mirror of
https://github.com/LearningOS/rust-based-os-comp2022.git
synced 2026-02-08 04:43:27 +08:00
538 lines
41 KiB
HTML
538 lines
41 KiB
HTML
<!doctype html>
|
||
<html class="no-js" lang="zh_CN">
|
||
<head><meta charset="utf-8"/>
|
||
<meta name="viewport" content="width=device-width,initial-scale=1"/>
|
||
<meta name="color-scheme" content="light dark"><link rel="index" title="索引" href="../genindex.html" /><link rel="search" title="搜索" href="../search.html" /><link rel="next" title="chapter3练习" href="5exercise.html" /><link rel="prev" title="管理多道程序" href="3multiprogramming.html" />
|
||
|
||
<meta name="generator" content="sphinx-4.1.2, furo 2021.08.31"/>
|
||
<title>分时多任务系统 - Open-Source-OS-Training-Camp-2022 文档</title>
|
||
<link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
|
||
<link rel="stylesheet" type="text/css" href="../_static/styles/furo.css?digest=c7c65a82b42f6b978e58466c1e9ef2509836d916" />
|
||
<link rel="stylesheet" type="text/css" href="../_static/tabs.css" />
|
||
<link rel="stylesheet" type="text/css" href="../_static/styles/furo-extensions.css?digest=16fb25fabf47304eee183a5e9af80b1ba98259b1" />
|
||
<link rel="stylesheet" type="text/css" href="../_static/my_style.css" />
|
||
|
||
|
||
|
||
|
||
<style>
|
||
body {
|
||
--color-code-background: #f8f8f8;
|
||
--color-code-foreground: black;
|
||
|
||
}
|
||
body[data-theme="dark"] {
|
||
--color-code-background: #202020;
|
||
--color-code-foreground: #d0d0d0;
|
||
|
||
}
|
||
@media (prefers-color-scheme: dark) {
|
||
body:not([data-theme="light"]) {
|
||
--color-code-background: #202020;
|
||
--color-code-foreground: #d0d0d0;
|
||
|
||
}
|
||
}
|
||
</style></head>
|
||
<body>
|
||
<script>
|
||
document.body.dataset.theme = localStorage.getItem("theme") || "auto";
|
||
</script>
|
||
|
||
<svg xmlns="http://www.w3.org/2000/svg" style="display: none;">
|
||
<symbol id="svg-toc" viewBox="0 0 24 24">
|
||
<title>Contents</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round">
|
||
<path stroke="none" d="M0 0h24v24H0z" />
|
||
<line x1="4" y1="6" x2="20" y2="6" />
|
||
<line x1="10" y1="12" x2="20" y2="12" />
|
||
<line x1="6" y1="18" x2="20" y2="18" />
|
||
</svg>
|
||
</symbol>
|
||
<symbol id="svg-menu" viewBox="0 0 24 24">
|
||
<title>Menu</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather-menu">
|
||
<line x1="3" y1="12" x2="21" y2="12"></line>
|
||
<line x1="3" y1="6" x2="21" y2="6"></line>
|
||
<line x1="3" y1="18" x2="21" y2="18"></line>
|
||
</svg>
|
||
</symbol>
|
||
<symbol id="svg-arrow-right" viewBox="0 0 24 24">
|
||
<title>Expand</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather-chevron-right">
|
||
<polyline points="9 18 15 12 9 6"></polyline>
|
||
</svg>
|
||
</symbol>
|
||
<symbol id="svg-sun" viewBox="0 0 24 24">
|
||
<title>Light mode</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" class="feather-sun">
|
||
<circle cx="12" cy="12" r="5"></circle>
|
||
<line x1="12" y1="1" x2="12" y2="3"></line>
|
||
<line x1="12" y1="21" x2="12" y2="23"></line>
|
||
<line x1="4.22" y1="4.22" x2="5.64" y2="5.64"></line>
|
||
<line x1="18.36" y1="18.36" x2="19.78" y2="19.78"></line>
|
||
<line x1="1" y1="12" x2="3" y2="12"></line>
|
||
<line x1="21" y1="12" x2="23" y2="12"></line>
|
||
<line x1="4.22" y1="19.78" x2="5.64" y2="18.36"></line>
|
||
<line x1="18.36" y1="5.64" x2="19.78" y2="4.22"></line>
|
||
</svg>
|
||
</symbol>
|
||
<symbol id="svg-moon" viewBox="0 0 24 24">
|
||
<title>Dark mode</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" class="icon-tabler-moon">
|
||
<path stroke="none" d="M0 0h24v24H0z" fill="none" />
|
||
<path d="M12 3c.132 0 .263 0 .393 0a7.5 7.5 0 0 0 7.92 12.446a9 9 0 1 1 -8.313 -12.454z" />
|
||
</svg>
|
||
</symbol>
|
||
<symbol id="svg-sun-half" viewBox="0 0 24 24">
|
||
<title>Auto light/dark mode</title>
|
||
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor"
|
||
stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" class="icon-tabler-shadow">
|
||
<path stroke="none" d="M0 0h24v24H0z" fill="none"/>
|
||
<circle cx="12" cy="12" r="9" />
|
||
<path d="M13 12h5" />
|
||
<path d="M13 15h4" />
|
||
<path d="M13 18h1" />
|
||
<path d="M13 9h4" />
|
||
<path d="M13 6h1" />
|
||
</svg>
|
||
</symbol>
|
||
</svg>
|
||
|
||
<input type="checkbox" class="sidebar-toggle" name="__navigation" id="__navigation">
|
||
<input type="checkbox" class="sidebar-toggle" name="__toc" id="__toc">
|
||
<label class="overlay sidebar-overlay" for="__navigation">
|
||
<div class="visually-hidden">Hide navigation sidebar</div>
|
||
</label>
|
||
<label class="overlay toc-overlay" for="__toc">
|
||
<div class="visually-hidden">Hide table of contents sidebar</div>
|
||
</label>
|
||
|
||
|
||
|
||
<div class="page">
|
||
<header class="mobile-header">
|
||
<div class="header-left">
|
||
<label class="nav-overlay-icon" for="__navigation">
|
||
<div class="visually-hidden">Toggle site navigation sidebar</div>
|
||
<i class="icon"><svg><use href="#svg-menu"></use></svg></i>
|
||
</label>
|
||
</div>
|
||
<div class="header-center">
|
||
<a href="../index.html"><div class="brand">Open-Source-OS-Training-Camp-2022 文档</div></a>
|
||
</div>
|
||
<div class="header-right">
|
||
<div class="theme-toggle-container theme-toggle-header">
|
||
<button class="theme-toggle">
|
||
<div class="visually-hidden">Toggle Light / Dark / Auto color theme</div>
|
||
<svg class="theme-icon-when-auto"><use href="#svg-sun-half"></use></svg>
|
||
<svg class="theme-icon-when-dark"><use href="#svg-moon"></use></svg>
|
||
<svg class="theme-icon-when-light"><use href="#svg-sun"></use></svg>
|
||
</button>
|
||
</div>
|
||
<label class="toc-overlay-icon toc-header-icon" for="__toc">
|
||
<div class="visually-hidden">Toggle table of contents sidebar</div>
|
||
<i class="icon"><svg><use href="#svg-toc"></use></svg></i>
|
||
</label>
|
||
</div>
|
||
</header>
|
||
<aside class="sidebar-drawer">
|
||
<div class="sidebar-container">
|
||
|
||
<div class="sidebar-sticky"><a class="sidebar-brand" href="../index.html">
|
||
|
||
|
||
<span class="sidebar-brand-text">Open-Source-OS-Training-Camp-2022 文档</span>
|
||
|
||
</a><form class="sidebar-search-container" method="get" action="../search.html" role="search">
|
||
<input class="sidebar-search" placeholder=搜索 name="q" aria-label="搜索">
|
||
<input type="hidden" name="check_keywords" value="yes">
|
||
<input type="hidden" name="area" value="default">
|
||
</form>
|
||
<div id="searchbox"></div><div class="sidebar-scroll"><div class="sidebar-tree">
|
||
<p class="caption" role="heading"><span class="caption-text">正文</span></p>
|
||
<ul class="current">
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../0setup-devel-env.html">第零章：实验环境配置</a><input class="toctree-checkbox" id="toctree-checkbox-1" name="toctree-checkbox-1" role="switch" type="checkbox"/><label for="toctree-checkbox-1"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter1/index.html">第一章：应用程序与基本执行环境</a><input class="toctree-checkbox" id="toctree-checkbox-2" name="toctree-checkbox-2" role="switch" type="checkbox"/><label for="toctree-checkbox-2"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter1/0intro.html">引言</a></li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter1/1app-ee-platform.html">应用程序执行环境与平台支持</a><input class="toctree-checkbox" id="toctree-checkbox-3" name="toctree-checkbox-3" role="switch" type="checkbox"/><label for="toctree-checkbox-3"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter1/2remove-std.html">移除标准库依赖</a><input class="toctree-checkbox" id="toctree-checkbox-4" name="toctree-checkbox-4" role="switch" type="checkbox"/><label for="toctree-checkbox-4"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter1/3mini-rt-usrland.html">构建用户态执行环境</a><input class="toctree-checkbox" id="toctree-checkbox-5" name="toctree-checkbox-5" role="switch" type="checkbox"/><label for="toctree-checkbox-5"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter1/4mini-rt-baremetal.html">构建裸机执行环境</a><input class="toctree-checkbox" id="toctree-checkbox-6" name="toctree-checkbox-6" role="switch" type="checkbox"/><label for="toctree-checkbox-6"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter2/index.html">第二章：批处理系统</a><input class="toctree-checkbox" id="toctree-checkbox-7" name="toctree-checkbox-7" role="switch" type="checkbox"/><label for="toctree-checkbox-7"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter2/0intro.html">引言</a></li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter2/2application.html">实现应用程序</a><input class="toctree-checkbox" id="toctree-checkbox-8" name="toctree-checkbox-8" role="switch" type="checkbox"/><label for="toctree-checkbox-8"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter2/3batch-system.html">实现批处理操作系统</a><input class="toctree-checkbox" id="toctree-checkbox-9" name="toctree-checkbox-9" role="switch" type="checkbox"/><label for="toctree-checkbox-9"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2 has-children"><a class="reference internal" href="../chapter2/4trap-handling.html">实现特权级的切换</a><input class="toctree-checkbox" id="toctree-checkbox-10" name="toctree-checkbox-10" role="switch" type="checkbox"/><label for="toctree-checkbox-10"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 current has-children"><a class="reference internal" href="index.html">第三章：多道程序与分时多任务</a><input checked="" class="toctree-checkbox" id="toctree-checkbox-11" name="toctree-checkbox-11" role="switch" type="checkbox"/><label for="toctree-checkbox-11"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="current">
|
||
<li class="toctree-l2"><a class="reference internal" href="0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="1multi-loader.html">多道程序放置与加载</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="2task-switching.html">任务切换</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="3multiprogramming.html">管理多道程序</a></li>
|
||
<li class="toctree-l2 current current-page"><a class="current reference internal" href="#">分时多任务系统</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="5exercise.html">chapter3练习</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter4/index.html">第四章：地址空间</a><input class="toctree-checkbox" id="toctree-checkbox-12" name="toctree-checkbox-12" role="switch" type="checkbox"/><label for="toctree-checkbox-12"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/3sv39-implementation-1.html">实现 SV39 多级页表机制（上）</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/4sv39-implementation-2.html">实现 SV39 多级页表机制（下）</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/5kernel-app-spaces.html">内核与应用的地址空间</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/6multitasking-based-on-as.html">基于地址空间的分时多任务</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter4/7exercise.html">chapter4练习</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter5/index.html">第五章：进程及进程管理</a><input class="toctree-checkbox" id="toctree-checkbox-13" name="toctree-checkbox-13" role="switch" type="checkbox"/><label for="toctree-checkbox-13"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter5/0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter5/1process.html">与进程有关的重要系统调用</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter5/2core-data-structures.html">进程管理的核心数据结构</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter5/3implement-process-mechanism.html">进程管理机制的设计实现</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter5/4exercise.html">chapter5练习</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter6/index.html">第六章：文件系统与I/O重定向</a><input class="toctree-checkbox" id="toctree-checkbox-14" name="toctree-checkbox-14" role="switch" type="checkbox"/><label for="toctree-checkbox-14"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/1file-descriptor.html">文件与文件描述符</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/1fs-interface.html">文件系统接口</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/2fs-implementation-1.html">简易文件系统 easy-fs (上)</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/2fs-implementation-2.html">简易文件系统 easy-fs (下)</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/3using-easy-fs-in-kernel.html">在内核中使用 easy-fs</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter6/4exercise.html">chapter6练习</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter7/index.html">第七章：进程间通信</a><input class="toctree-checkbox" id="toctree-checkbox-15" name="toctree-checkbox-15" role="switch" type="checkbox"/><label for="toctree-checkbox-15"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter7/0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter7/1pipe.html">管道</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter7/2cmdargs-and-redirection.html">命令行参数与标准 I/O 重定向</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter7/3exercise.html">chapter7练习</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../chapter8/index.html">第八章：并发</a><input class="toctree-checkbox" id="toctree-checkbox-16" name="toctree-checkbox-16" role="switch" type="checkbox"/><label for="toctree-checkbox-16"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/0intro.html">引言</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/1thread-kernel.html">内核态的线程管理</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/2lock.html">锁机制</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/3semaphore.html">信号量机制</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/4condition-variable.html">条件变量机制</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="../chapter8/5exercise.html">chapter8 练习</a></li>
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
<p class="caption" role="heading"><span class="caption-text">附录</span></p>
|
||
<ul>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../appendix-a/index.html">附录 A：Rust 系统编程资料</a><input class="toctree-checkbox" id="toctree-checkbox-17" name="toctree-checkbox-17" role="switch" type="checkbox"/><label for="toctree-checkbox-17"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../appendix-b/index.html">附录 B：常见工具的使用方法</a><input class="toctree-checkbox" id="toctree-checkbox-18" name="toctree-checkbox-18" role="switch" type="checkbox"/><label for="toctree-checkbox-18"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../appendix-c/index.html">附录 C：深入机器模式：RustSBI</a><input class="toctree-checkbox" id="toctree-checkbox-19" name="toctree-checkbox-19" role="switch" type="checkbox"/><label for="toctree-checkbox-19"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1"><a class="reference internal" href="../appendix-d/index.html">附录 D：RISC-V相关信息</a></li>
|
||
</ul>
|
||
<p class="caption" role="heading"><span class="caption-text">开发注记</span></p>
|
||
<ul>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../setup-sphinx.html">修改和构建本项目</a><input class="toctree-checkbox" id="toctree-checkbox-20" name="toctree-checkbox-20" role="switch" type="checkbox"/><label for="toctree-checkbox-20"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1 has-children"><a class="reference internal" href="../rest-example.html">reStructuredText 基本语法</a><input class="toctree-checkbox" id="toctree-checkbox-21" name="toctree-checkbox-21" role="switch" type="checkbox"/><label for="toctree-checkbox-21"><div class="visually-hidden">Toggle child pages in navigation</div><i class="icon"><svg><use href="#svg-arrow-right"></use></svg></i></label><ul class="simple">
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
|
||
</div>
|
||
</div>
|
||
</div>
|
||
|
||
</div>
|
||
</aside>
|
||
<div class="main">
|
||
<div class="content">
|
||
<article role="main">
|
||
<div class="content-icon-container">
|
||
<div class="theme-toggle-container theme-toggle-content">
|
||
<button class="theme-toggle">
|
||
<div class="visually-hidden">Toggle Light / Dark / Auto color theme</div>
|
||
<svg class="theme-icon-when-auto"><use href="#svg-sun-half"></use></svg>
|
||
<svg class="theme-icon-when-dark"><use href="#svg-moon"></use></svg>
|
||
<svg class="theme-icon-when-light"><use href="#svg-sun"></use></svg>
|
||
</button>
|
||
</div>
|
||
<label class="toc-overlay-icon toc-content-icon" for="__toc">
|
||
<div class="visually-hidden">Toggle table of contents sidebar</div>
|
||
<i class="icon"><svg><use href="#svg-toc"></use></svg></i>
|
||
</label>
|
||
</div>
|
||
<div class="section" id="id1">
|
||
<h1>分时多任务系统<a class="headerlink" href="#id1" title="永久链接至标题">¶</a></h1>
|
||
<p>现代的任务调度算法基本都是抢占式的，它要求每个应用只能连续执行一段时间，然后内核就会将它强制性切换出去。
|
||
一般将 <strong>时间片</strong> (Time Slice) 作为应用连续执行时长的度量单位，每个时间片可能在毫秒量级。
|
||
简单起见，我们使用 <strong>时间片轮转算法</strong> (RR, Round-Robin) 来对应用进行调度。</p>
|
||
<div class="section" id="id2">
|
||
<h2>时钟中断与计时器<a class="headerlink" href="#id2" title="永久链接至标题">¶</a></h2>
|
||
<p>实现调度算法需要计时。RISC-V 要求处理器维护时钟计数器 <code class="docutils literal notranslate"><span class="pre">mtime</span></code>，还有另外一个 CSR <code class="docutils literal notranslate"><span class="pre">mtimecmp</span></code> 。
|
||
一旦计数器 <code class="docutils literal notranslate"><span class="pre">mtime</span></code> 的值超过了 <code class="docutils literal notranslate"><span class="pre">mtimecmp</span></code>，就会触发一次时钟中断。</p>
|
||
<p>运行在 M 特权级的 SEE 已经预留了相应的接口，基于此编写的 <code class="docutils literal notranslate"><span class="pre">get_time</span></code> 函数可以取得当前 <code class="docutils literal notranslate"><span class="pre">mtime</span></code> 计数器的值；</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="c1">// os/src/timer.rs</span>
|
||
|
||
<span class="k">use</span><span class="w"> </span><span class="n">riscv</span>::<span class="n">register</span>::<span class="n">time</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">get_time</span><span class="p">()</span><span class="w"> </span>-> <span class="kt">usize</span> <span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">time</span>::<span class="n">read</span><span class="p">()</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p>在 10 ms 后设置时钟中断的代码如下：</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="linenos"> 1</span><span class="c1">// os/src/sbi.rs</span>
|
||
<span class="linenos"> 2</span>
|
||
<span class="linenos"> 3</span><span class="k">const</span><span class="w"> </span><span class="n">SBI_SET_TIMER</span>: <span class="kt">usize</span> <span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="linenos"> 4</span>
|
||
<span class="linenos"> 5</span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">set_timer</span><span class="p">(</span><span class="n">timer</span>: <span class="kt">usize</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="linenos"> 6</span><span class="w"> </span><span class="n">sbi_call</span><span class="p">(</span><span class="n">SBI_SET_TIMER</span><span class="p">,</span><span class="w"> </span><span class="n">timer</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
|
||
<span class="linenos"> 7</span><span class="p">}</span><span class="w"></span>
|
||
<span class="linenos"> 8</span>
|
||
<span class="linenos"> 9</span><span class="c1">// os/src/timer.rs</span>
|
||
<span class="linenos">10</span>
|
||
<span class="linenos">11</span><span class="k">use</span><span class="w"> </span><span class="k">crate</span>::<span class="n">config</span>::<span class="n">CLOCK_FREQ</span><span class="p">;</span><span class="w"></span>
|
||
<span class="linenos">12</span><span class="k">const</span><span class="w"> </span><span class="n">TICKS_PER_SEC</span>: <span class="kt">usize</span> <span class="o">=</span><span class="w"> </span><span class="mi">100</span><span class="p">;</span><span class="w"></span>
|
||
<span class="linenos">13</span>
|
||
<span class="linenos">14</span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">set_next_trigger</span><span class="p">()</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="linenos">15</span><span class="w"> </span><span class="n">set_timer</span><span class="p">(</span><span class="n">get_time</span><span class="p">()</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">CLOCK_FREQ</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">TICKS_PER_SEC</span><span class="p">);</span><span class="w"></span>
|
||
<span class="linenos">16</span><span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<ul>
|
||
<li><p>第 5 行， <code class="docutils literal notranslate"><span class="pre">sbi</span></code> 子模块有一个 <code class="docutils literal notranslate"><span class="pre">set_timer</span></code> 调用，用来设置 <code class="docutils literal notranslate"><span class="pre">mtimecmp</span></code> 的值。</p></li>
|
||
<li><p>第 14 行， <code class="docutils literal notranslate"><span class="pre">timer</span></code> 子模块的 <code class="docutils literal notranslate"><span class="pre">set_next_trigger</span></code> 函数对 <code class="docutils literal notranslate"><span class="pre">set_timer</span></code> 进行了封装，
|
||
它首先读取当前 <code class="docutils literal notranslate"><span class="pre">mtime</span></code> 的值，然后计算出 10ms 之内计数器的增量，再将 <code class="docutils literal notranslate"><span class="pre">mtimecmp</span></code> 设置为二者的和。
|
||
这样，10ms 之后一个 S 特权级时钟中断就会被触发。</p>
|
||
<p>至于增量的计算方式， <code class="docutils literal notranslate"><span class="pre">CLOCK_FREQ</span></code> 是一个预先获取到的各平台不同的时钟频率，单位为赫兹，也就是一秒钟之内计数器的增量。
|
||
它可以在 <code class="docutils literal notranslate"><span class="pre">config</span></code> 子模块中找到。10ms 的话只需除以常数 <code class="docutils literal notranslate"><span class="pre">TICKS_PER_SEC</span></code> 也就是 100 即可。</p>
|
||
</li>
|
||
</ul>
|
||
<p>后面可能还有一些计时的需求，我们再设计一个函数：</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="c1">// os/src/timer.rs</span>
|
||
|
||
<span class="k">const</span><span class="w"> </span><span class="n">MICRO_PER_SEC</span>: <span class="kt">usize</span> <span class="o">=</span><span class="w"> </span><span class="mi">1_000_000</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">get_time_us</span><span class="p">()</span><span class="w"> </span>-> <span class="kt">usize</span> <span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">time</span>::<span class="n">read</span><span class="p">()</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="p">(</span><span class="n">CLOCK_FREQ</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">MICRO_PER_SEC</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p><code class="docutils literal notranslate"><span class="pre">timer</span></code> 子模块的 <code class="docutils literal notranslate"><span class="pre">get_time_us</span></code> 可以以微秒为单位返回当前计数器的值。</p>
|
||
<p>新增一个系统调用，使应用能获取当前的时间：</p>
|
||
<div class="literal-block-wrapper docutils container" id="id4">
|
||
<div class="code-block-caption"><span class="caption-text">第三章新增系统调用（二）</span><a class="headerlink" href="#id4" title="永久链接至代码">¶</a></div>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="sd">/// 功能：获取当前的时间，保存在 TimeVal 结构体 ts 中，_tz 在我们的实现中忽略</span>
|
||
<span class="sd">/// 返回值：返回是否执行成功，成功则返回 0</span>
|
||
<span class="sd">/// syscall ID：169</span>
|
||
<span class="k">fn</span> <span class="nf">sys_get_time</span><span class="p">(</span><span class="n">ts</span>: <span class="o">*</span><span class="k">mut</span><span class="w"> </span><span class="n">TimeVal</span><span class="p">,</span><span class="w"> </span><span class="n">_tz</span>: <span class="kt">usize</span><span class="p">)</span><span class="w"> </span>-> <span class="kt">isize</span><span class="p">;</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</div>
|
||
<p>结构体 <code class="docutils literal notranslate"><span class="pre">TimeVal</span></code> 的定义如下，内核只需调用 <code class="docutils literal notranslate"><span class="pre">get_time_us</span></code> 即可实现该系统调用。</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="c1">// os/src/syscall/process.rs</span>
|
||
|
||
<span class="cp">#[repr(C)]</span><span class="w"></span>
|
||
<span class="k">pub</span><span class="w"> </span><span class="k">struct</span> <span class="nc">TimeVal</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">pub</span><span class="w"> </span><span class="n">sec</span>: <span class="kt">usize</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">pub</span><span class="w"> </span><span class="n">usec</span>: <span class="kt">usize</span><span class="p">,</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</div>
|
||
<div class="section" id="risc-v">
|
||
<h2>RISC-V 架构中的嵌套中断问题<a class="headerlink" href="#risc-v" title="永久链接至标题">¶</a></h2>
|
||
<p>默认情况下，当 Trap 进入某个特权级之后，在 Trap 处理的过程中同特权级的中断都会被屏蔽。</p>
|
||
<ul class="simple">
|
||
<li><p>当 Trap 发生时，<code class="docutils literal notranslate"><span class="pre">sstatus.sie</span></code> 会被保存在 <code class="docutils literal notranslate"><span class="pre">sstatus.spie</span></code> 字段中，同时 <code class="docutils literal notranslate"><span class="pre">sstatus.sie</span></code> 置零，
|
||
这也就在 Trap 处理的过程中屏蔽了所有 S 特权级的中断；</p></li>
|
||
<li><p>当 Trap 处理完毕 <code class="docutils literal notranslate"><span class="pre">sret</span></code> 的时候， <code class="docutils literal notranslate"><span class="pre">sstatus.sie</span></code> 会恢复到 <code class="docutils literal notranslate"><span class="pre">sstatus.spie</span></code> 内的值。</p></li>
|
||
</ul>
|
||
<p>也就是说，如果不去手动设置 <code class="docutils literal notranslate"><span class="pre">sstatus</span></code> CSR ，在只考虑 S 特权级中断的情况下，是不会出现 <strong>嵌套中断</strong> (Nested Interrupt) 的。</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">注解</p>
|
||
<p><strong>嵌套中断与嵌套 Trap</strong></p>
|
||
<p>嵌套中断可以分为两部分：在处理一个中断的过程中又被同特权级/高特权级中断所打断。默认情况下硬件会避免前一部分，
|
||
也可以通过手动设置来允许前一部分的存在；而从上面介绍的规则可以知道，后一部分则是无论如何设置都不可避免的。</p>
|
||
<p>嵌套 Trap 则是指处理一个 Trap 过程中又再次发生 Trap ，嵌套中断算是嵌套 Trap 的一种。</p>
|
||
</div>
|
||
</div>
|
||
<div class="section" id="id3">
|
||
<h2>抢占式调度<a class="headerlink" href="#id3" title="永久链接至标题">¶</a></h2>
|
||
<p>有了时钟中断和计时器，抢占式调度就很容易实现了：</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="c1">// os/src/trap/mod.rs</span>
|
||
|
||
<span class="k">match</span><span class="w"> </span><span class="n">scause</span><span class="p">.</span><span class="n">cause</span><span class="p">()</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">Trap</span>::<span class="n">Interrupt</span><span class="p">(</span><span class="n">Interrupt</span>::<span class="n">SupervisorTimer</span><span class="p">)</span><span class="w"> </span><span class="o">=></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">set_next_trigger</span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">suspend_current_and_run_next</span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p>我们只需在 <code class="docutils literal notranslate"><span class="pre">trap_handler</span></code> 函数下新增一个分支，触发了 S 特权级时钟中断时，重新设置计时器，
|
||
调用 <code class="docutils literal notranslate"><span class="pre">suspend_current_and_run_next</span></code> 函数暂停当前应用并切换到下一个。</p>
|
||
<p>为了避免 S 特权级时钟中断被屏蔽，我们需要在执行第一个应用前调用 <code class="docutils literal notranslate"><span class="pre">enable_timer_interrupt()</span></code> 设置 <code class="docutils literal notranslate"><span class="pre">sie.stie</span></code>，
|
||
使得 S 特权级时钟中断不会被屏蔽；再设置第一个 10ms 的计时器。</p>
|
||
<div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="linenos"> 1</span><span class="c1">// os/src/main.rs</span>
|
||
<span class="linenos"> 2</span>
|
||
<span class="linenos"> 3</span><span class="cp">#[no_mangle]</span><span class="w"></span>
|
||
<span class="linenos"> 4</span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">rust_main</span><span class="p">()</span><span class="w"> </span>-> <span class="o">!</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="linenos"> 5</span><span class="w"> </span><span class="c1">// ...</span>
|
||
<span class="linenos"> 6</span><span class="w"> </span><span class="n">trap</span>::<span class="n">enable_timer_interrupt</span><span class="p">();</span><span class="w"></span>
|
||
<span class="linenos"> 7</span><span class="w"> </span><span class="n">timer</span>::<span class="n">set_next_trigger</span><span class="p">();</span><span class="w"></span>
|
||
<span class="linenos"> 8</span><span class="w"> </span><span class="c1">// ...</span>
|
||
<span class="linenos"> 9</span><span class="p">}</span><span class="w"></span>
|
||
<span class="linenos">10</span>
|
||
<span class="linenos">11</span><span class="c1">// os/src/trap/mod.rs</span>
|
||
<span class="linenos">12</span>
|
||
<span class="linenos">13</span><span class="k">use</span><span class="w"> </span><span class="n">riscv</span>::<span class="n">register</span>::<span class="n">sie</span><span class="p">;</span><span class="w"></span>
|
||
<span class="linenos">14</span>
|
||
<span class="linenos">15</span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span> <span class="nf">enable_timer_interrupt</span><span class="p">()</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="linenos">16</span><span class="w"> </span><span class="k">unsafe</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">sie</span>::<span class="n">set_stimer</span><span class="p">();</span><span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="linenos">17</span><span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p>就这样，我们实现了时间片轮转任务调度算法。 <code class="docutils literal notranslate"><span class="pre">power</span></code> 系列用户程序可以验证我们取得的成果：这些应用并没有主动 yield，
|
||
内核仍能公平地把时间片分配给它们。</p>
|
||
</div>
|
||
</div>
|
||
|
||
</article>
|
||
<footer>
|
||
|
||
<div class="related-pages">
|
||
<a class="next-page" href="5exercise.html">
|
||
<div class="page-info">
|
||
<div class="context">
|
||
<span>Next</span>
|
||
</div>
|
||
<div class="title">chapter3练习</div>
|
||
</div>
|
||
<svg><use href="#svg-arrow-right"></use></svg>
|
||
</a>
|
||
<a class="prev-page" href="3multiprogramming.html">
|
||
<svg><use href="#svg-arrow-right"></use></svg>
|
||
<div class="page-info">
|
||
<div class="context">
|
||
<span>Previous</span>
|
||
</div>
|
||
|
||
<div class="title">管理多道程序</div>
|
||
|
||
</div>
|
||
</a>
|
||
</div>
|
||
|
||
<div class="related-information">
|
||
Copyright © OS2022Summer
|
||
|
|
||
Built with <a href="https://www.sphinx-doc.org/">Sphinx</a>
|
||
and
|
||
<a class="muted-link" href="https://pradyunsg.me">@pradyunsg</a>'s
|
||
<a href="https://github.com/pradyunsg/furo">Furo theme</a>.
|
||
|
|
||
<a class="muted-link" href="../_sources/chapter3/4time-sharing-system.rst.txt"
|
||
rel="nofollow">
|
||
显示源代码
|
||
</a>
|
||
</div>
|
||
|
||
</footer>
|
||
</div>
|
||
<aside class="toc-drawer">
|
||
|
||
|
||
<div class="toc-sticky toc-scroll">
|
||
<div class="toc-title-container">
|
||
<span class="toc-title">
|
||
目录
|
||
</span>
|
||
</div>
|
||
<div class="toc-tree-container">
|
||
<div class="toc-tree">
|
||
<ul>
|
||
<li><a class="reference internal" href="#">分时多任务系统</a><ul>
|
||
<li><a class="reference internal" href="#id2">时钟中断与计时器</a></li>
|
||
<li><a class="reference internal" href="#risc-v">RISC-V 架构中的嵌套中断问题</a></li>
|
||
<li><a class="reference internal" href="#id3">抢占式调度</a></li>
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
|
||
</div>
|
||
</div>
|
||
</div>
|
||
|
||
|
||
</aside>
|
||
</div>
|
||
</div><script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script>
|
||
<script src="../_static/jquery.js"></script>
|
||
<script src="../_static/underscore.js"></script>
|
||
<script src="../_static/doctools.js"></script>
|
||
<script src="../_static/scripts/main.js"></script>
|
||
<script kind="utterances">
|
||
|
||
var commentsRunWhenDOMLoaded = cb => {
|
||
if (document.readyState != 'loading') {
|
||
cb()
|
||
} else if (document.addEventListener) {
|
||
document.addEventListener('DOMContentLoaded', cb)
|
||
} else {
|
||
document.attachEvent('onreadystatechange', function() {
|
||
if (document.readyState == 'complete') cb()
|
||
})
|
||
}
|
||
}
|
||
|
||
var addUtterances = () => {
|
||
var script = document.createElement("script");
|
||
script.type = "text/javascript";
|
||
script.src = "https://utteranc.es/client.js";
|
||
script.async = "async";
|
||
|
||
script.setAttribute("repo", "LearningOS/rust-based-os-comp2022");
|
||
script.setAttribute("issue-term", "pathname");
|
||
script.setAttribute("theme", "github-light");
|
||
script.setAttribute("label", "comments");
|
||
script.setAttribute("crossorigin", "anonymous");
|
||
|
||
sections = document.querySelectorAll("div.section");
|
||
if (sections !== null) {
|
||
section = sections[sections.length-1];
|
||
section.appendChild(script);
|
||
}
|
||
}
|
||
commentsRunWhenDOMLoaded(addUtterances);
|
||
</script>
|
||
<script src="../_static/translations.js"></script>
|
||
</body>
|
||
</html> |