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CyC2018
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@ -187,8 +187,6 @@ GNU 计划，译为革奴计划，它的目标是创建一套完全自由的操
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## HDD
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[Decoding UCS Invicta – Part 1](https://blogs.cisco.com/datacenter/decoding-ucs-invicta-part-1)
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Hard Disk Drives(HDD) 俗称硬盘，具有以下结构：
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- 盘面（Platter）：一个硬盘有多个盘面；
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@ -200,6 +198,8 @@ Hard Disk Drives(HDD) 俗称硬盘，具有以下结构：
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<div align="center"> <img src="../pics//014fbc4d-d873-4a12-b160-867ddaed9807.jpg" width=""/> </div><br>
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[Decoding UCS Invicta – Part 1](https://blogs.cisco.com/datacenter/decoding-ucs-invicta-part-1)
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## 磁盘接口
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### 1. IDE
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299
notes/计算机操作系统.md
299
notes/计算机操作系统.md
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@ -9,7 +9,6 @@
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* [进程与线程](#进程与线程)
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* [进程状态的切换](#进程状态的切换)
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* [进程调度算法](#进程调度算法)
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* [进程调度算法实现](#进程调度算法实现)
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* [进程同步](#进程同步)
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* [经典同步问题](#经典同步问题)
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* [进程通信](#进程通信)
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@ -240,304 +239,6 @@ Linux 的系统调用主要有以下这些：
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分为硬实时和软实时，前者必须满足绝对的截止时间，后者可以容忍一定的超时。
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## 进程调度算法实现
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以下只是假象系统上的调度算法实现。源代码：[Scheduling](https://github.com/CyC2018/Algorithm/tree/master/Process-Scheduling/src)
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### 1. FCFS
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首先创建进程数据结构：
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```java
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public class Process {
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private String name;
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private long totalTime;
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private long remainTime;
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private long comeInTime;
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public Process(String name, long totalTime, long comeInTime) {
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this.name = name;
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this.totalTime = totalTime;
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this.remainTime = totalTime;
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this.comeInTime = comeInTime;
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}
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public void run(long runTime) {
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System.out.println("process " + name + " is running...");
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System.out.println("come in time : " + comeInTime);
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System.out.println("total time : " + totalTime);
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System.out.println("remain time : " + remainTime);
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System.out.println();
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remainTime -= runTime;
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try {
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Thread.sleep(runTime);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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public long getTotalTime() {
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return totalTime;
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}
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public long getRemainTime() {
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return remainTime;
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}
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public long getComeInTime() {
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return comeInTime;
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}
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}
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```
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接着创建一个进程等待队列数据结构：
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```java
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public interface ProcessQueue {
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void add(Process process);
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Process get();
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boolean isEmpty();
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}
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```
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FCFS 算法使用普通的先进先出队列即可实现该进程等待队列：
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```java
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public class FCFSProcessQueue implements ProcessQueue {
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private Queue<Process> queue = new LinkedList<>();
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@Override
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public void add(Process process) {
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queue.add(process);
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}
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@Override
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public Process get() {
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return queue.poll();
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}
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@Override
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public boolean isEmpty() {
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return queue.isEmpty();
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}
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}
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```
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接下来是调度器的实现，把它设计成可独立运行的 Thread，它对进程等待队列进行轮询，如果有进程的话就从队列中取出一个任务来执行。批处理系统中，调度器调度一个进程都直接让进程执行完毕，也就是给进程运行时间为进程的总时间。
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```java
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public class Scheduler extends Thread {
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protected ProcessQueue processQueue;
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public Scheduler(ProcessQueue processQueue) {
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this.processQueue = processQueue;
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}
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}
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```
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```java
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public class BatchScheduler extends Scheduler {
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public BatchScheduler(ProcessQueue processQueue) {
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super(processQueue);
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}
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@Override
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public void run() {
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while (true) {
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if (!processQueue.isEmpty()) {
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Process process = processQueue.get();
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process.run(process.getTotalTime());
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}
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try {
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Thread.sleep(10);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}
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}
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```
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使用一个模拟器来模拟实际场景下进程的不定时到达，每 1s 到达一个进程，并且进程的运行时间再 0s \~ 3s 之间，使得多个进程会发生竞争关系。
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```java
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public class ProcessComeEmulator extends Thread {
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private ProcessQueue processQueue;
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public ProcessComeEmulator(ProcessQueue processQueue) {
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this.processQueue = processQueue;
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}
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@Override
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public void run() {
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int processId = 0;
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while (true) {
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System.out.println("process " + processId + " is coming...");
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System.out.println();
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Process process = new Process((processId++) + "", getRandomTime(), System.currentTimeMillis());
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processQueue.add(process);
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}
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private long getRandomTime() {
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return (long) (Math.random() * 3000);
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}
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}
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```
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最后创建一个客户端来运行整个调度程序：
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```java
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public class FCFSClient {
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public static void main(String[] args) {
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ProcessQueue processQueue = new FCFSProcessQueue();
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ProcessComeEmulator processComeEmulator = new ProcessComeEmulator(processQueue);
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processComeEmulator.start();
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Scheduler scheduler = new FCFSScheduler(processQueue);
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scheduler.start();
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}
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}
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```
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执行结果如下：
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```html
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process 0 is coming...
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process 0 is running...
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come in time : 1528964425691
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total time : 1807
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remain time : 1807
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process 1 is coming...
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process 1 is running...
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come in time : 1528964426691
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total time : 2311
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remain time : 2311
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process 2 is coming...
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process 3 is coming...
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process 4 is coming...
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process 2 is running...
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come in time : 1528964427692
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total time : 2651
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remain time : 2651
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process 5 is coming...
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process 6 is coming...
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process 3 is running...
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come in time : 1528964428692
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total time : 137
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remain time : 137
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process 4 is running...
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come in time : 1528964429692
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total time : 2513
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remain time : 2513
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```
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### 2. SJF
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与 FCFS 不同的是，SJF 的进程等待队列需要使用优先级队列来实现：
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```java
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public class SJFProcessQueue implements ProcessQueue {
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private PriorityQueue<Process> processesQueue = new PriorityQueue<>(
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(o1, o2) -> (int) (o1.getTotalTime() - o2.getTotalTime()));
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@Override
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public void add(Process process) {
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processesQueue.add(process);
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}
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@Override
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public Process get() {
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return processesQueue.poll();
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}
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@Override
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public boolean isEmpty() {
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return processesQueue.isEmpty();
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}
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}
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```
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运行客户端：
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```java
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public class SJFClient {
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public static void main(String[] args) {
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ProcessQueue processQueue = new SJFProcessQueue();
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ProcessComeEmulator processComeEmulator = new ProcessComeEmulator(processQueue);
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processComeEmulator.start();
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Scheduler scheduler = new BatchScheduler(processQueue);
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scheduler.start();
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}
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}
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```
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```java
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process 0 is coming...
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process 0 is running...
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come in time : 1528964250005
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total time : 2496
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remain time : 2496
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process 1 is coming...
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process 2 is coming...
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process 1 is running...
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come in time : 1528964251006
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total time : 903
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remain time : 903
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process 3 is coming...
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process 2 is running...
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come in time : 1528964252006
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total time : 1641
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remain time : 1641
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process 4 is coming...
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process 5 is coming...
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process 4 is running...
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come in time : 1528964254007
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total time : 243
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remain time : 243
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process 5 is running...
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come in time : 1528964255007
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total time : 646
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remain time : 646
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process 3 is running...
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come in time : 1528964253006
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total time : 2772
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remain time : 2772
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```
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## 进程同步
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### 1. 临界区
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