Design Optimization of Mixed-Criticality Real-Time Embedded Systems

Abstract

In this paper we are interested in implementing mixed-criticality real-time embedded applications on a given heterogeneous distributed architecture. Applications have different criticality levels, captured by their Safety-Integrity Level (SIL), and are scheduled using static-cyclic scheduling. According to certification standards, mixed-criticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We consider that the separation is provided by partitioning, such that applications run in separate partitions, and each partition is allocated several time slots on a processor. Tasks of different SILs can share a partition only if they are all elevated to the highest SIL among them. Such elevation leads to increased development costs, which increase dramatically with each SIL. Tasks of higher SILs can be decomposed into redundant structures of lower SIL tasks. We are interested to determine (i) the mapping of tasks to processors, (ii) the assignment of tasks to partitions, (iii) the decomposition of tasks into redundant lower SIL tasks, (iv) the sequence and size of the partition time slots on each processor, and (v) the schedule tables, such that all the applications are schedulable and the development costs are minimized. We have proposed a Tabu Search-based approach to solve this optimization problem. The proposed algorithm has been evaluated using several synthetic and real-life benchmarks.

Una revisión de técnicas para la optimización del despliegue y planificación de sistemas de tiempo real distribuidos

“…El objetivo es cumplir con los plazos de todas las tareas a la vez que se maximiza el tiempo de desuso de las particiones temporales. Posteriormente el trabajo es extendido en (Tȃmaş-Selicean and Pop, 2015), donde se proponen una serie de técnicas para posibilitar la planificación de las aplicaciones, para lo que tiene en cuenta los costes de certificación para albergar aplicaciones de criticidad mixta, que son minimizados empleando distintas técnicas.…”

Architecture exploration for distributed embedded systems: a gap analysis in automotive domain

“…Performance is usually defined in terms of End-to-End (E2E) timing [10]- [14], [26]. Considerations regarding material and development cost can be found in [17], [18], [20], [22], [23].…”

“…Temporal and spacial partitioning techniques are also suggested by the standard to isolate mix criticality tasks on the same ECU. In this way, given the ASILs of all the SW-Cs, DSE methods can also help to decide the allocation of SW-Cs to partitions [22], [23]. Further more, same functions with higher ASIL request much more costly development.…”

“…For example, an ASIL D function can be decomposed into two ASIL B functions or an ASIL C function plus an ASIL A function. Given all the alternative ASIL decomposition strategies and estimated development costs for all the functions with different ASILs, Tǎmaş-Selicean et al [22] proposed a DSE method to also suggest the optimal (in terms of development cost) decomposition of high-ASIL SW-Cs into redundant lower-ASIL SW-Cs. 9) Security: Techniques to improve security can also be considered during the architecting DSE process, such as cryptography [24], [25], run-time intrusion detection [24] and Message authentication codes (MACs) [26].…”

“…For example, reusability [18]- [20] and flexibility [12], [13], [37]. Cost related heuristics have also been considered by DSE methods, such as to reduce the number of ECUs, [17], [18], [20] and ASIL decomposition to reduce verification cost [22], [23].…”