Liangxu Linux

Sep 2, 2020 · Fundamentals

Why System Calls Are So Expensive: From INT 0x80 to vDSO

This article explains how Linux system calls work, compares their overhead to regular function calls, and details the three implementation methods—software interrupts, fast syscall instructions, and the virtual dynamic shared object (vDSO)—including their performance trade‑offs and practical usage.