vllm:prefix_cache_queries

Version history

• In vLLM v0.23.0, vllm:prefix_cache_queries is exposed by the V1 PrometheusStatLogger as a Prometheus counter measured in queried tokens, accumulating the tokens presented to the first-party prefix-cache lookup rather than requests or cache blocks.
• In that same version it is registered with the label names model_name and engine.
• Also in v0.23.0, the counter increments from SchedulerStats.prefix_cache_stats.queries on each scheduler-stats logging update and observes first-party prefix-cache token reuse, while KV-connector reuse is reported separately by the vllm:external_prefix_cache_* counters.
• For interpretation in v0.23.0, it serves as the token denominator of a same-label, same-window prefix-cache hit ratio, so it should be combined with prefix_cache_hits using rate or increase over a chosen window instead of reading the cumulative total as a rate.

Identity

Prometheus type

counter

Labels

model_nameengine

Unit

Not recorded — vLLM registration code has no structured unit field, and units are not inferred from name suffixes

Lifecycle

Semantic coverage

Metric knowledge (7)

Related Use Cases (3)

• #12077: Active KV use is not reusable cache residency
• #38194: Prefix-cache percentages require comparable definitions
• #40696: Full-block eligibility creates prefix-cache cliffs

Availability