Predictable multithreading of embedded applications using PRET-C

Abstract

We propose a new language called Precision Timed C (PRET-C), for predictable and lightweight multithreading in C. PRET-C supports synchronous concurrency, preemption, and a high-level construct for logical time. In contrast to existing synchronous languages, PRET-C offers C-based shared memory communications between concurrent threads that is guaranteed to be thread safe. Due to the proposed synchronous semantics, the mapping of logical time to physical time can be achieved much more easily than with plain C, thanks to a Worst Case Reaction Time (WCRT) analyzer (not presented here). Associated to the PRET-C programming language, we present a dedicated target architecture, called ARPRET, which combines a hardware accelerator associated to an existing softcore processor. This allows us to improve the throughput while preserving the predictability. With extensive benchmarking, we then demonstrate that ARPRET not only achieves completely predictable execution of PRET-C programs, but also improves the throughput when compared to the pure software execution of PRET-C. The PRET-C software approach is also significantly more efficient in comparison to two other lightweight concurrent C variants (namely SC and Protothreads), as well as the well-known Esterel synchronous programming language.

Using C language extensions for developing embedded software: a case study

“…Our SMT study shows that developers actually use this extension possibility. Macros In today's practice, macro libraries such as Protothreads [10], SynchronousC [58] and PRET-C [42] are are used extensively. Macros are resolved during compilation and hence incur no performance penalty, but they have draw- 17 http://www.mathworks.com/products/stateflow/ backs.…”

ILPc: A novel approach for scalable timing analysis of synchronous programs

“…• We extend the conventional ILP technique for SCFG to model TCCFG [3]. Our approach directly models the semantics of synchronous programs: logical ticks, concurrent threads, and preemptions.…”

A PRET microarchitecture implementation with repeatable timing and competitive performance

“…Andalam et al [11] propose the Auckland Reactive PRET (ARPRET), designed to execute compiled PRET-C programs. PRET-C is a C extension (via macros), with certain restrictions, supporting synchronous concurrency and high-level constructs for expressing logical time.…”