Balance Sparse Mixture-of-Experts Routing Under Capacity Limits
A sparse mixture-of-experts layer does not send every token through every parameter block. A router scores the available experts, selects a small subset for each token, and dispatches token representations only to those selected experts. That conditional computation is the main attraction of sparse MoE designs, but it also creates a resource-allocation problem inside the model. The router can prefer the same experts for many tokens. Hardware, meanwhile, has finite buffers and communication capacity. A routing policy that looks reasonable from token scores alone can therefore create overloaded experts, idle experts, uneven communication, or discarded assignments.