linux 平台的sd卡测速工具，可以测试sd卡在开发板上的真实的读写速度，可以通过各种工具链编译从而运行在不同厂家的linux平台上(sd card speed measurement tool for the Linux platform, you can test sd card board in the development of real reading and writing speed, you can chain through a variety of tools compiled to run on the Linux platform of different manufacturers)