A PRET architecture supporting concurrent programs with composable timing properties

In order to improve design time and efficiency of systems, large scale system design is often split into the design of separate functions, which are later integrated together. For real time safety critical applications, the ability to separately verify timing properties of functions is important. If the integration of functions on a particular platform destroys the timing properties of individual functions, then it is not possible to verify timing properties separately. Modern computer architectures introduce timing interference between functions due to unrestricted access of shared hardware resources, such as pipelines and caches. Thus, it is difficult, if not impossible, to integrate two functions on a modern computer architecture while preserving their separate timing properties. This paper describes a realization of PRET, a class of computer architectures designed for timing predictability. Our realization employs a thread-interleaved pipeline with scratchpad memories, and has a predictable DRAM controller. It decouples execution of multiple hardware contexts on a shared hardware platform, which allows for a straight forward integration of different functions onto a shared platform.