feat(monitoring): LLM observability dashboard + fix dead CAG rule

New Grafana dashboard (llm-observability) with 27 panels across 5 rows:
TTFT, inter-token latency, batching/scheduling, KV cache, throughput.

Both metric sources are shown side by side because they answer different
questions and neither is complete alone:

  vLLM 0.11.0 (reasoning) — engine truth: kv_cache_usage_perc,
    num_requests_running/waiting, num_preemptions_total, prefill vs
    decode time, prefix cache, per-request histogram quantiles.
  TEI 1.8.2 (embeddings, reranker) — te_batch_next_size, te_queue_size,
    te_embed_duration, te_embed_queue_duration.
  api-gateway — the ONLY per-request latency source covering Ollama
    models (ornith:35b, qwen2.5:3b-instruct), which expose no metrics.
    It is derived from the SSE byte stream, so it is streaming-only and
    counts SSE chunks rather than true tokens. vLLM's own histograms are
    authoritative for reasoning.

All 44 panel queries were executed against live Prometheus before commit —
all return success. vLLM/TEI panels have live series; gateway panels show
no data until the netpol fix in homelab-frontend PR #62 merges.

Also fixes a dead alert. alerts/cag-kv-cache-rules.yaml derived
vllm:prefix_cache_hit_rate from vllm:cache_query_hit_total and
vllm:cache_query_miss_total. Those metric names do not exist in vLLM
0.11.0 — the real series are vllm:prefix_cache_hits_total and
vllm:prefix_cache_queries_total. The recording rule produced no data, so
VLLMPrefixCacheHitRateLow could never fire.

Not included: real GPU hardware metrics (SM utilisation, framebuffer,
power, temperature). Only nvidia-device-plugin is deployed, which exposes
none of them; DCGM exporter is required. vllm:kv_cache_usage_perc and
preemption rate are the only GPU-pressure proxies available today.

This commit is contained in:

rock

2026-09-29 22:11:28 +08:00

parent 6ae36981bb

commit 1f3439c9e0

4 changed files with 261 additions and 4 deletions

									
										k8s/infra/monitoring/kustomization.yaml
									
		+1
		
												View File
												
				@@ -24,3 +24,4 @@ resources:

				  - servicemonitors/api-gateway.yaml

				  - dashboards/cluster-infrastructure.yaml

				  - dashboards/api-gateway.yaml

				  - dashboards/llm-observability.yaml