Section: New Results

Real-time analysis

• Scheduling of tasks in automotive multicore ECUs

  Participants: Aurélien Monot, Nicolas Navet, Françoise Simonot-Lion.

  As the demand for computing power is quickly increasing in the automotive domain, car manufacturers and tier-one suppliers are gradually introducing multicore ECUs in their electronic architectures. Additionally, these multicore ECUs offer new features such as higher levels of parallelism which ease the respect of safety requirements such as the ISO 26262 and the implementation of other automotive use-cases. These new features involve also more complexity in the design, development and verification of the software applications. Hence, car manufacturers and suppliers will require new tools and methodologies for deployment and validation. We address the problem of sequencing numerous elementary software components, called runnables, on a limited set of identical cores. We show how this problem can be addressed as two sub-problems, partitioning the set of runnables and building the sequencing of the runnables on each core, which problems cannot be solved optimally due to their algorithmic complexity. We then present low complexity heuristics to partition and build sequencer tasks that execute the runnable set on each core, and derive lower bounds on their efficiency (i.e., competitive ratio). Finally, we address the scheduling problem globally, at the ECU level, by discussing how to extend this approach in the case where other OS tasks are scheduled on the same cores as the sequencer tasks. An article providing a summary of this line of work has been published in IEEE TII [12] .

• Probabilistically analysable real-time system

  Participants: Liliana Cucu-Grosjean, Adriana Gogonel, Codé Lo, Luca Santinelli, Dorin Maxim and Cristian Maxim.

  The adoption of more complex hardware to respond to the increasing demand for computing power in next- generation systems exacerbates some of the limitations of static timing analysis for the estimation of the worst-case execution time (WCET) estimation. In particular, the effort of acquiring (1) detail information on the hardware to develop an accurate model of its execution latency as well as (2) knowledge of the timing behaviour of the program in the presence of varying hardware conditions, such as those dependent on the history of previously executed instructions. These problems are also known as the timing analysis walls. The probabilistic timing analysis, a novel approach to the analysis of the timing behaviour of next-generation real-time embedded systems, provides answers to timing analysis walls. In [10] , [15] we have showed how the probabilistic timing analysis attacks the timing analysis walls. We have also presented experimental evidence that shows how probabilistic timing analysis reduces the extent of knowledge about the execution platform required to produce probabilistically-safe and tight WCET estimations.

  Based on existing estimations of WCET or minimal inter-arrival time, we may propose different probabilistic schedulability analyses [19] , [11] .

• Statistical analysis of real-time systems

  Participants: Liliana Cucu-Grosjean, Adriana Gogonel, Lu Yue, Thomas Nolte [Malardelan University], Rob Davis, Ian Bate [University of York], Michael Houston, Guillem Bernat [Rapita].

  The response time analysis of real-time systems usually needs the knowledge of WCET estimation and this knowledge is not always available, e.g., because of intelectual property issues. This problem may be avoided by estimating statistically either the WCET of a task [18] , the inter-arrival time [17] or the response time of each task [23] .

• Probabilistic Component-based Approaches Participants: Luca Santinelli, Patrick Meumeu Yomsi, Dorin Maxim, Liliana Cucu-Grosjean.

  We have proposed a probabilistic component-based model which abstracts in the interfaces both the functional and non-functional requirements of such systems. This approach allows designers to unify in the same framework probabilistic scheduling techniques and compositional guarantees that go from soft to hard real- time. We have provided sufficient schedulability tests for task systems using such framework when the scheduler is either preemptive fixed-priority or earliest deadline first. These results were published in [16] .