vllm/docs/usage/metrics.md

Production Metrics

vLLM exposes a number of metrics that can be used to monitor the health of the system. These metrics are exposed via the /metrics endpoint on the vLLM OpenAI compatible API server.

You can start the server using Python, or using [Docker][deployment-docker]:

vllm serve unsloth/Llama-3.2-1B-Instruct

Then query the endpoint to get the latest metrics from the server:

$ curl http://0.0.0.0:8000/metrics

# HELP vllm:iteration_tokens_total Histogram of number of tokens per engine_step.
# TYPE vllm:iteration_tokens_total histogram
vllm:iteration_tokens_total_sum{model_name="unsloth/Llama-3.2-1B-Instruct"} 0.0
vllm:iteration_tokens_total_bucket{le="1.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="8.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="16.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="32.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="64.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="128.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="256.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
vllm:iteration_tokens_total_bucket{le="512.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
...

The following metrics are exposed:

--8<-- "vllm/engine/metrics.py:metrics-definitions"

The following metrics are deprecated and due to be removed in a future version:

• vllm:num_requests_swapped, vllm:cpu_cache_usage_perc, and vllm:cpu_prefix_cache_hit_rate because KV cache offloading is not used in V1.
• vllm:gpu_prefix_cache_hit_rate is replaced by queries+hits counters in V1.
• vllm:time_in_queue_requests because it duplicates vllm:request_queue_time_seconds.
• vllm:model_forward_time_milliseconds and vllm:model_execute_time_milliseconds because prefill/decode/inference time metrics should be used instead.

Note: when metrics are deprecated in version X.Y, they are hidden in version X.Y+1 but can be re-enabled using the --show-hidden-metrics-for-version=X.Y escape hatch, and are then removed in version X.Y+2.