某系统采用动态分区分配方式管理内存,内存空间为 640KB,低端40KB 存放 OS。系统为用户作业分配空间时,从低地址区开始。对下列作业请求序列,画图表示使用首次适应算法进行内存分配和回收后内存的最终映像。作业请求序列如下 : 作业 1 申请 200KB,作业 2 申请 70KB ; 作业 3 申请 150KB,作业 2 释放 70KB ; 作业 4 申请 80KB,作业 3 释放 150KB ; 作业 5 申请 100KB,作业 6 申请 60KB ; 作业 7 申请 50KB,作业 6 释放 60KB。
时间: 2024-01-27 12:03:56 浏览: 86
以下是使用首次适应算法进行内存分配和回收后内存的最终映像:
初始状态:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | | | | | | | |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 1 申请 200KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 1 | 1 | | | |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 2 申请 70KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 1 | 1 | 2 | 2 | |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 3 申请 150KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 1 | 1 | 2 | 2 | 3 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 2 释放 70KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 1 | 1 | | 2 | 3 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 4 申请 80KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 1 | 1 | 4 | 2 | 3 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 3 释放 150KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 3 | 4 | 2 | |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 5 申请 100KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 3 | 4 | 2 | 5 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 6 申请 60KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 3 | 4 | 6 | 5 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 7 申请 50KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 7 | 4 | 6 | 5 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
作业 6 释放 60KB:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 7 | 4 | | 5 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```
最终状态:
```
+--------+--------+--------+--------+--------+--------+--------+--------+
| OS | 1 | 1 | 3 | 7 | 4 | | 5 |
+--------+--------+--------+--------+--------+--------+--------+--------+
0 40K 240K 390K 470K 570K 670K 740K 640K
```