操作系统内存分配算法模拟实现

实验名称内存分配与回收算法实现同组人姓名实验性质□基本操作●验证性□综合性□设计性实验日期2010-5-17 实验成绩教师评价：实验预习□实验操作□实验结果□实验报告□其它□教师签名：一、实验目的及要求1）掌握为实现多道程序并发执行，操作系统是如何通过作业调度选择作业进入内存2）系统如何为进入内存的作业分配内存空间，实现多道作业同时驻留内存，就绪进程队列中的多个进程是如何以分式方式共享CPU，作业运行完成离开系统时，系统如何进行内存回收，计算进程周转时间。

3）掌握各种调度算法，以及实现所需的各种数据结构。

二、实验内容根据给定的动态分区分配算法流程图，用你熟悉的计算机编程语言编写一程序，该程序实现内存的合理分配后回收。

三、主要设备及软件PC、Windows2000操作系统、Linux操作系统四、实验流程、操作步骤或核心代码、算法片段1、分配算法流程出请求分配u.size 分区检索空闲分区链（表）找到大于u.size 的可用分区否？按动态分区方式进行分配修改有关数据结构返回分区号及空闲分区总和>=u.siz e进行紧筹形成连续空闲区修改有关数据结构 无法分配返2、算法模拟实现○1相关数据结构定义空闲分区块类：class FreeBlock空闲分区链类：class FreeList内存分配回收算法类：class MemoryManager测试类（主类）：class TestForMemManage○2具体实现请允许我先列出核心部分，内存分配回收算法类的实现：package com.kaiping.memorymanage;//个人包import java.util.Scanner;public class MemoryManager {FreeList flist; //空闲分区类对象public MemoryManager(){flist = new FreeList();flist.InitFBlock();}public void memAllocation(int size, String new_job_name){//内存分配（首次适应算法）FreeBlock q=flist.head;FreeBlock p=flist.head.next;while(p != null){if(size <= 0){System.out.println("\n申请的空间不能小于1！");break;}if(p.state == false && p.size >= size){q = new FreeBlock(p.size - size);p.size = size;p.state = true;p.job_name = new_job_name;q.next = p.next;p.next = q;break; //完成分配}else{p = p.next; //移动到足够分配的空闲块}}if(p == null){if(flist.flistsize >= size){System.out.println("目前尚无足够大的空闲块，系统将进行重定位操作...");relocation(); //重定向memAllocation(size,new_job_name); //重新分配内存}else{System.out.println("作业"+new_job_name+"内存尚未分配成功！");}}else{ //分配内存后可能存在大小为0的空间，将其清除System.out.println("作业"+new_job_name+"内存分配成功！");p = flist.head.next;//q = flist.head;while(p != null){if(p.size == 0){flist.deleteFBlock(p);}p = p.next;}}}private void memRecovery(FreeBlock target){ //内存回收FreeBlock p = flist.head.next;while(p != null){//回收区与插入点的前一个空闲分区相邻接if(p.next == target && p.state == false){p.size += target.size;p.next = target.next;//回收区同时与插入点的前后两个空闲分区相邻接if(!p.next.state){p.size += p.next.size;p.next = p.next.next;}break;}if(p == target){//回收区与插入点的后一空闲分区相邻接if(!p.next.state){target.size += p.next.size;target.next = p.next.next;}break; //若两不邻接，则直接跳出}p = p.next;}}private void relocation(){ //空闲资源重定向，回收空闲空间FreeBlock front_r=flist.head; //FreeBlock r=front_r.next; //当前重定向空闲块FreeBlock behind_r=r.next;while(r != null){ //将r定位到第一块空闲分区块if(r.state == false){break;}r = r.next;behind_r = r.next;front_r = front_r.next; //记录第一块空闲分区的上一块}while(behind_r != null){if(behind_r.state){front_r.next = behind_r;r.next = behind_r.next;behind_r.next = r;front_r = behind_r;}else{r.size += behind_r.size;r.next = behind_r.next;}behind_r = r.next;}System.out.println("重定向成功，继续为作业分配内存..."); }public void addJob(){ //添加作业int newSize; //新作业所需内存大小String nJobName = new String("");Scanner scanner=new Scanner(System.in);System.out.print("请输入新任务的名称：");nJobName = scanner.nextLine();System.out.print("请输入新任务所需内存大小：");newSize = scanner.nextInt();memAllocation(newSize,nJobName);}public void delJob(){ //销毁作业String cur_job_name = new String("");boolean flag = false; //指示作业是否删除成功FreeBlock q=flist.head.next;Scanner scanner=new Scanner(System.in);System.out.print("请输入需要回收的作业名称:");cur_job_name = scanner.nextLine();while(q != null){if(q.job_name == cur_job_name){q.state = false;q.job_name = "";memRecovery(q); //回收内存flag = true;break;}else{q = q.next; //找到要删除的作业的下一个结点}}if(flag){System.out.println("删除作业成功！");}else{System.out.println("删除作业未成功！");}}public void printJobInfo(){ //打印作业信息FreeBlock p = flist.head.next;int pro_num = 1; //用户程序号int mem_num = 1; //内存分区块号System.out.println("----------用户程序信息----------");while(p != null){if(p.state){System.out.println("用户程序"+pro_num+"("+p.job_name+")"+"\t占用第"+mem_num+"分区块");pro_num++;}mem_num++;p = p.next;}}public void printFreeSubareaInfo(){ //打印空闲分区信息FreeBlock p = flist.head.next;int leav_size = 0; //剩余内存大小int mem_num = 1; //内存分区块号System.out.println("----------空闲分区信息----------");System.out.println("\t分区块号\t大小");while(p != null){if(!p.state){System.out.println("\t"+mem_num+"\t"+p.size);leav_size += p.size;}mem_num++;p = p.next;}System.out.println("剩余内存总打小为"+leav_size);}}其它类的实现空闲分区块类：package com.kaiping.memorymanage;public class FreeBlock {int size; //空闲块大小boolean state; //false表示空闲，true表示已经装入作业String job_name; //装入的作业名称FreeBlock next; //下一空闲块的自引用public FreeBlock(int s){size = s;state = false;job_name = new String("");next = null;}}空闲分区链类：package com.kaiping.memorymanage;import java.util.Scanner;public class FreeList {FreeBlock fblock;FreeBlock head;int fblockNum; //空闲块数int sumMemCount; //内存总大小int flistsize; //空闲分区总和public FreeList(){fblock = null;head = new FreeBlock(0);}public boolean isEmpty(){return (fblock == null);}public void insertFBlock(int size){FreeBlock newBlock = new FreeBlock(size);if(fblock == null){fblock = newBlock;head.next = fblock;}else{fblock.next = newBlock;fblock = fblock.next;}}public void deleteFBlock(FreeBlock dblock){FreeBlock temp = head;while(temp != null){if(temp.next == dblock){temp.next = dblock.next;break;}temp = temp.next;}}public void InitFBlock(){int leavesCount; //为化入分区内存总大小int bsize=0; //分区块大小Scanner scanner=new Scanner(System.in);System.out.print("初始多大空间，请输入一整数：");sumMemCount = scanner.nextInt();leavesCount = sumMemCount;flistsize = sumMemCount; //初始空闲分区大小为内存大小System.out.print("需将内存分为多少分区块，请输入一整数：");fblockNum = scanner.nextInt();System.out.println("----------初始化内存分区----------");for(int i=1; i <= fblockNum; i++){if(i == fblockNum){insertFBlock(leavesCount);}else{System.out.print("请输入第"+i+"块分区大小：");bsize = scanner.nextInt();if(bsize >= leavesCount - i){System.out.print("您输入的数据无法保证每分区块最少有1单位内存，请重新输入：");bsize = scanner.nextInt();}insertFBlock(bsize);leavesCount -= bsize;System.out.println("余下内存大小为"+leavesCount+"，请继续分配！");}}System.out.println("分配完毕！");System.out.println("----------创建空闲分区表如下----------");System.out.println("\t分区号\t大小");FreeBlock temp = head.next;for(int i=1; i <= fblockNum; i++){System.out.println("\t"+i+"\t"+temp.size);temp = temp.next;}}}测试类（主类）：package com.kaiping.memorymanage;import java.util.Scanner;public class TestForMemManage {public static void main(String[] args) {MemoryManager mem_manage = new MemoryManager();int choice=0;Scanner scanner=new Scanner(System.in);do{System.out.println("0.退出程序");System.out.println("1.添加新作业");System.out.println("2.销毁一条作业");System.out.println("3.显示作业信息");System.out.println("4.显示空闲分区信息");System.out.print("请输入您的选择：");choice = scanner.nextInt();switch(choice){case 0:break;case 1:mem_manage.addJob();break;case 2:mem_manage.delJob();break;case 3:mem_manage.printJobInfo();break;case 4:mem_manage.printFreeSubareaInfo();break;default:System.out.println("请输入正确的选择！");}}while(choice != 0);System.out.println();System.out.println("使用愉快！期待您下次使用！");}}五、实验测试结果及心得体会1、测试结果本人主要测试内存的分配与回收以及无足够大的空闲分区块时进行的重定向操作等功能。