OSTEP：进程的概念理解
第四章：进程
作业来自: ostep-homework
两个程序都只使用CPU，所以CPU的利用率是100%，测试可得：
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15Time PID: 0 PID: 1 CPU IOs
1 RUN:cpu READY 1
2 RUN:cpu READY 1
3 RUN:cpu READY 1
4 RUN:cpu READY 1
5 RUN:cpu READY 1
6 DONE RUN:cpu 1
7 DONE RUN:cpu 1
8 DONE RUN:cpu 1
9 DONE RUN:cpu 1
10 DONE RUN:cpu 1
Stats: Total Time 10
Stats: CPU Busy 10 (100.00%)
Stats: IO Busy 0 (0.00%)总共使用了11 ticks的时间，测试可得：
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12Time PID: 0 PID: 1 CPU IOs
1 RUN:cpu READY 1
2 RUN:cpu READY 1
3 RUN:cpu READY 1
4 RUN:cpu READY 1
5 DONE RUN:io 1
6 DONE WAITING 1
7 DONE WAITING 1
8 DONE WAITING 1
9 DONE WAITING 1
10 DONE WAITING 1
11* DONE RUN:io_done 1交换顺序后，在PID0进行io操作的时候，PID1会切换成RUNNING的状态，提高了CPU的利用效率，所以交换顺序重要。测试可得：
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8Time PID: 0 PID: 1 CPU IOs
1 RUN:io READY 1
2 WAITING RUN:cpu 1 1
3 WAITING RUN:cpu 1 1
4 WAITING RUN:cpu 1 1
5 WAITING RUN:cpu 1 1
6 WAITING DONE 1
7* RUN:io_done DONE 1由于加上了
SWITCH_ON_END的标签，此时PID0进行IO操作的时候CPU会空闲等待至IO操作完成，浪费了一定的时间。测试可得：1
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12Time PID: 0 PID: 1 CPU IOs
1 RUN:io READY 1
2 WAITING READY 1
3 WAITING READY 1
4 WAITING READY 1
5 WAITING READY 1
6 WAITING READY 1
7* RUN:io_done READY 1
8 DONE RUN:cpu 1
9 DONE RUN:cpu 1
10 DONE RUN:cpu 1
11 DONE RUN:cpu 1由于这次会在等待IO的时候进行进程的切换，所以在io操作时，CPU没有等待，而是切换到了另外一个进程上继续工作，提高了利用率。测试可得：
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8Time PID: 0 PID: 1 CPU IOs
1 RUN:io READY 1
2 WAITING RUN:cpu 1 1
3 WAITING RUN:cpu 1 1
4 WAITING RUN:cpu 1 1
5 WAITING RUN:cpu 1 1
6 WAITING DONE 1
7* RUN:io_done DONE 1由于IO操作的优先级不是最高的，即使io操作的WAITING结束了，也会等待CPU先将其他进程执行之后，再对IO进行切换，由于IO操作需要消耗比较多的额外时间，而这部分时间没有被CPU利用，所以系统资源没有得到有效利用。测试可得：
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32Time PID: 0 PID: 1 PID: 2 PID: 3 CPU IOs
1 RUN:io READY READY READY 1
2 WAITING RUN:cpu READY READY 1 1
3 WAITING RUN:cpu READY READY 1 1
4 WAITING RUN:cpu READY READY 1 1
5 WAITING RUN:cpu READY READY 1 1
6 WAITING RUN:cpu READY READY 1 1
7* READY DONE RUN:cpu READY 1
8 READY DONE RUN:cpu READY 1
9 READY DONE RUN:cpu READY 1
10 READY DONE RUN:cpu READY 1
11 READY DONE RUN:cpu READY 1
12 READY DONE DONE RUN:cpu 1
13 READY DONE DONE RUN:cpu 1
14 READY DONE DONE RUN:cpu 1
15 READY DONE DONE RUN:cpu 1
16 READY DONE DONE RUN:cpu 1
17 RUN:io_done DONE DONE DONE 1
18 RUN:io DONE DONE DONE 1
19 WAITING DONE DONE DONE 1
20 WAITING DONE DONE DONE 1
21 WAITING DONE DONE DONE 1
22 WAITING DONE DONE DONE 1
23 WAITING DONE DONE DONE 1
24* RUN:io_done DONE DONE DONE 1
25 RUN:io DONE DONE DONE 1
26 WAITING DONE DONE DONE 1
27 WAITING DONE DONE DONE 1
28 WAITING DONE DONE DONE 1
29 WAITING DONE DONE DONE 1
30 WAITING DONE DONE DONE 1
31* RUN:io_done DONE DONE DONE 1在使用了IMMEDIATE标签后，每次io_done之后CPU都会先切换io操作，然后用io处理的时间来处理其他进程，提高了系统资源的利用率。测试如下：
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22Time PID: 0 PID: 1 PID: 2 PID: 3 CPU IOs
1 RUN:io READY READY READY 1
2 WAITING RUN:cpu READY READY 1 1
3 WAITING RUN:cpu READY READY 1 1
4 WAITING RUN:cpu READY READY 1 1
5 WAITING RUN:cpu READY READY 1 1
6 WAITING RUN:cpu READY READY 1 1
7* RUN:io_done DONE READY READY 1
8 RUN:io DONE READY READY 1
9 WAITING DONE RUN:cpu READY 1 1
10 WAITING DONE RUN:cpu READY 1 1
11 WAITING DONE RUN:cpu READY 1 1
12 WAITING DONE RUN:cpu READY 1 1
13 WAITING DONE RUN:cpu READY 1 1
14* RUN:io_done DONE DONE READY 1
15 RUN:io DONE DONE READY 1
16 WAITING DONE DONE RUN:cpu 1 1
17 WAITING DONE DONE RUN:cpu 1 1
18 WAITING DONE DONE RUN:cpu 1 1
19 WAITING DONE DONE RUN:cpu 1 1
20 WAITING DONE DONE RUN:cpu 1 1
21* RUN:io_done DONE DONE DONE 1开放题随机，和前七题大致相同。
OSTEP：进程的概念理解
https://halc.top/p/e328a303