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.
Table of contents
Understanding The Timestamp Counter in the CPUOut of Order Execution and Serializing InstructionsA Complete Example: Measuring Code Execution with RDTSCSummary and Key Takeaways2.5K Impressions