System Calls: The Hidden Cost of Performance

This article delves into the performance overhead of Linux system calls, revealing that it's far more than just a simple kernel function call. System calls disrupt CPU microarchitectural optimizations like instruction pipelining and branch prediction, leading to performance losses far exceeding what's apparent in the source code. The article analyzes kernel code, explains the performance impact of various software and hardware mitigations, and offers optimization strategies such as using vDSO, caching values, optimizing I/O, batching operations, and pushing work into the kernel to reduce system call frequency and improve software performance.