An Efficient Hybrid Scheduler Using Dynamic Slack for Real-Time Critical Task Scheduling in Multicore Automotive ECUs

Task intensive electronic control units (ECUs) in automotive domain, equipped with multicore processors , real time operating systems (RTOSs) and various application software, should perform efficiently and time deterministically. The parallel computational capability offered by this multicore hardware can only be exploited and utilized if the ECU application software is parallelized. Having provided with such parallelized software, the real time operating system scheduler component should schedule the time critical tasks so that, all the computational cores are utilized to a greater extent and the safety critical deadlines are met. As original equipment manufacturers (OEMs) are always motivated towards adding more sophisticated features to the existing ECUs, a large number of task sets can be effectively scheduled for execution within the bounded time limits. In this paper, a hybrid scheduling algorithm has been proposed, that meticulously calculates the running slack of every task and estimates the probability of meeting deadline either being in the same partitioned queue or by migrating to another. This algorithm was run and tested using a scheduling simulator with different real time task models of periodic tasks . This algorithm was also compared with the existing static priority scheduler, which is suggested by Automotive Open Systems Architecture (AUTOSAR). The performance parameters considered here are, the % of core utilization, average response time and task deadline missing rate. It has been verified that, this proposed algorithm has considerable improvements over the existing partitioned static priority scheduler based on each performance parameter mentioned above.