Mixed Time-Criticality Process Interferences Characterization on a Multicore Linux System

The increasing interest in the integration of Mixed Criticality Systems (MCS) in Commercial-Off-The-Shelf (COTS) platforms leads to an increasing number of challenges. The possibility of sharing computing resources among applications with different time criticalities is a key goal for COTS systems, but still hard to achieve. Classical approaches in real-time systems are not feasible when platform and operating system may introduce unpredictability in the task execution. Moreover, if the system must also meet non-functional requirements (e.g., thermal and power management), dynamic approaches of computing resources allocation are more effective than static ones. Unfortunately, this contributes to increasing the complexity of the scenario. In MCS, the overheads and the unpredictability caused by sharing resources like cache memories have been well studied. However, in some cases we could also consider the operating system itself as a potential source of unexpected and unpredictable latencies, if several running tasks perform system calls. This work aims at proposing a model for the intra-core and inter-core interferences and the analysis of the OS-induced latencies in a Linux real-time system, both essential for the creation of smart and effective run-time resource management policies.