Abstract

Modern Advanced Driver-Assistance Systems (ADAS) combine critical real-time and non-critical best-effort tasks and messages onto an integrated multi-core multi-SoC hardware platform. The real-time safety-critical software tasks have complex interdependencies in the form of end-to-end latency chains featuring, e.g., sensing, processing/sensor fusion, and actuating. The underlying real-time operating systems running on top of the multi-core platform use static cyclic scheduling for the software tasks, while the communication backbone is either realized through PCIe or Time-Sensitive Networking (TSN). In this paper, we address the problem of configuring ADAS platforms for automotive applications, which means deciding the mapping of tasks to processing cores and the scheduling of tasks and messages. Time-critical messages are transmitted in a scheduled manner via the timed-gate mechanism described in IEEE 802.1Qbv according to the pre-computed Gate Control List (GCL) schedule. We study the computation of the assignment of tasks to the available platform CPUs/cores, the static schedule tables for the real-time tasks, as well as the GCLs, such that task and message deadlines, as well as end-to-end task chain latencies, are satisfied. This is an intractable combinatorial optimization problem. As the ADAS platforms and applications become increasingly complex, such problems cannot be optimally solved and require problem-specific heuristics or metaheuristics to determine good quality feasible solutions in a reasonable time. We propose two metaheuristic solutions, a Genetic Algorithm (GA) and one based on Simulated Annealing (SA), both creating static schedule tables for tasks by simulating Earliest Deadline First (EDF) dispatching with different task deadlines and offsets. Furthermore, we use a List Scheduling-based heuristic to create the GCLs in platforms featuring a TSN backbone. We evaluate the proposed solution with real-world and synthetic test cases scaled to fit the future requirements of ADAS systems. The results show that our heuristic strategy can find correct solutions that meet the complex timing and dependency constraints at a higher rate than the related work approaches, i.e., the jitter constraints are satisfied in over 6 times more cases, and the task chain constraints are satisfied in 41% more cases on average. Our method scales well with the growing trend of ADAS platforms.

Highlights

  • Advanced Driver Assistance Systems (ADAS), present in more and more modern consumer vehicles, perform complex functions that range from driver assistance, e.g., automated or assisted parking, lane changing, etc., to fully autonomous driving

  • In our earlier work (McLean et al, 2020) we considered that the communication backbone is done via Peripheral Component Interconnect Express (PCIe), and we have used a periodic real-time task model in which the worst-case execution time (WCET) of a task changes based on the core speed and the communication is modeled as overhead at the end of task instance execution

  • All experiments were conducted on a High Performance Computing (HPC) cluster, with each node configured with 2xIntel Xeon Processor 2660v3 (10 cores, 2.60 GHz) and 128 GB memory

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Summary

INTRODUCTION

Advanced Driver Assistance Systems (ADAS), present in more and more modern consumer vehicles, perform complex functions that range from driver assistance, e.g., automated or assisted parking, lane changing, etc., to fully autonomous driving. In modern ADAS systems, there is a drive towards moving functions from hardware to software and the architecture from distributed to centralized, allowing modularization within an integrated hardware platform that can be cooperatively used and centrally managed (Niedrist, 2018) This drive has multiple advantages, like reusability and portability, but presents several challenges, especially in terms of real-time, testing, and safety (Gietelink et al, 2006). Integrated ADAS platforms are composed of heterogeneous multi-core CPUs and Systems-on-chip (SoCs) of different performance and safety levels that are interlinked by a (real-time) communication network (Sommer et al, 2013; Becker et al, 2016b) In such integrated platforms, the ADAS functions have complex timing requirements and feature a complex interdependence between sensors, control software, and actuators. Other less critical systems, like infotainment, are integrated into the same platform and must not interfere with the real-time behavior of critical functions

Related Work
Contributions
System Model
Application Model
Timing Constraints
PROBLEM FORMULATION
MAPPING AND SCHEDULING STRATEGY
Solution Overview and Cost Function
Metaheuristics
Joint Flow and Task Scheduling
Lower Bound
EDF Simulation for Schedule Synthesis
EXPERIMENTAL RESULTS
Experimental Results for PCIe-Based Systems
Experimental Results for TSN-Based Systems
CONCLUSION AND FUTURE WORK
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