传统的os 比如ucos 这种维护了一个头为单指针的双向链表，这样导致链表插入到尾部的速度很慢，得不偿失，所以raw os 采用了头为双指针的双向链表，插入速度更快。-Traditional OS such as UCOS the maintain a head for a single needle two-way linked list. As a result, the linked list insertion to the tail of the speed is very slow,

aw os 的基础链表是双向循环链表，这样的好处是插到尾部速度非常快，有些传统的os 采用了单个指针头的双向链表，虽然这样省了4个字节指针，但是算法复杂了，插入到尾部时间不确定，意义不大。-Aw OS based list is a circular doubly linked list, such benefits is inserted into the tail velocity is very fast, some traditional OS uses a single pointer