Linux 内存中的 Cache 真的能被回收么？
https://linux.cn/article-7310-1.html

Linux系统中的Page cache和Buffer cache
https://zhuanlan.zhihu.com/p/35277219

Cache 和 Buffer 都是缓存，主要区别是什么？
https://www.zhihu.com/question/26190832/answer/146259979

https://unix.stackexchange.com/questions/261247/how-can-i-get-the-amount-of-available-memory-portably-across-distributions

https://unix.stackexchange.com/questions/390518/what-do-the-buff-cache-and-avail-mem-fields-in-top-mean?noredirect=1&lq=1