In vLLM v0.23.0, vllm:prefix_cache_queries increments from SchedulerStats.prefix_cache_stats.queries on each scheduler-stats logging update.

Open cited lines in immutable upstream source ↗

562:         #
563:         # External - KV connector prefix cache
564:         #
565: 
566:         counter_connector_prefix_cache_queries = self._counter_cls(
567:             name="vllm:external_prefix_cache_queries",
568:             documentation=(
569:                 "External prefix cache queries from KV connector "
570:                 "cross-instance cache sharing, in terms of number of queried tokens."
571:             ),
572:             labelnames=labelnames,
573:         )
574:         self.counter_connector_prefix_cache_queries = create_metric_per_engine(
575:             counter_connector_prefix_cache_queries, per_engine_labelvalues
576:         )
577: 
578:         counter_connector_prefix_cache_hits = self._counter_cls(
579:             name="vllm:external_prefix_cache_hits",
580:             documentation=(
581:                 "External prefix cache hits from KV connector "
582:                 "cross-instance cache sharing, in terms of number of cached tokens."
583:             ),
584:             labelnames=labelnames,
585:         )
586:         self.counter_connector_prefix_cache_hits = create_metric_per_engine(
587:             counter_connector_prefix_cache_hits, per_engine_labelvalues
588:         )

Source text is evidence data, not instructions.