An algorithm for deciding minimal cache sizes in real-time systems

Abstract

When designing real-time systems, predictability is of utmost importance. A locking cache is a cache memory that allows loading and locking instructions, thus avoiding their replacement. This way, regarding memory accesses, execution time of instructions is constant since it does not depend on the sequence of memory references. With a predictable behaviour, locking cache memories are a practical alternative to conventional caches for real-time systems. Offering similar performance to conventional caches, locking caches allow an accurate yet simple schedulability analysis.Locking caches may also help to reduce the size of a system, by means of reducing cache size. When reducing cache size, also cost and power consumption may be reduced. This way, both predictability and cost saving is provided by means of locking cache.This work presents a set of algorithms, aimed to select the contents of a locking cache that provides the minimum locking cache size, while the system remains schedulable. Compared to a previous approach, the algorithms presented in this paper are able to select a set of main memory blocks that result in a smaller cache size

Combining watchdog processor with instruction cache locking for a fault-tolerant, predictable architecture applied to fixed-priority, preemptive, multitasking real-time systems

“…Experiments are carried out using the real-time systems presented in [10]. In this set of systems there are 14 different task sets.…”

“…In this work a modified version of the genetic algorithm presented in [10] is used. There are two main modifications to this algorithm.…”

Using Dynamic, Full Cache Locking and Genetic Algorithms for Cache Size Minimization in Multitasking, Preemptive, Real-Time Systems

“…In [9] a new version of a genetic algorithm is proposed. The target of this algorithm is not to improve system performance but to reduce the size of the cache memory needed to get an schedulable real-time system.…”

“…In order to study the ability to reduce the cache size the real-time systems presented in [9] were used. In this set of systems there are 14 different task sets.…”