RT-Mimalloc: A New Look at Dynamic Memory Allocation for Real-Time Systems

Dynamic memory allocation is a pivotal feature of modern software systems but has mostly been scarcely used in real-time systems due to the limited time-predictability offered by dynamic memory allocators (DynMAs). While many general-purpose DynMAs have been proposed during the last decades, only a few efforts were devoted to the design of real-time DynMAs capable of providing bounded allocation times. Furthermore, the most notable of them dates back to almost 20 years ago. Motivated by this observation and the significant developments made in the field of general-purpose DynMAs in recent years, this work takes a new look at dynamic memory allocation for real-time systems. After analyzing and comparing modern DynMAs, we discuss how to modify the Mimalloc general-purpose DynMA into RT-Mimalloc, so that more predictable allocation times can be obtained. All the studies and evaluations performed in this work were based on both modern state-of-the-art benchmarks for memory allocation and synthetic workload to assess specific capabilities of the tested DynMAs. The evaluation showed that RT-Mimalloc is capable to improve the longest-observed allocation times of real-time DynMAs proposed in previous work while retaining most of the benefits of modern general-purpose DynMAs in terms of average-case performance.