Friday, October 3, 2014 at 12:33 am
Real time is all about providing a result in a bounded amount of time. It is about juggling multiple inputs from the outside world and supplying outputs back to it exactly when needed. An example of a real-time application is the antilock brakes on your car (they must be accurately pulsed tens of times per second). To satisfy the needs of real-time systems, APIs must be available to support accurate timing, fast communications and I/O, and precise, priority-driven scheduling. Conventional wisdom held that without proprietary APIs and OSes, it was impossible to achieve the level of performance required to solve real-time problems. However, there are significant costs associated with coding solutions to a proprietary product.
Recognizing this, OS vendors, researchers, and users participated in an IEEE working group known as Posix.4. The group’s goal was to refine existing Posix APIs and develop new APIs to address the needs of the real-time environment. The result of this effort was the Posix 1003.1b-1993 standard,…