操作系统_内存分配与回收实验报告

西安邮电大学（计算机学院）课内实验报告实验名称：内存分配与回收专业名称：计算机科学与技术班级：计科1503学生姓名：***学号（8位）：********指导教师：***实验日期：2016年5月23日---2016年6月6日一. 实验目的及实验环境1.实验目的掌握内存分配FF，BF，WF策略及实现的思路；掌握内存回收过程及实现思路；实现内存的申请、释放的管理程序，调试运行，总结程序设计中出现的问题并找出原因，写出实验报告。

2.实验环境（1）硬件CPU：I7-6500内存：8G显示器：笔记本显示器硬盘空间：1TB（2）软件虚拟机名称及版本：Vmware操作系统名称及版本：Ubuntu Kylin 16.04编译器：gcc二. 实验内容1、实验前准备工作阅读参考资料，掌握操作系统内存管理的过程，并熟悉FF，BF，WF内存分配策略以及内存回收策略。

2、实验内容根据下发ppt内容，内存分配与回收程序要求完成如下功能，具体详细设计要求见ppt。

1 -Set memory size (default=1024)//设置内存大小2 - Select memory allocation algorithm//选择内存分配算法FF、BF、WF3 - New process//创建新进程，分配内存4 - Terminate a process//终止进程，回收内存5 - Display memory usage//显示内存当前使用情况0 – Exit//程序退出三．方案设计1．功能模块图及解释2．核心数据结构及解释struct free_block_type //空闲块{int size;int start_addr;struct free_block_type *next;};struct allocated_block //已分配的内存块{int pid;int size;int start_addr;char process_name[PROCESS_NAME_LEN];struct allocated_block *next;}；1.Set memory size (default=1024):这个模块是用来设置内存大小的，从键盘获取一个数字，并将它赋值给内存大小；若没有设置，则默认内存的大小为1024。

2.Set_algorithm：这个模块是用来设置分配算法的，共有三种算法：首次循环适配算法、最好适配算法、最差适配算法。

从键盘输入一种算法前的序号，根据算法点用不同的函数对内存进行分配；3.New_process:此模块是用来创建进程的。

从键盘输入进程号，调用fork（）创建进程并为其分配一定大小的内存，若分配成功，则将其连接到已分配链表中，否则分配失败；4.Kill_process:此模块是用来杀死进程的。

从键盘输入一个进程号，先调用find_process（）函数进行查找，若找到，则调用kill（）函数将其杀死并释放内存空间。

5.Display_mem_usage:此模块是用来显示内存的使用情况的。

将每个进程的内存使用情况显示出来，包括起始地址和内存大小；6.Do_exit:这个模块是用来结束程序的，直接调用exit()实现。

3．主要算法流程图及解释算法调用图四．测试数据及运行结果1．正常测试数据（3组）及运行结果；2．非正常测试数据（2组）及运行结果。

五．总结1．实验过程中遇到的问题及解决办法；实验过程中不会实现最佳适应算法，然后通过网上查阅别人的算法，自己研究，解决了这个问题。

2．对设计及调试过程的心得体会。

这次实验让我充分了解了内存管理的机制，进一步加深了对计算机的了解，对于以后系统的研究学习计算机起到了至关重要的作用。

六．附录：源代码（电子版）#include <stdio.h>#include <stdlib.h>#include <ctype.h>/*常量定义*/#define PROCESS_NAME_LEN 32 /*进程名长度*/#define MIN_SLICE 10 /*最小碎片的大小*/#define DEFAULT_MEM_SIZE 1024 /*内存大小*/#define DEFAULT_MEM_START 0 /*起始位置*//* 内存分配算法 */#define MA_FF 1#define MA_BF 2#define MA_WF 3/*描述每一个空闲块的数据结构*/struct free_block_type{int size;int start_addr;struct free_block_type *next;};/*每个进程分配到的内存块的描述*/struct allocated_block{int pid;int size;int start_addr;char process_name[PROCESS_NAME_LEN];struct allocated_block *next;};/*指向内存中空闲块链表的首指针*/struct free_block_type *free_block;/*进程分配内存块链表的首指针*/struct allocated_block *allocated_block_head = NULL;int mem_size=DEFAULT_MEM_SIZE; /*内存大小*/int ma_algorithm = MA_FF; /*当前分配算法*/static int pid = 0; /*初始pid*/int flag = 0; /*设置内存大小标志,防止重复设置*/ void display_menu();void do_exit();struct free_block_type *init_free_block(int mem_size);void set_mem_size();void set_algorithm();void new_process();void kill_process();void display_mem_usage();void rearrange(int choice);void abc();void rearrage_BF();void rearrage_WF();main(){char choice;pid=0;free_block = init_free_block(mem_size); //初始化空闲区display_menu();while(1) {printf("Please choice: ");fflush(stdin);choice=getchar(); //获取用户输入switch(choice) {case '1':set_mem_size(); //设置内存大小break;case '2':set_algorithm();//设置算法flag=1;break;case '3':new_process();//创建新进程flag=1; break;case '4':kill_process();//删除进程flag=1; break;case '5':display_mem_usage();//显示内存使用flag=1; break;case '0':do_exit();//释放链表并退出exit(0);default: break;}choice=getchar();}}//紧缩处理void free_memory_rearrage(int memory_reduce_size,int allocated_size) {struct free_block_type *p1,*p2;struct allocated_block *a1,*a2;if(memory_reduce_size!=0) //分配完还有小块空间{p1=free_block;p2=p1->next;p1->start_addr=0;p1->size=memory_reduce_size;p1->next=NULL;mem_size=memory_reduce_size; //}else{p2=free_block;free_block=NULL;mem_size=0;}while(p2!=NULL)//释放节点{p1=p2;p2=p2->next;free(p1);}//allocated_block 重新修改链接a1=(struct allocated_block *)malloc(sizeof(struct allocated_block));a1->pid=pid;a1->size=allocated_size;a1->start_addr=memory_reduce_size; //已申请的开始地址，从memory_reduce_size开始sprintf(a1->process_name, "PROCESS-%02d", pid);a1->next=allocated_block_head;a2=allocated_block_head;allocated_block_head=a1;while(a2!=NULL){a2->start_addr=a1->start_addr+a1->size;a1=a2;a2=a2->next;}}int allocate_mem(struct allocated_block *ab){struct free_block_type *fbt, *pre;int request_size=ab->size;//int memory_count;//计算剩余分区总内存大小fbt = pre = free_block;while((pre!=NULL)&&(request_size>pre->size))//遍历查找匹配空白区{//memory_count+=pre->size;fbt=pre;pre=pre->next;}if(!pre) //pre=pre->next结尾{if(mem_size>=request_size)/*memory_count*/{if(mem_size>=request_size+MIN_SLICE)free_memory_rearrage(mem_size-request_size,request_size); //采用紧缩技术elsefree_memory_rearrage(0,mem_size); //采用紧缩技术,空间全部分配return 0;//全部重定位,不返回上级}elsereturn -1;//分配失败!}else //内存能满足 request_size<=pre->size{if((pre->size-request_size)>MIN_SLICE)//找到可满足空闲分区且分配后剩余空间足够大，则分割{pre->size=pre->size-request_size;ab->start_addr=pre->start_addr+pre->size;}else//找到可满足空闲分区且但分配后剩余空间比较小，则一起分配，删除该节点{if(pre==fbt){fbt=pre->next;free_block=fbt;}elsefbt->next=pre->next;ab->start_addr=pre->start_addr;ab->size=pre->size;free(pre);//释放节点}}mem_size-=ab->size;//...rearrange(ma_algorithm);//分配成功，按照相应算法排序return 1;}void new_process(){struct allocated_block *ab;int size;int ret;/*ret==1表示从空闲分区分配空间成功*/if(mem_size==0){printf("内存全部分配！无法创建新进程，请先释放其他进程！\n");return;}ab=(struct allocated_block *)malloc(sizeof(struct allocated_block));if(ab==NULL){printf("No Mem!\n");exit(1);}ab->next=NULL;pid++;sprintf(ab->process_name,"PROCESS-%02d",pid);//字符串格式化ab->pid=pid;while(1){printf("Please input the memory for %s(0-%d):",ab->process_name,mem_size);scanf("%d",&size);if(size<=mem_size&&size>0){ab->size=size;break;}printf("Please input again！\n");}ret=allocate_mem(ab);//从空闲内存分配空间/*如果此时allocated_block_head尚未赋值，则赋值*/if((ret==1) &&(allocated_block_head == NULL))allocated_block_head=ab;else if(ret==1) /*分配成功，将该已分配块的描述插入已分配链表(头插<无头节点>)*/{ab->next=allocated_block_head;allocated_block_head=ab;}else if(ret==-1)/*分配不成功*/{printf("Allocation fail\n");free(ab);return;}printf("Allocation Success!\n");}struct allocated_block *find_process(int pid){struct allocated_block *p;p=allocated_block_head;while(p){if(p->pid==pid)return p;p=p->next;}return p;}/*释放ab所表示的分配区*/int free_mem(struct allocated_block *ab){int algorithm = ma_algorithm;struct free_block_type *fbt,*pre,*work;mem_size+=ab->size;fbt=(struct free_block_type *)malloc(sizeof(struct free_block_type));if(!fbt)return -1;fbt->size = ab->size;fbt->start_addr=ab->start_addr;fbt->next=NULL;rearrange(MA_FF);pre=NULL;work=free_block;//查找插入位置while((work!=NULL)&&(fbt->start_addr>work->start_addr)){pre=work;work=work->next;}if(!pre)//插入开始位置{if (!work){free_block=fbt; //}else{fbt->next=work;free_block=fbt;if(fbt->start_addr+fbt->size==work->start_addr)//2){fbt->next=work->next;fbt->size=fbt->size+work->size;free(work);}}}else{if(!work){pre->next=fbt;if(fbt->start_addr==pre->start_addr+pre->size)//1){pre->next=work;pre->size=fbt->size+pre->size;free(fbt);}}else{fbt->next=work;pre->next=fbt;// 检查并合并相邻的空闲分区if((fbt->start_addr==pre->start_addr+pre->size)&&(fbt->start_addr+fbt->size == work->start_addr))//3){pre->next=work->next;pre->size=pre->size+fbt->size+work->size;free(fbt);free(work);}else if(fbt->start_addr== pre->start_addr+pre->size)//1){pre->next=work;pre->size=pre->size+fbt->size;free(fbt);}else if(work->start_addr==fbt->start_addr+fbt->size)//2{fbt->next=work->next;fbt->size=work->size+fbt->size;free(work);}}}// 将空闲链表重新按照当前算法排序rearrange(ma_algorithm);return 1;}/*释放ab数据结构节点*/void dispose(struct allocated_block *free_ab){struct allocated_block *pre,*ab;if(free_ab==allocated_block_head)/*如果要释放第一个节点*/{allocated_block_head=free_ab->next;free(free_ab);return ;}pre=allocated_block_head;ab=allocated_block_head->next;while(ab!=free_ab){pre=ab;ab=ab->next;}pre->next=ab->next;free(ab);}void kill_process(){struct allocated_block *ab;int pid;printf("Kill process,input pid = ");scanf("%d",&pid);ab=find_process(pid);if(ab!=NULL){free_mem(ab);/*释放ab所表示的分配区*/dispose(ab);/*释放ab数据结构节点*/printf("Kill Process Success!\n");return;}printf("Kill Process Failure!\n");}/* 显示当前内存的使用情况，包括空闲区的情况和已经分配的情况 */void display_mem_usage(){struct free_block_type *fbt=free_block;struct allocated_block *ab=allocated_block_head;/* 显示空闲区 */printf("----------------------------------------------------------\n");if(fbt==NULL)printf("内存全部分配!\n");else{printf("Free Memory:\n");printf("%20s %20s\n", "\tstart_addr", " size");while(fbt!=NULL){printf("%20d %20d\n", fbt->start_addr, fbt->size);fbt=fbt->next;}}printf("----------------------------------------------------------\n");/* 显示已分配区 */if(ab==NULL)printf("尚未开始分配!\n");else{printf("\nUsed Memory:\n");printf("%10s %20s %10s %10s\n", "\tPID", " ProcessName", " start_addr ", "size");while(ab!=NULL){printf("%10d %20s %10d %10d\n", ab->pid, ab->process_name, ab->start_addr, ab->size);ab=ab->next;}}printf("----------------------------------------------------------\n");}/*按BF算法重新整理内存空闲块链表*/void rearrage_BF(){struct free_block_type *p,*p1,*p2;struct free_block_type *last_flag;p1=(struct free_block_type *)malloc(sizeof(struct free_block_type));p1->next=free_block;free_block=p1;//不改变p1,free_block指向头p1if(free_block!=NULL){for (last_flag=NULL; last_flag!=free_block; last_flag=p){for (p=p1=free_block; p1->next!=NULL&&p1->next->next!=NULL&&p1->next->next!=last_flag;p1=p1->next){if (p1->next->size > p1->next->next->size){p2 = p1->next->next;p1->next->next = p2->next; //p2->next = p1->next;p1->next = p2;p = p1->next->next;}}}}p1 = free_block;free_block = free_block->next;free(p1);p1 = NULL;}/*按WF算法重新整理内存空闲块链表*/void rearrage_WF(){struct free_block_type *p,*p1,*p2;struct free_block_type *last_flag;p1=(struct free_block_type *)malloc(sizeof(struct free_block_type));p1->next=free_block;free_block=p1;//不改变p1,free_block指向头p1if(free_block!=NULL){for (last_flag=NULL; last_flag!=free_block; last_flag=p) {for (p=p1=free_block; p1->next!=NULL&&p1->next->next!=NULL&&p1->next->next!=last_flag;p1=p1->next){if (p1->next->size < p1->next->next->size){p2 = p1->next->next;p1->next->next = p2->next; //p2->next = p1->next;p1->next = p2;p = p1->next->next;}}}}p1 = free_block;free_block = free_block->next;free(p1);p1 = NULL;}void swap(int *p ,int *q){int t;t=*p;*p=*q;*q=t;}void rearrage_FF(){struct free_block_type *tmp, *work;printf("Rearrange free blocks for FF \n");tmp = free_block;while(tmp!=NULL){ work = tmp->next;while(work!=NULL){if( work->start_addr < tmp->start_addr) { /*地址递增*/swap(&work->start_addr, &tmp->start_addr);swap(&work->size, &tmp->size);}else work=work->next;}tmp=tmp->next;}}void abc1(){struct free_block_type *p,*p1,*p2;struct free_block_type *last_flag;p1=(struct free_block_type *)malloc(sizeof(struct free_block_type));p1->next=free_block;free_block=p1;//不改变p1,free_block指向头p1if(free_block!=NULL){for (last_flag=NULL; last_flag!=free_block; last_flag=p){for (p=p1=free_block;p1->next!=NULL&&p1->next->next!=NULL &&p1->next->next!=last_flag; p1=p1->next){if (p1->next->start_addr > p1->next->next->start_addr){p2 = p1->next->next;p1->next->next = p2->next;p2->next = p1->next;p1->next = p2;p = p1->next->next;}}}}p1 = free_block;free_block = free_block->next;free(p1);p1 = NULL;}struct free_block_type *init_free_block(int mem_size){struct free_block_type *fb;fb=(struct free_block_type *)malloc(sizeof(struct free_block_type));if(fb==NULL){printf("No Mem!\n");exit(1);}fb->size=mem_size;fb->start_addr=DEFAULT_MEM_START;fb->next=NULL;return fb;}void display_menu(){printf("\n");printf(" Memory management experiment \n");printf("1 - Set memory size (default=%d)\n", DEFAULT_MEM_SIZE); printf("2 - Select memory allocation algorithm\n");printf("3 - New process \n");printf("4 - Terminate a process \n");printf("5 - Display memory usage \n");printf("0 - Exit\n");}void rearrange(int choice){switch(choice){case 1:rearrage_FF();break;case 2:rearrage_BF();break;case 3:rearrage_WF();break;}}void set_algorithm(){int algorithm;printf("\t1 - First Fit\n");printf("\t2 - Best Fit \n");printf("\t3 - Worst Fit \n");scanf("%d", &algorithm);if(algorithm>=1 && algorithm <=3)ma_algorithm=algorithm;rearrange(ma_algorithm); //按指定算法重新排列空闲区链表}void set_mem_size(){int size;if(flag!=0){printf("Cannot set memory size again or you have already started using the memory!\n");return;}printf("Total memory size =");scanf("%d", &size);if(size>0){mem_size = size;free_block->size = mem_size;}flag=1;}void do_exit(){struct free_block_type *p1,*p2;struct allocated_block *a1,*a2;p1=free_block;if(p1!=NULL){p2=p1->next;for(;p2!=NULL;p1=p2,p2=p2->next){free(p1);}free(p1);}a1=allocated_block_head;if(a1!=NULL){a2=a1->next;for(;a2!=NULL;a1=a2,a2=a2->next){free(a1);}free(a1);}}。