Inter-task cache interference aware partitioned real-time scheduling

With the increasing number of cores in processors, shared resources like caches are interfering task execution behaviours more heavily and often render global scheduling approaches infeasible in practice. While partitioned scheduling alleviates such interference, in most existing partitioned approaches, constant WCET, which potentially includes all possible interference, must be statically pre-determined prior to the partitioning processes. In this paper, we show that by taking inter-task interference into consideration when making scheduling decisions, resource efficiency can be significantly improved in both temporal and spatial domains for multi/many-core real-time systems. In particular, we propose the inter-task interference matrix (ITIM) to model the inter-task cache/memory interference in a pair-wise manner. Focusing on the problem of interference-aware partitioned scheduling with ITIM, we formalize it as a mixed integer linear program (MILP), which can be solved to achieve optimal solution at the cost of high computational complexity. Meanwhile, we also provide several polynomial-time algorithms to solve the problem approximately. We extensively profile a set of WCET benchmark programs on x86-based multiprocessor server to collect ITIM. The algorithms are evaluated comprehensively, and the evaluation results demonstrate the superior performance of the proposed approaches under various settings.