Mutual exclusion is an important problem in the context of shared resource usage, where only one process can be using the shared resource at any given time. A mutual exclusion protocol that does not use information on the duration for which each process uses the resource can lead to sub-optimal utilization times. We consider a simple two-process mutual exclusion problem with a central server that provides access to the shared resource. We show that even in the absence of a clock, under certain conditions, the server can opportunistically grant early access to a client based on timing information. We call our new protocol opportunistic mutual exclusion. Our approach requires an extra request signal on each channel between client and server to convey extra information, and the server can grant early access based only on the order of events rather than through measuring time. We derive the handshaking specification and production rules for our protocol, and report on the energy and delay of the circuits in a 65nm process.

翻译：互斥是共享资源使用场景中的一个重要问题，其中任意时刻只能有一个进程使用共享资源。不利用各进程资源使用时长信息的互斥协议可能导致资源利用率低。本文考虑一个简单的两进程互斥问题，其中中央服务器负责提供共享资源的访问权限。我们证明，即使在没有时钟的情况下，满足特定条件时，服务器也能基于时序信息机会性地提前授予客户端访问权限。我们将这种新协议称为"机会互斥"。该方法要求在客户端与服务器之间的每个通道上增加一个额外请求信号来传递附加信息，且服务器仅依据事件顺序而非时间测量来提前授予访问权限。我们推导了该协议的握手规范与产生式规则，并报告了在65nm工艺下电路的能耗与延迟特性。