操作系统页面内存页面置换算法（OPT、LRU、FIFO以及Clock）的实现程序资源-CSDN文库

共22个文件

class：12个

java：6个

png：1个

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操作系统中的页面内存管理是至关重要的，它涉及到如何有效地在有限的物理内存中处理大量的虚拟内存需求。本项目实现了四种常见的页面置换算法：最优页面置换算法（OPT）、最近最少使用算法（LRU）、先进先出算法（FIFO）以及时钟算法（Clock），以帮助理解这些策略的工作原理和性能差异。 1. **最优页面置换算法（OPT）**： OPT是最理想的页面置换算法，假设系统能预知未来将要访问的页面，每次选择最远不会被使用的页面进行替换。然而，由于实际中无法预测未来，所以OPT只能作为衡量其他算法性能的标准。在实现OPT时，通常需要模拟一个预测模型来近似实现。 2. **最近最少使用算法（LRU）**： LRU基于“最近被访问过的页面更可能在未来被再次访问”的假设。当内存满时，LRU会替换最近最少使用的页面。在实现中，通常使用链表或哈希表来维护页面的访问历史，以便快速找到最久未使用的页面。 3. **先进先出算法（FIFO）**： FIFO是最简单的页面置换策略，按照页面进入内存的顺序决定何时替换。即当内存满时，最先进入内存的页面首先被替换出去。FIFO实现简单，但并不总是最优选择，可能会导致Belady's Anomaly，即增加页面分配反而导致更多的页面置换。 4. **时钟算法（Clock）**： Clock算法结合了FIFO的简单性和LRU的性能优势。它维护一个带有访问标志的循环列表，每当访问页面时，标志被设置。在需要置换时，时钟指针从当前位置开始遍历，遇到的第一个标记为未访问的页面就被替换。若所有页面都被访问过，则再重新开始。这个实现可以高效地近似LRU，但减少了存储需求。这些算法的实现通常涉及以下几个步骤： - **页面映射**：建立虚拟地址与物理地址的映射关系。 - **页面访问**：模拟程序对页面的读写操作。 - **页面替换决策**：根据所选算法，决定何时以及替换哪个页面。 - **页面调度**：将替换的页面写回磁盘，将新页面加载到内存。 - **性能评估**：通过诸如缺页率等指标评估各种算法的性能。为了实现良好的用户界面，程序可能包括图形化展示，如动态显示页面状态、置换过程，以及提供输入测试数据和查看结果的功能。此外，还可能包含性能分析工具，帮助用户对比不同算法的优劣。本项目提供了实践操作系统内存管理中页面置换策略的平台，有助于深入理解这些算法的运作机制，并可作为教学和研究的实用工具。通过比较不同算法的实际运行效果，可以更好地理解它们在内存资源有限情况下的表现，从而优化系统的性能。

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MemorySubstitute.zip （22个子文件）

MemorySubstitute

.project 392B

bin

myPackage

MainDialog$3.class 1KB

OPT.class 1KB

MainDialog$5.class 701B

MainDialog.class 6KB

FIFO.class 926B

MainDialog$2.class 2KB

CLOCK.class 916B

LRU.class 1KB

SecondPanel.class 7KB

MainDialog$1.class 671B

MainDialog$4.class 2KB

TableTableModel.class 948B

.settings

org.eclipse.jdt.core.prefs 629B

image

picture.png 799B

src

myPackage

OPT.java 1000B

FIFO.java 718B

MainDialog.java 7KB

CLOCK.java 704B

SecondPanel.java 9KB

LRU.java 990B

.classpath 301B

package myPackage; import java.awt.BasicStroke; import java.awt.Color; import java.awt.FlowLayout; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.geom.Line2D; import java.util.LinkedList; import javax.swing.ImageIcon; import javax.swing.JPanel; public class SecondPanel extends JPanel { private static final long serialVersionUID = 8241054192211241466L; SecondPanel(MainDialog mainDialog) { this.setBounds(0, 0, mainDialog.getWidth(), mainDialog.getHeight()); this.setLayout(new FlowLayout()); } private void initUnchangedPaint(Graphics g) { Graphics2D bg = (Graphics2D) g; bg.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 设置平滑 bg.setStroke(new BasicStroke(2.0f)); Line2D.Double leftLine = new Line2D.Double( (double) (1 * this.getWidth() / 10), (double) (1 * this.getHeight() / 10), (double) (1 * this.getWidth() / 10), (double) (9 * this.getHeight() / 10)); bg.draw(leftLine); Line2D.Double downLine = new Line2D.Double( (double) (1 * this.getWidth() / 10), (double) (9 * this.getHeight() / 10), (double) (9 * this.getWidth() / 10), (double) (9 * this.getHeight() / 10)); bg.draw(downLine); bg.setStroke(new BasicStroke(1.0f)); Line2D.Double rightLine = new Line2D.Double( (double) (9 * this.getWidth() / 10), (double) (1 * this.getHeight() / 10), (double) (9 * this.getWidth() / 10), (double) (9 * this.getHeight() / 10)); bg.draw(rightLine); Line2D.Double upLine = new Line2D.Double( (double) (1 * this.getWidth() / 10), (double) (1 * this.getHeight() / 10), (double) (9 * this.getWidth() / 10), (double) (1 * this.getHeight() / 10)); bg.draw(upLine); FontMetrics fm = bg.getFontMetrics(); bg.setFont(new Font(null, Font.BOLD, 15)); bg.setColor(Color.blue); String str1 = "固定分配、局部页面置换算法的比较"; bg.drawString(str1, 1 * this.getWidth() / 2 - fm.stringWidth(str1) / 2, 1 * this.getHeight() / 10 - (fm.getAscent() - fm.getDescent()) / 2); bg.setColor(Color.black); String str2 = "分配的页框数目"; bg.drawString(str2, 1 * this.getWidth() / 2 - fm.stringWidth(str2) / 2, 9 * this.getHeight() / 10 + fm.getAscent() + fm.getHeight()); bg.drawImage(new ImageIcon("image//picture.png").getImage(), 9 * this.getWidth() / 10 + 20, 1 * this.getHeight() / 10, Color.white, null); } private void initChangedPaint(Graphics g) { Graphics2D bg = (Graphics2D) g; bg.setStroke(new BasicStroke(0.5f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND, 0.5f, new float[] { 5, 10, }, 0f)); Line2D.Double dashHorLine = new Line2D.Double( (double) (1 * this.getWidth() / 10), (double) (1 * this.getHeight() / 2), (double) (9 * this.getWidth() / 10), (double) (1 * this.getHeight() / 2)); bg.draw(dashHorLine); Line2D.Double dashVerLine = new Line2D.Double( (double) (1 * this.getWidth() / 2), (double) (1 * this.getHeight() / 10), (double) (1 * this.getWidth() / 2), (double) (9 * this.getHeight() / 10)); bg.draw(dashVerLine); FontMetrics fm = bg.getFontMetrics(); String str3 = "0"; bg.drawString(str3, 1 * this.getWidth() / 2 - fm.stringWidth(str3) / 2, 9 * this.getHeight() / 10 + fm.getAscent()); bg.drawString(str3, 1 * this.getWidth() / 10 - fm.getAscent(), 1 * this.getHeight() / 2 + fm.stringWidth(str3) / 2); } private void addPaint(Graphics g) { drawLinePaint(g); drawColPaint(g, 1, 30, 1, 9); drawRowPaint(g, 5, 100, 1, 9); } private void drawLinePaint(Graphics g) { Graphics2D bg = (Graphics2D) g; bg.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 设置平滑 if (MainDialog.opts == null || MainDialog.fifos == null || MainDialog.clocks == null || MainDialog.lrus == null || MainDialog.Sequence == null) return; String lack = "页面失效率"; g.drawString(lack, this.getWidth() / 10, this.getHeight() / 10 - 10); bg.setFont(new Font(null, Font.BOLD, 10)); for (int i = 1; i < MainDialog.pageFrameNumber - 2; i++) { int K = (8 * this.getWidth() / 10) / (MainDialog.pageFrameNumber - 2); g.setColor(Color.red); g.drawLine(1 * this.getWidth() / 10 + (i + 2 - 1) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.opts[i - 1]) * (8 * this.getHeight() / 10)), 1 * this.getWidth() / 10 + (i + 2) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.opts[i]) * (8 * this.getHeight() / 10))); g.setColor(Color.BLUE); g.drawLine( 1 * this.getWidth() / 10 + (i + 2 - 1) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.clocks[i - 1]) * (8 * this.getHeight() / 10)), 1 * this.getWidth() / 10 + (i + 2) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.clocks[i]) * (8 * this.getHeight() / 10))); g.setColor(Color.GREEN); g.drawLine(1 * this.getWidth() / 10 + (i + 2 - 1) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.lrus[i - 1]) * (8 * this.getHeight() / 10)), 1 * this.getWidth() / 10 + (i + 2) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.lrus[i]) * (8 * this.getHeight() / 10))); g.setColor(Color.black); g.drawLine( 1 * this.getWidth() / 10 + (i + 2 - 1) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.fifos[i - 1]) * (8 * this.getHeight() / 10)), 1 * this.getWidth() / 10 + (i + 2) * K, (int) (this.getHeight() / 10 + (1 - MainDialog.fifos[i]) * (8 * this.getHeight() / 10))); } } private void drawRowPaint(Graphics g, int space, int arrange, double rowBegin, double rowEnd) { Graphics2D bg = (Graphics2D) g; bg.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 设置平滑 bg.setStroke(new BasicStroke(0.5f)); FontMetrics fm = bg.getFontMetrics(); int sign = 0; for (double i = 1; i <= 9; i = i + (double) (9 - 1) / ((arrange / space))) { bg.setStroke(new BasicStroke(0.5f)); Line2D.Double longLine = new Line2D.Double((double) (rowBegin * this.getWidth() / 10), (double) (i * this.getHeight() / 10), (double) ((rowBegin - 0.1) * this.getWidth() / 10), (double) (i * this.getHeight() / 10)); bg.draw(longLine); bg.drawString(sign + "", (int) ((rowBegin * this.getWidth()) / 10 - 10 - fm .getAscent()), (int) ((10 - i) * this.getHeight() / 10 + fm.stringWidth(sign + "") / 2)); sign = sign + space; bg.setStroke(new BasicStroke(0.25f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND, 0.5f, new float[] { 5, 10, }, 0f)); Line2D.Double paintDashVorLine = new Line2D.Double( (double) (rowBegin * this.getWidth() / 10), (double) (i * this.getHeight() / 10), (double) (rowEnd * this.getWidth() / 10), (double) (i * this.getHeight() / 10)); bg.draw(paintDashVorLine); } } private void drawColPaint(Graphics g, int space, int arrange, double rowBegin, double rowEnd) { Graphics2D bg = (Graphics2D) g; bg.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 设置平滑 bg.setStroke(new BasicStroke(0.5f)); FontMetrics fm = bg.getFontMetrics(); int mark = 0; int sign = 0; for (double i = 1.0; i <= 9; i = i + (double) (9 - 1) / ((arrange / space) * 4 + 1)) { if (mark % 4 == 0) { bg.setStroke(new BasicStroke(0.5f)); Line2D.Double longLine = new Line2D.Double((double) (i * this.getWidth() / 10), (double) (rowEnd * this.getHeight() / 10), (double) (i * this.getWidth() / 10), (double) ((rowEnd + 0.1) * this.getHeight() / 10)); bg.draw(longLine); bg.drawString(sign + "", (int) (i * this.getWidt

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