Modal trains RL models on mixed accelerators with async RL, matching stability at lower cost

AAAzzam · x · 2026-10-14

Modal notes that large-model RL training typically runs on a fixed homogeneous cluster of latest-gen accelerators for numerical stability and throughput — discarding inference optimizations for other vendors/generations, limiting usable capacity, and costing more than needed.

Their approach: train a model on agentic coding tasks using fully asynchronous RL with mixed-precision, mixed-accelerator samplers. With off-policy correction, training stayed stable through convergence, on par with homogeneous samplers, at lower cost.

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