Modal trains RL models on mixed-accelerator clusters, matching homogeneous setups at lower cost

charles_irl · x · 2026-10-14

Modal challenges the norm that RL training requires a homogeneous cluster of the latest accelerators, calling big homogeneous clusters "a sledgehammer for an inference-shaped nail." Using fully asynchronous RL with mixed-precision, mixed-accelerator samplers plus off-policy correction on agentic coding tasks, training stayed stable through convergence — on par with homogeneous samplers at lower cost. A reason to rethink RL compute procurement.

Related event: Modal Shows Heterogeneous Accelerators Can Train RL Cheaper Without Losing Stability(4 posts)→

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