Function llm_worker_rss_mb 

pub fn llm_worker_rss_mb() -> u64

Per-worker RSS budget in MiB: XDG llm.worker_rss_mb or LLM_WORKER_RSS_MB.

The knob exists because the default is an estimate and not a measurement (see LLM_WORKER_RSS_MB). 0 is rejected in favour of the default: a zero budget would make every available_mb / per_worker division either panic or authorise unbounded concurrency.