A deep dive into rdtsc, instruction stream serialization, and memory fences for precise cycle-level performance measurement.

Code Confessions is a platform or blog where developers share their experiences, challenges, and insights from their journey in software development. Through personal anecdotes, lessons learned, and reflections on coding practices, Code Confessions offers a candid and relatable perspective on the joys and struggles of being a programmer. Readers can find inspiration, empathy, and  lessons from the stories shared by fellow developers.

Confessions of a Code Addict

Learn how to use the x86 RDTSC instruction for precise cycle-level performance measurement. The guide explains the CPU's timestamp counter, challenges of out-of-order execution, and how to use serializing instructions (cpuid) and memory fences (lfence, sfence, mfence) to obtain accurate benchmarks. Includes practical code examples demonstrating proper RDTSC usage with rdtscp, handling core migration, and avoiding common pitfalls when measuring code that executes in hundreds of cycles.

A Systems Engineer’s Guide to Benchmarking with RDTSC

Understanding The Timestamp Counter in the CPU

Out of Order Execution and Serializing Instructions

A Complete Example: Measuring Code Execution with RDTSC