但此时应该把那个页面换出,则需要根据一定的页面置换算法(Page Replacement Algorithm)来确定。 2.1 最佳置换(Optimal, OPT) 2.1.1 基本思想 置换以后不再被访问,或者在将来最迟才回被访问的页面,缺页中断率最低。但是该算法需要依据以后各业的使用情况,而当一个进程还未运行完成是,很难估计哪一个页面是以后不...
进程运行过程中,如果发生缺页中断,而此时内存中有没有空闲的物理块是,为了能够把所缺的页面装入内存,系统必须从内存中选择一页调出到磁盘的对换区。但此时应该把那个页面换出,则需要根据一定的页面置换算法(Page Replacement Algorithm)来确定。 2.1 最佳置换(Optimal, OPT) 2.1.1 基本思想 置换以后不再被访问,或者...
进程运行过程中,如果发生缺页中断,而此时内存中有没有空闲的物理块是,为了能够把所缺的页面装入内存,系统必须从内存中选择一页调出到磁盘的对换区。但此时应该把那个页面换出,则需要根据一定的页面置换算法(Page Replacement Algorithm)来确定。 2.1 最佳置换(Optimal, OPT) 2.1.1 基本思想 置换以后不再被访问,或者...
#include<stdio.h>#include<stdlib.h>#include#definerandom(x) (rand()%x)#defineLOG 1//1-show log 2-no show#defineTYPE 10//page types#defineNUM 20//page nums#defineSIZE 5//cache sizestructpage{intid;//page idinttime=0;//different meaning in different algorithm};structpage pageList[NUM...
(5) 理想型淘汰算法OPT(optimal replacement algorithm)。该算法淘汰在访问串中将来再也不出现的或是在离当前最远的位置上出现的页面。 RP和FIFO都是基于CPU按线性顺序访问地址空间这一假设,但是实际上CPU在很多时候并非是按线性顺序访问地址空间的,因而它们的内存利用率不高。此外FIFO算法还存在着Belady现象。LRU算...
Belady, Nelson and Shedler constructed reference strings for which page replacement algorithm FIFO produces near twice more page faults in a larger memory than in a smaller one. They formulated the conjecture that 2 is a general bound. We prove that this ratio can be arbitrarily large....
常见置换算法有随机淘汰算法(Random Glongram)、轮转法(Round Robin)和先进先出(FIFO)、最近最久未使用页面置换算法和理想型淘汰算法OPT(Optimal Replacement Algorithm)。本次所设计的模拟系统根据题目要求利用随机淘汰算法,先进先出算法和理想型淘汰算法进行页面替换,详细算法原理如下: 随机淘汰算法:在系统设计人员无法...
the impact of fifo on performance depends on the specific algorithm and scenario. in certain cases, fifo algorithms can provide efficient and fair processing of tasks. however, in other scenarios, particularly when dealing with large datasets or complex processing requirements, more sophisticated ...
FIFO (First IN, First OUT) FIFO implements a queue. A FIFO replacement algorithm links with each page the time when that page was added into the memory The oldest page is chosen when a page is going to be replaced. We can create a FIFO queue to hold all the pages present in the mem...
This project implements a simple thread-safe cache with several page replacement policies: Least Recently Used First-In/First-Out Least Frequently Used More about cache algorithms and policy you could read onWikipedia Usage Using this library is simple. It is necessary to include header with the ...