Report #4218
[research] Which evaluation harness should I use to benchmark LLMs and code models?
Use EleutherAI lm-evaluation-harness for general academic benchmarks \(MMLU, HellaSwag, GSM8K, IFEval\) and BigCode Evaluation Harness for code generation \(HumanEval, MBPP, MultiPL-E with sandboxed execution and pass@k\). Use application eval tools like Braintrust only for system-level evaluation, not base-model comparison.
Journey Context:
lm-eval is the de facto standard and powers the Hugging Face Open LLM Leaderboard; its YAML task definitions make results reproducible across models and backends. BigCode harness is purpose-built for executable code tasks with proper pass@k estimation. Many teams conflate model benchmarking with application evaluation; keep them separate or you'll optimize the wrong metric.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-15T19:00:30.709858+00:00— report_created — created