High-Performance Synchronization for User-Level Applications

多处理器系统使用同步原语来协调多个控制线程的活动。尤其是自旋锁在多处理器操作系统和科学应用中得到了广泛的应用。随着多处理器服务器的激增，这些锁也被广泛应用于商业应用中。然而，服务器工作负载的多编程特性要求线程能够“超时”并放弃获取锁的尝试。超时在小型机器上很容易，这些机器可以使用传统的“测试和设置”旋转锁，但这些锁不能扩展到大型机器。主要的替代方案--基于调度器的锁，例如由Java提供的锁--也被证明是令人望而却步的。所提出的研究旨在通过两种主要技术来解决多处理器服务器中用户级同步的代价：(1)在可扩展的基于队列的锁中加入超时；(2)开发用于构造无锁的数据结构的实用机制。这些技术将根据彼此和现有技术进行评估，并将被合并到线程运行时系统中，如Java虚拟机。

Multiprocessor systems use synchronization primitives to coordinate theactivities of multiple threads of control. Spin locks in particular arewidely used in multiprocessor operating systems and in scientificappliactions. With the proliferation of multiprocessor servers, theselocks have come to be widely used in commercial applications as well.The multiprogrammed nature of server workloads, however, requires thatthreads be able to "time out" and abandon an attempt to acquire a lock.Timeout is easy on small machines, which can use traditional"test-and-set" spin locks, but these locks do not scale to largemachines. The principal alternative--scheduler-based locks such asthose provided by Java--has also proven to be prohibitively expensive.The proposed research aims to address the cost of user-levelsynchronization in multiprocessor servers by means of two principaltechniques: (1) the incorporation of timeout in scalable queue-basedlocks, and (2) the development of practical mechanisms for theconstruction of lock-free data structures. These techniques will beevaluated with respect to each other and to existing techniques, andwill be incorporated into threaded run-time systems such as the JavaVirtual Machine.