kv pressure

Unlike a training job, a slow serving replica holds nobody else back, so it survives unnoticed while degrading a slice of users. The five causes and the metric that distinguishes each, why routing can create the symptom with no hardware fault, and the fix that limits damage while you investigate.

Admission, a step that grows every sequence, and preemption under memory pressure. The loop is short and it has a failure that only appears when the cache is tight: in a measured run it preempted seventeen times and completed nothing, because every preempted sequence restarted from zero.