Hugging Face Daily PapersMobina Kashaniyan, Ali Jannesari2 min readpaperintermediate
Sample Count Is Not Enough: Candidate-Generation Strategy Shapes the Energy and Performance of LLM Test-Time Scaling
Summary
Increasing the number of LLM candidates (N) improves reasoning accuracy, but the way those candidates are generated (batch size vs sequential calls) dramatically affects latency, GPU‑hours, and energy. On A100 GPUs, eight serial 1‑candidate calls consume ~5× more energy and take ~6× longer than a single 8‑candidate batched call, even though total candidate count is identical. The authors recommen…
- Accuracy gains from test‑time scaling are tied to total candidate count (e.g., N=8 gives +8.4 pp on Phi‑3‑mini, +18.4 pp on Qwen2.5‑1.5B on GSM8K).
- Generation schedule matters: 1×8 (one batched call) vs 8×1 (eight serial calls) shows 4.6‑4.9× higher GPU‑device energy and 5.8‑6.1× higher P95 latency for the serial case.
- Results are consistent across models, GPU types (A100, V100), and datasets (GSM8K, SciQ).
- When memory permits, fewer calls with larger batch sizes are far more efficient for multi‑candidate inference.
LLM inference cost is a primary bottleneck for production services. This work shows that naïvely reporting only the number of generated candidates hides large variations in hardware usage and latency, which directly impact cloud spend and user experience. Engineers can immediately reduce inference…
6/10
