frank-archon Laws: add the measured interference census (decode-only step
15.5 ms vs 166 ms chunk steps; 4.7% of steps hold 34% of step time; median
decode 166 -> 13 t/s above 5k prefill tok/s, per-stream 6.7 t/s = one token
per shared step; TTFT p90 2.4 -> 18.0 s for arriving requests), the lag test
that kills the residency theory, the busy_cap arithmetic, and the correction
that --prefill-interleave is the decoder dial and auto is not.
Facts that change how an operator reads this box: /diagnostics exists and
reports link-below-max at 100% busy; latency metrics live under vllm:, cadence
under radiance:; preemption is vllm:num_preemptions_total (264 this boot, all
bursts) while the radiance gauge is instant depth; both root ports are x8 Gen5
max by board (31.5 GB/s ceiling, not 64); DDR is back at 4800 MT/s while the
4600 corruption fix is recorded -- verify before blaming garbage tokens.
§9 (LLM Performance Diagnosis): method corrected to the phase-ratio counters,
dead 1.0.13 numbers destroyed, four PromQL traps added (metric prefix, 1 s EMA
gauges vs 15 s scrape, counter resets across builds, 2-minute mean diluting the
chunk), instruments that cannot be reached from Prometheus, and the knob list
priced from the pinned 1.8.1 source instead of the stale guide.
Frank
9f7457e39e