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<ol class="chapter"><li class="chapter-item expanded affix "><a href="index.html">简明 zCore 教程</a></li><li class="chapter-item expanded affix "><a href="zcore-intro.html">🚧 zCore 整体结构和设计模式</a></li><li class="chapter-item expanded affix "><a href="fuchsia.html">🚧 Fuchsia OS 和 Zircon 微内核</a></li><li class="chapter-item expanded "><a href="ch01-00-object.html"><strong aria-hidden="true">1.</strong> 内核对象</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch01-01-kernel-object.html"><strong aria-hidden="true">1.1.</strong> ✅ 初识内核对象</a></li><li class="chapter-item expanded "><a href="ch01-02-process-object.html"><strong aria-hidden="true">1.2.</strong> 🚧 对象管理器：Process 对象</a></li><li class="chapter-item expanded "><a href="ch01-03-channel-object.html"><strong aria-hidden="true">1.3.</strong> 🚧 对象传送器：Channel 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch02-00-task.html"><strong aria-hidden="true">2.</strong> 任务管理</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch02-01-zircon-task.html"><strong aria-hidden="true">2.1.</strong> 🚧 Zircon 任务管理体系</a></li><li class="chapter-item expanded "><a href="ch02-02-process-job-object.html"><strong aria-hidden="true">2.2.</strong> 🚧 进程管理：Process 与 Job 对象</a></li><li class="chapter-item expanded "><a href="ch02-03-thread-object.html"><strong aria-hidden="true">2.3.</strong> 🚧 线程管理：Thread 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch03-00-memory.html"><strong aria-hidden="true">3.</strong> 内存管理</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch03-01-zircon-memory.html"><strong aria-hidden="true">3.1.</strong> 🚧 Zircon 内存管理模型</a></li><li class="chapter-item expanded "><a href="ch03-02-vmo.html"><strong aria-hidden="true">3.2.</strong> 🚧 物理内存：VMO 对象</a></li><li class="chapter-item expanded "><a href="ch03-03-vmo-paged.html"><strong aria-hidden="true">3.3.</strong> 🚧 物理内存：按页分配的 VMO</a></li><li class="chapter-item expanded "><a href="ch03-04-vmar.html"><strong aria-hidden="true">3.4.</strong> 🚧 虚拟内存：VMAR 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch04-00-userspace.html"><strong aria-hidden="true">4.</strong> 用户程序</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch04-01-user-program.html"><strong aria-hidden="true">4.1.</strong> 🚧 Zircon 用户程序</a></li><li class="chapter-item expanded "><a href="ch04-02-context-switch.html"><strong aria-hidden="true">4.2.</strong> 🚧 上下文切换</a></li><li class="chapter-item expanded "><a href="ch04-03-syscall.html"><strong aria-hidden="true">4.3.</strong> 🚧 系统调用</a></li></ol></li><li class="chapter-item expanded "><a href="ch05-00-signal-and-waiting.html"><strong aria-hidden="true">5.</strong> 信号和等待</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch05-01-wait-signal.html"><strong aria-hidden="true">5.1.</strong> 🚧 等待内核对象的信号</a></li><li class="chapter-item expanded "><a href="ch05-02-port-object.html"><strong aria-hidden="true">5.2.</strong> 🚧 同时等待多个信号：Port 对象</a></li><li class="chapter-item expanded "><a href="ch05-03-more-signal-objects.html"><strong aria-hidden="true">5.3.</strong> 🚧 实现更多：EventPair, Timer 对象</a></li><li class="chapter-item expanded "><a href="ch05-04-futex-object.html" class="active"><strong aria-hidden="true">5.4.</strong> 🚧 用户态同步互斥：Futex 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch06-00-hal.html"><strong aria-hidden="true">6.</strong> 硬件抽象层</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch06-01-zcore-hal-unix.html"><strong aria-hidden="true">6.1.</strong> ✅ UNIX硬件抽象层</a></li></ol></li></ol> </div>
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<h1 id="用户态同步互斥futex-对象"><a class="header" href="#用户态同步互斥futex-对象">用户态同步互斥：Futex 对象</a></h1>
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<h2 id="futex-机制简介"><a class="header" href="#futex-机制简介">Futex 机制简介</a></h2>
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<blockquote>
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<p>Futex 是现代 OS 中用户态同步互斥的唯一底层设施</p>
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<p>为什么快：利用共享内存中的原子变量，避免进入内核</p>
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</blockquote>
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<p>Futexes 是内核原语，与用户空间原子操作一起使用以实现高效的同步原语（如Mutexes， Condition Variables等），它只需要在竞争情况（contended case）下才进行系统调用。通常它们实现在标准库中。</p>
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<p>实现 wait 和 wake 函数，并做单元测试</p>
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<p>实现 Zircon 中定义的复杂 API</p>
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