations of processors.

The Dhrystone program was initially released in Ada language, later Rick Richardson developed a C language version for Unix, which successfully promoted the widespread application of Dhrystone. The latest version of the Dhrystone program was updated in 1988 to Version 2.1.

The testing method of the Dhrystone standard is very simple: it measures how many times the Dhrystone program runs in a unit of time, with the metric unit being DMIPS/MHz. MIPS stands for Million Instructions Per Second, which is the number of millions of machine language instructions processed per second. The D in DMIPS stands for Dhrystone, indicating the MIPS under the Dhrystone standard testing method.

1.2 CoreMark Standard

CoreMark is a benchmark testing program proposed by Shay Gla-On of the Embedded Microprocessor Benchmark Consortium (EEMBC) in 2009, primarily aimed at testing the core performance of processors, and is considered to have more practical value than the outdated Dhrystone standard.

The CoreMark program is written in C language and includes the following algorithms: listing (finding and sorting), mathematical matrix operations (ordinary matrix calculations), and state machines (used to determine if valid numbers are present in the input stream), and finally includes CRC (Cyclic Redundancy Check). The latest version of the CoreMark program is Version 1.0.

The testing method of the CoreMark standard is also very simple: it measures how many times the CoreMark program runs in a unit of time under a certain configuration parameter combination, with the metric unit being CoreMark/MHz. The higher the CoreMark number, the higher the performance.

2. Performance Comparison of Cortex-M Processors

ARM provides official performance comparison data for the Cortex-M series processors, including Dhrystone and CoreMark standards, as shown in the figure below.

The specific metric values for each processor are as follows:

References:

[1]. [ARM Embedded System Development] Chapter One: Dhrystone

[2]. Simple Tool for Testing CPU – Dhrystone

[3]. Introduction to Processor Performance Testing Benchmark Program (CoreMark)

[4]. Cortex-M7 Launches: Embedded, IoT and Wearables

[5]. CSDN – Markdown Table Style Settings (Cross-row Tables, Background Colors, etc.)

Source: Blog of Hengjie Jay

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