vllm:time_to_first_token_seconds

Histogram of time to first token in seconds.

MetricPrometheusvLLM v0.23.0verified 10 hr ago

Identity

Prometheus type: histogram
Labels: model_nameengine
Buckets: 22 boundaries · 0.001 → 2560
Unit: Not recorded — vLLM registration code has no structured unit field, and units are not inferred from name suffixes

Semantic coverage

covered · Availability & namecovered · Structural identitycovered · Measurement semanticscovered · Causal/runtime semanticscovered · Interpretation & compositioncovered · Guarded guidance

Metric knowledge (7)

Claim	Semantic layer	Verified
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` observes elapsed seconds from request arrival to the first produced token.	Measurement semantics	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` adds an observation when iteration processing identifies the request as prefilling/producing its first token.	Causal/runtime semantics	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` its histogram count follows first-token events and need not equal a finished-request counter across abort and error paths.	Interpretation & composition	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` use histogram quantiles with matched labels and windows; reconcile lifecycle population before comparing its count with `request_success`.	Guarded guidance	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` is registered as a Prometheus histogram.	Structural identity	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` is registered with the label names `model_name`, engine.	Structural identity	10 hr ago
In vLLM v0.23.0, `vllm:time_to_first_token_seconds` declares 22 literal histogram bucket boundaries in its registration, from 0.001 to 2560.0.	Structural identity	10 hr ago

Related Use Cases (2)

Availability

vllm:time_to_first_token_seconds is registered as a Prometheus histogram in vLLM v0.23.0.

vllm.surface.prometheus_metricscomplete_inventoryPrometheusStatLogger metrics publisher

vLLM v0.23.0 v1 metrics loggers.py · vllm/v1/metrics/loggers.py:754-785