Experience with a Prototype of the POSIX "Minimal Realtime System Profile"

This paper describes experience prototyping the proposed IEEE standard "minimal realtime system profile ", whose primary component is support for realtime threads. It provides some background, describes the implementation, and reports preliminary performance measurements. 1 Introduction A thread is an independent sequential flow of control. Threads differ from processes by sharing a common virtual address space with other threads. Threads are widely accepted as a computational building block for both uniprocessor and multiprocessor environments. In uniprocessor environments, the thread model simplifies the programming of asynchronous operations. In multiprocessor environments, threads may also allow higher throughput, by utilizing more than one processor. The idea of cheap concurrency or "lightweight processes " has been around in various forms for a long time, including support for coroutines in the Mesa programming language[13], and multitasking in the Ada programming language[18]...