Real-Time, Execution-time variability, Adaptive systems, WCET analysis, Schedulability analysis, Synchronous Languages
In real-time safety critical domains (such as avionics, automotive, train control, etc.), it is of paramount importance to guarantee that computation is performed within certain time bounds. To guarantee correctness, the designer needs first to compute bounds on the execution time of every block of code, and then to guarantee that every block will be scheduled by the Operating System before its deadline.
Today, it is difficult to build efficient and predictable real-time systems on modern processors, because even a simple piece of code exhibits a large execution time variability. Therefore, the designer needs to greatly over-provision the computational capacity of the processors. While some methods have been proposed to deal with such large variations, they are not immediately applicable because they focus on scheduling without considering the functional aspects of the application.
The overall objective of this project is to contribute to the design and development of the next generation of safety critical embedded real-time systems. In particular, we aim at solving the problem of the large variability of execution times by using sound and provably correct programming models that combine functional and timing aspects.
The main ideas of the project can be summarized as follows:
- We will use parametric Worst-Case Execution Time (WCET) analysis techniques for computing off-line a WCET formula. The formula is parametrized with respect to elements such as the input values of the code block or the state of the processor cache;
- We plan to use the formula at run-time to estimate a tighter WCET bound dynamically;
- Based on this estimate we will dynamically adapt the application behaviour so as to avoid deadline misses;
- The designer will specify the possible adaptations of the system by using a synchronous language to formally guarantee at the same time functional and timing correctness;
- We propose to use a design methodology to help the designer configure the system in the best way.
A more detailed presentation of the project is available in the public version of the submission made to the 2017 ANR call.
Corteva relies on the expertise of its partner and reuses some of their previous work, namely: