Previous comments described llm_ttft_seconds / llm_itl_seconds /
llm_tokens_total as "streaming-only". That was wrong, and optimistic.
They are dead code. internal/proxy/llm_metrics.go defines
LLMMetricsCapture, which is the only thing that calls RecordTTFT /
RecordITL / RecordTokens — but NewLLMMetricsCapture() has zero call sites
anywhere in the repo, verified by grep. The exporter skips keys with no
samples, so those three series render as HELP-only stubs and can never be
graphed, streaming or not.
No behaviour change here; only the comments and the dashboard generator's
header are corrected so the next person does not build on a false
assumption. The gateway latency panels are left in place so the gap stays
visible — they populate unchanged once the capture wrapper is wired into
the streaming proxy path.
Series that DO work from the gateway, confirmed live with 3 series (one
per replica): queue_full_requests_total, warmup_requests_delayed_total,
vllm_prefix_cache_hit_tokens_total.
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.
rock