Technical Guide to System Calls: Implementation and Signal Handling in Modern OS

Table of Contents Introduction System calls are fundamental interfaces between user applications and the operating system kernel. They allow programs to request services from the operating system, such as file operations, process control, and network access. One important distinction in system calls is between “fast” and “slow” system calls, which affects how they interact with signal handling, process scheduling, and overall system performance. In this article, we’ll explore: The core differences between fast and slow system calls The mechanism behind how signals can wake up blocked system calls Practical examples with code demonstrations How the kernel handles these different types of system calls Core Definitions: Fast vs. Slow System Calls Fast System Calls Fast system calls are operations that can be completed immediately without requiring the kernel to wait for external events. They typically: Return quickly, usually within microseconds Don’t require the calling proce ... Read full article.