Pi Zi Heng Embedded: ARM Cortex-M Core (4) - Performance Indicators

1. Processor performance indicators

　　There are many performance indicators used to evaluate CPUs. Test standards with different performance focuses may produce different indicator values. The following introduces two classic test standards widely used in the embedded industry.

1.1 Dhrystone Standard

　　Dhrystone is a benchmark program proposed by Reinhold P. Weicker in 1984. Its main purpose is to test the performance of integer operations and logical operations of the processor.

　　The Dhrystone program was originally published in Ada, and later Rick Richardson developed Version 1.1 for Unix in C, which successfully promoted the widespread use of Dhrystone. The latest version of the Dhrystone program is Version 2.1, which was updated in 1988.

　　The Dhrystone standard test method is very simple, that is, how many times the Dhrystone program is run per unit time, and its indicator unit is DMIPS/MHz. MIPS is the abbreviation of Million Instructions Per Second, which means the number of machine language instructions processed per second in the millions. The D in DMIPS is the abbreviation of Dhrystone, which represents the MIPS under the Dhrystone standard test method.

1.2 CoreMark Standard

　　CoreMark is a benchmark program proposed by Shay Gla-On of the Embedded Microprocessor Benchmark Evaluation Association EEMBC in 2009. Its main goal is to test the core performance of processors. This standard is considered to be more practical than the outdated Dhrystone standard.

　　The CoreMark program is written in C and contains the following algorithms: enumeration (search and sort), mathematical matrix operations (normal matrix operations) and state machines (used to determine whether the input stream contains valid numbers), and finally CRC (cyclic redundancy check). The latest version of the CoreMark program is Version 1.0.

　　The CoreMark standard test method is also very simple, that is, how many times the CoreMark program is run per unit time under a certain configuration parameter combination, and its indicator unit is CoreMark/MHz. The higher the CoreMark number, the higher the performance.
　

2. Performance comparison of Cortex-M processors

　　ARM provides an official performance comparison bar chart of the Cortex-M series processors:

　　The specific indicator values ​​of each processor are as follows:

　　The latest ARM official indicator values ​​in June 2019 are as follows:

References:

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

[2].  Simple tool for testing CPU - dhrystone

[3].  Introduction to the processor performance test benchmark program (CoreMark)

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

[5].  CSDN-markdown table style settings (cross-row tables, background color, etc.)