Benjamin Lesage
André Seznec
ABSTRACT
Multithreaded processors, in the context of real-time systems, create the opportunity to mix, on the same hardware platform, the execution of a complex real-time workload and the execution of non-critical applications. But resources sharing, inherent to multithreading, hinders the timing analysis of concurrent tasks. Such analyses are critical to real-time tasks which have timing deadlines that must be met and enforced.
In this paper, we present the PRETI, Partitioned REal-TIme shared cache scheme, a flexible, low implementation-overhead, shared cache partitioning scheme. PRETI can preclude inter-task conflicts on shared caches, and their pessimistic impact on timing estimates, by allocating private cache space to real-time tasks. Therefore, uniprocessor, i.e. unithread, worst-case execution time (WCET) estimation techniques can be used. The remaining cache space, not reserved for currently running real-time tasks, is shared by all tasks running on the processor, in particular the non-critical ones, enabling high performances for these tasks.
Experiments are presented to show that the PRETI cache scheme allows for easing and guaranteeing the schedulability of a set of real-time tasks with tight timing constraints, and enabling high performance for the non-critical tasks.
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Index Terms
- PRETI: partitioned real-time shared cache for mixed-criticality real-time systems
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