Mixture of experts: sparse work, uneven traffic

Picture it

Imagine a sprawling university where instead of one omniscient professor, you have a panel of hyper-specialized experts. When a question is asked, a router swiftly points it to only the two experts who actually know the answer, while the rest stay silent. This sparse activation saves an immense amount of mental energy per question, but you still need a massive auditorium to house all the experts, and sudden crowds around one popular expert can cause frustrating traffic jams.

What to understand

• Total versus active parameters, expert parallelism, all-to-all
• Hot experts, load balance, token dispatch, and communication overlap

Follow the references

1. 1 · Paper

   Jiang et al. · Mixtral of Experts ↗

   Read the architecture and active-parameter explanation.

2. 2 · Documentation

   vLLM · Expert parallel deployment ↗

   Study expert placement and load-balancing options for the deployed backend.

Make it concrete

Trace tokens per expert and dispatch time under two input domains. Compare balanced and skewed traffic; record tail latency and idle devices.