A Predictable QoS-aware Memory Request Scheduler for Soft Real-time Systems

A memory controller manages the flow of data to and from attached memory devices. The order in which a set of contending memory requests from different tasks are serviced significantly influences the rate of progress and completion times of these tasks. This in turn may affect the Quality-of-Service (QoS) delivered by these tasks. In this article, we focus towards the design of a QoS-aware memory controller targeted towards soft real-time systems. The proposed memory controller tries to generate an urgency-based schedule for the contending memory requests based on the allowable response time latencies associated with each request. The objective is to improve task-level response time predictability while maximizing acquired QoS. Exhaustive experiments carried out using real memory traces and standard simulation tools exhibit the practical efficacy of the proposed memory controller design.