1. mmap
https://blog.csdn.net/qq_33611327/article/details/81738195
2. epoll
如果这篇文章说不清epoll:https://zhuanlan.zhihu.com/p/63179839
3.sendfile、零拷贝
https://www.ibm.com/developerworks/cn/linux/l-cn-zerocopy1/index.html
https://www.jianshu.com/p/fad3339e3448