DriftBench: Measuring and Predicting Infrastructure Drift in LLM Serving Systems
DriftBench is a measurement and prediction framework comprising 236,985 prompt-response pairs across 105 configurations, 5 models, 4 GPU platforms, 3 frameworks, and 3 precisions. Its Portability Risk Index generalizes to unseen hardware (R² = 0.909) and precision (R² = 0.763), separating systematic hardware/precision drift from framework/model changes that require re-measurement. In production validation, it blocked a high-drift upgrade where 23.85% of safety prompts flipped classification.