驱动调度实验报告

南通大学计算机科学与技术学院

操作系统

驱动调度实验报告

班级___________计091___________

姓名__________ _ _______ _

学号____________ _

指导教师戴树贵

一、实验内容

模拟电梯调度算法、先来先服务算法、最短查找时间算法，实现对磁盘的驱动调度。

二、实验目的

1. 进一步理解磁盘调度算法的相关内容

2. 了解磁盘寻址的方法

3. 通过编程掌握磁盘调度算法的运行方式

三、实验环境

Microsoft Visual Basic 6.0 中文版

四、实验方法内容

1.实验方法

1）使用流程图描述演示程序的设计思想；

2）选取c/c++、Java等计算机语言，编程调试，最终给出运行正确的程序。

算法

#include<stdio.h>

#include<stdlib.h>

#include<time.h>

#include<math.h>

#define DISKMAX 1000

#define DISKTOTAL 1000

#define OK 1

#define ERROR -1

int cmp ( const void *a , const void *b ) /**/

{

return *(int *)a - *(int *)b;

}

void SetBaseDisk(int *base_num){/*设置磁盘磁道数*/

int i;

printf("\ninput number of base disk(1~%d):",DISKMAX);

scanf("%d",base_num);

if(*base_num<=0||*base_num>DISKMAX){printf("ERROR!");exit(0);}

printf("\nThe base disk is:\n");

for(i=0;i<*base_num;i++){

printf(" %d",i);

}

void SetRequestDisk(int *R,int *request_num,int base_num){/*设置请求访问磁道数*/

int i;

srand(time(NULL));

printf("\ninput number of request disk(1~%d)",DISKTOTAL);

scanf("%d",request_num);

if(*request_num<=0||*request_num>DISKTOTAL){printf("ERROR!");exit(0);}

printf("\nSystem creates stochastic numbers for request disk :\n");

for(i=0;i<*request_num;i++){

R[i]=rand()%(base_num-1);//生成随机数

printf(" %d",R[i]);

}

void SetPresentDisk(int *present_disk,int *base_num){/*设置当前磁道*/

printf("\ninput present disk number(0~%d):",*base_num-1);

scanf("%d",present_disk);

if(*present_disk<0||*present_disk>=*base_num){printf("ERROR!");exit(0);}

}

/*先到先服务磁盘调度*/

void FCFS(int *R,int present_disk,int request_num){

int i;

int count=0; //磁头移动总次数

int step; //访问下一个磁道磁头移动次数

printf("\nMoving Order Moving Path Moving Steps");

step=abs(present_disk-R[0]); /*绝对值*/

count+=step;

printf("\n 1 %d---->%d %d",present_disk,R[0], step); /*输出访问轨迹*/

for(i=0;i<request_num-1;i++){ /*遍历数组*/

step=abs(R[i]-R[i+1]);

count+=step;

printf("\n %d %d---->%d %d",i+2,R[i],R[i+1], step);

}

printf("\nTotal moving steps:%d",count); /*输出磁头总移动次数*/

printf("\nAverage moving steps:%d",count/request_num); /*平均移动次数*/

}

int Sort(int *R,int request_num,int present_disk){/*调用库函数的快速排序函数*/

R[request_num]=present_disk;//加入当前磁道

qsort(R,request_num+1,sizeof(R[0]),cmp);

return 1;

}

int SearchPresent(int *R,int request_num ,int present_disk){/*二分查找法,寻找当前磁道*/

int left,right,middle;

left=0;

right=request_num;

while(left<=right){

middle=(left+right)/2;

if(present_disk==R[middle])return middle;

if(present_disk>R[middle])left=middle+1;

else right=middle-1;

}

return -1;

}

/*最短寻道时间优先算法*/

void SSTF(int *R,int present_disk,int request_num)

{int i=0;

int temp,key;

int count=0,step=0;

int up=0,down=0;

int up_step=0,down_step=0;

key=SearchPresent(R,request_num , present_disk); /*查找当前磁道*/

printf("\nMoving Order Moving Path Moving Steps");

while(key!=0&&key!=request_num){ /*磁道未到头或尾*/

i++;

if((R[key]-R[key-1-down])<(R[key+1+up]-R[key])){ /*左边的磁道比右边的磁道近*/

temp=key-1-down; /*记录下一个磁道*/

down_step++;

down=0;

up=down_step+up_step;

}

else { /*右边的磁道比左边的磁道近*/

temp=key+1+up; /*记录下一个磁道*/

up_step++;

up=0;

down=up_step+down_step;

}

step=abs(R[key]-R[temp]);

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[temp], step);

key=temp;

}

if(key==0){ /*当前磁头在头*/

i++;

temp=key+1+up; /*记录下一个将要访问的磁道*/

step=abs(R[key]-R[temp]);

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[temp], step);

key=temp;

while(key!=request_num){

i++;

step=R[key+1]-R[key];

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[key+1], step);

key++;

}

else{ /*当前磁头在尾*/

i++;

temp=key-1-down; /*记录下一个将要访问的磁道*/

step=abs(R[key]-R[temp]);

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[temp], step);

key=temp;

while(key!=0){

i++;

step=R[key]-R[key-1];

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[key-1], step);

key--;

}

printf("\nTotal moving steps:%d",count);

printf("\nAverage moving steps:%d",count/request_num);

}

/*电梯扫描算法*/

void SCAN(int *R,int present_disk,int request_num){

int i=0;

int temp,key;

int count=0,step=0;

key=SearchPresent(R,request_num , present_disk); /*查找当前磁道*/

temp=key;

if(key==request_num){ /*当前磁头在磁道头*/ while(key!=0){ /*向内移动*/

step=R[key]-R[key-1];

count+=step;

printf("\n %d %d---->%d %d",i+1,R[key],R[key-1], step); key--;

i++;

}

else if(key==0){ /*当前磁头在磁道尾*/

while(key!=request_num){

step=R[key+1]-R[key];

count+=step;

printf("\n %d %d---->%d %d",i+1,R[key],R[key+1], step); key++;

i++;

}

else{ /*当前磁头不在头或尾*/

while(key!=0){ /*向内移动*/

step=R[key]-R[key-1];

count+=step;

printf("\n %d %d---->%d %d",i+1,R[key],R[key-1], step); key--;

i++;

}

i++;

step=R[temp+1]-R[key];

count+=step;

printf("\n %d %d---->%d %d",i,R[key],R[temp+1], step); key=temp+1;

while(key!=request_num){

step=R[key+1]-R[key];

count+=step;

printf("\n %d %d---->%d %d",i+1,R[key],R[key+1], step); key++;

i++;

}

printf("\nTotal moving steps:%d",count);

printf("\nAverage moving steps:%d",count/request_num);

}

int main(){

int R[DISKTOTAL];

int base_num,request_num,present_disk;

int choose;

int flag=0;

SetBaseDisk( &base_num);

SetRequestDisk(R,&request_num,base_num);

SetPresentDisk(&present_disk,&base_num);

do{

printf("\n/*********************************/");

printf("\n\n1.先到先服务FCFS磁盘调度算法");

printf("\n\n2.最短寻道时间优先SSTF磁盘调度算法");

printf("\n\n3.电梯算法磁盘调度算法");

printf("\n\n4.退出.");

printf("\n\n/*******************************/");

printf("\n\n请输入您的选择:(1 , 2 , 3 ,4 )");

scanf("%d",&choose);//输入选择

switch(choose){

case 1:{

FCFS(R,present_disk,request_num);

}break;

case 2:{

if(flag==0)flag=Sort(R,request_num,present_disk); //排序

SSTF(R,present_disk,request_num);

}break;

case 3:{

if(flag==0)flag=Sort(R,request_num,present_disk); //排序

SCAN(R,present_disk,request_num);

}break;

}/*switch*/

}

while(choose>=1&&choose<4);

printf("\n再见！");

return 0;

}

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