Explain the difference between expert-level and device-...

Expert-level balancing uses the fi * Pi structure to penalize routing concentration at the individual expert level, ensuring that all experts are utilized. Device-level balancing applies a similar Fd * Pd structure at the GPU level to prevent network congestion. These two objectives are distinct and can conflict; for example, you might have balanced expert usage, but if all the most frequently used experts are hosted on the same GPU, you will still experience device-level communication bottlenecks.