vLLM precision gap prevents GRPO convergence
SergioPaniego · x · 2026-08-20
A technical finding shows that vLLM generating in bf16 while the trainer computes in fp32 stops GRPO from converging even on trivial tasks. The precision gap silently pushes tokens past PPO's clipping boundary, causing gradients to vanish. Matching precisions resulted in 5.8x better policy updates per step.
More from Infra
- Baby's first PC: 3090 with local LLM inference — QuixiAI · 2026-08-20
- SK hynix preps for post-HBM era with 3D stacking shift — zephyr_z9 · 2026-08-20
- Guangdong, Alibaba Sign Strategic Pact to Boost AI, Chips and Computing Power — pstAsiatech · 2026-08-20
- GPU Market Pricing Chaos: Spreads Wide Across Venues — AccBalanced · 2026-08-20
- Dual RTX 3090 running Qwen3.8-27B locally at 50-65 tok/s — is that normal? — sugarfreecaffeine · 2026-08-20
- AVX-512 Deemed Superior to ARM SVE: Register & Masking Edge — lemire · 2026-08-20