wfspan: Wait-free Dynamic Memory Management

Abstract

Dynamic memory allocation plays a vital role in modern application programs. Modern lock-free memory allocators based on hardware atomic primitives usually provide good performance. However, threads may starve in these lock-free implementations, leading to unbounded worst-case execution time that is not allowed in real-time embedded systems. This article presents decentralized dynamic memory management, wfspan, based on non-linearizable wait-free lists. It employs a helping mechanism to ensure no starvation in the lock-free implementation. From the perspective of design tradeoff, wfspan guarantees bounded execution steps in both allocation and deallocation procedure, at the cost of increasing bounded worst-case memory footprint. The results of running benchmarks on an x86/64 and an aarch64 machine illustrate that wfspan achieves competitive performance and memory footprint compared to lock-based and lock-free practical memory allocators while showing superior to other allocators in terms of worst-case execution time.