arm linux平台下延时函数精度测试，对usleep、nanosleep、select三种方法进行对比分析，可直接用于各种arm linux平台，需要精确延时的帮助很大-arm linux platform, precision time delay function testing, usleep, nanosleep, select three methods were compared, can be used for a variety of arm linux platform,

linux/unix下延时函数的精确度的测试代码-linux/unix time delay function of the accuracy of the test code