[Bugfix] grafana.json: rename vllm:gpu_cache_usage_perc to vllm:kv_cache_usage_perc

[ctrueblood-epri]

Purpose

Update grafana.json to rename the deprecated metric "vllm:gpu_cache_usage_perc" to "vllm:kv_cache_usage_perc". This change is required for Cache Utilization to display values on a Grafana dashboard as of vLLM 0.11.0.

For reference, the GPU cache usage metric was renamed and deprecated here: vllm/v1/metrics/loggers.py#L415-L438

Test Plan

1. Install and run vLLM version 0.11.0
2. Configure Prometheus and Grafana as instructed here: https://docs.vllm.ai/en/latest/examples/online_serving/prometheus_grafana.html
3. In Grafana edit JSON model by renaming "vllm:gpu_cache_usage_perc" to "vllm:kv_cache_usage_perc" and "GPU Cache Usage" to "KV Cache Usage"

Test Result

Success. Cache Utilization now displays values on the Grafana dashboard.

[github-actions]

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[mergify]

Documentation preview: https://vllm--27341.org.readthedocs.build/en/27341/

[gemini-code-assist]

Code Review

The pull request renames the deprecated metric "vllm:gpu_cache_usage_perc" to "vllm:kv_cache_usage_perc" in grafana.json. This change ensures that Cache Utilization displays values correctly on a Grafana dashboard for vLLM version 0.11.0 and later. I have provided a review comment to address a critical issue.

[markmc]

Thanks, #27133 has the same fix and is ready to merge

[markmc]

Fixed by #27133, thanks again