The primary objective of a feedback loop is to minimize the —the difference between a desired state ( Setpoint ) and the actual state ( Measured Output ). Setpoint (
): The target value (e.g., a 95% cache hit rate or 200ms latency). Controller ( Feedback Control for Computer Systems
): The algorithm that calculates what change to apply based on the error. Control Input ( The primary objective of a feedback loop is
Feedback control for computer systems applies classical control theory—originally used for physical systems like engines—to digital environments like web servers, databases, and caches. It enables systems to self-adjust to maintain performance goals despite unpredictable workloads or resource shifts. ⚙️ Core Concepts of Feedback Control Control Input ( Feedback control for computer systems
The controller is the most common algorithm used to close the feedback loop. Feedback Control for Computer Systems [Book] - O'Reilly
): The lever the controller pulls (e.g., scaling server instances or adjusting cache size). The computer process being managed. Measured Output ( ): The actual current performance metric. 🛠️ The PID Controller: The Standard Algorithm