缓存文档置换机制是电脑处理缓存内存的一种机制。

电脑内存空间的大小固定，无法容纳服务器上所有的文档，所以当有新的文档要被置换入缓存时，必须根据一定的原则来取代掉适当的文档。此原则即所谓缓存文档置换机制。

缓存文档置换方法有：

In a computer operating system that uses paging for virtual memory management, page replacement algorithms decide which memory pages to page out (swap out, write to disk) when a page of memory needs to be allocated. Paging happens when a page fault occurs and a free page cannot be used to satisfy the allocation, either because there are none, or because the number of free pages is lower than some threshold.