Efficient Reinforcement Learning – Rhythm Garg & Linden Li, Applied Compute
Dec 9, 2025 · 20:19
Rhythm Garg and Linden Li, co-founders of Applied Compute, describe how their company uses efficient reinforcement learning (RL) to specialize large language models for enterprise tasks. They explain that synchronous RL wastes GPU time waiting on straggler samples—99% of arithmetic problems complete in ~40 seconds, but the tail takes 80 more seconds—so they adopt asynchronous pipeline RL. This method dedicates fixed GPUs to sampling and training, allowing continuous inference but introducing stale tokens (up to a tolerated staleness threshold) that require importance ratio corrections. To balance speed and stability, they model the system mathematically: using a roofline-based latency curve for sampling, per-GPU training throughput, and constraints on staleness and KV cache memory. Their simulations, parameterized by response length distributions, reveal an optimal GPU allocation that yields ~60% speedup over synchronous RL while keeping staleness within ML limits. This modeling lets them predict runtime and configure runs without expensive trial-and-error.
