FirstInNotUsedFirstOut. A discard algorithm, when space is required for a new page/segment, the one that has been in primary storage the longest time (or greatest number of instructions) without being used is the first (next) to be rolled out or overwritten.; 一种淘汰算法,当一个新的页面或段请求空间时,在主存内驻留时间最长(或指令数最多) 的未被使用过的页面或段先被调出或重写。