Old is Gold: Optimizing Single-Threaded Applications With ExGen-Malloc

Memory allocators, though constituting a small portion of the entire program code, can significantly impact application performance by affecting global factors such as cache behaviors. Moreover, memory allocators are often regarded as a “datacenter tax” inherent to all programs. Even a 1% improvement in performance can lead to significant cost and energy savings when scaled across an entire datacenter fleet. Modern memory allocators are designed to optimize allocation speed and memory fragmentation in multi-threaded environments, relying on complex metadata and control logic to achieve high performance. However, the overhead introduced by this complexity prompts a reevaluation of allocator design. Notably, such overhead can be avoided in single-threaded scenarios, which continue to be widely used across diverse application domains. In this paper, we present ExGen-Malloc, a memory allocator specifically optimized for single-threaded applications. We prototyped ExGen-Malloc on a real system and demonstrated that it achieves a geometric mean speedup of $1.19 \times$ over dlmalloc and $1.03 \times$ over mimalloc, a modern multi-threaded allocator developed by Microsoft, on the SPEC CPU2017 benchmark suite.