Mirostat Sampling

Mirostat is a sampling algorithm that targets a fixed perplexity-like "surprise" level (tau) instead of a fixed top-p or top-k. The decoder dynamically tightens or loosens the candidate set at each step to keep the running entropy near tau.

Two variants: Mirostat v1 (the original) and Mirostat v2 (simplified, used by llama.cpp). Both expose tau (target surprise, typical 5.0) and eta (learning rate, typical 0.1).

Some users find Mirostat reduces repetition and produces more coherent long-form generations than top-p alone. Empirically the difference is task-dependent and usually small; top-p with a reasonable repeat penalty handles most cases. Worth knowing because it's a built-in option in llama.cpp/Ollama and shows up in older Reddit threads.