Gahow Wang 4b50c5a08d Fix unified cost model: include decode load in queue + hard overload gate ...

Two bugs caused elastic to concentrate load on cached instances (10x token
imbalance vs 2.7x baseline):

1. _instance_cost queue only counted pending_prefill_tokens, missing
   ongoing_decode_tokens entirely — instances with 50 decoding requests
   appeared idle to the cost model.

2. Cache hits made overloaded instances look "cheap", creating a positive
   feedback loop: more sessions → more cache → lower cost → more routing.
   Added a hard gate (ongoing_tokens > avg * overload_factor) that breaks
   affinity before the cost model runs, matching linear policy behavior.

Result: token imbalance 10.3x → 2.6x, TTFT p90 -37% vs baseline.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2026-05-24 16:25:02 +08:00

analysis

Add comprehensive research findings document

2026-05-23 07:16:31 +08:00

experiments

Add elastic PS evaluation plan for production-realistic trace

2026-05-23 15:56:05 +08:00

patches

Add vLLM patches directory for version-controlled patch management

2026-05-22 00:26:14 +08:00

replayer

Fix multi-turn replay fidelity: track realized output tokens across all components

2026-05-24 14:47:51 +08:00

scripts

Fix unified cost model: include decode load in queue + hard overload gate

2026-05-24 16:25:02 +08:00

tests

proxy: Settings dataclass + cache-ratio gate + P-pick offload penalty (B4, M2, M3, D5)

2026-05-23 21:11:17 +08:00

third_party/vllm

Fix multi-turn replay fidelity: track realized output tokens across all components

2026-05-24 14:47:51 +08:00

.gitignore

Phase 1 milestone: system-level analysis + reproducible report

2026-05-22 16:17:41 +08:00

FIXES.md

Add FIXES.md with prioritized repo cleanup checklist

2026-05-23 20:35:56 +08:00

pyproject.toml

tests: add minimal coverage for percentile + proxy routing (S1)

2026-05-23 21:07:14 +08:00

REPORT.md

Fix A+C: real cache sync + cached-prefill-on-C architecture

2026-05-24 11:22:38 +08:00

TODO.md

LMetric routing policy (OSDI'26) + A/B results vs linear baseline

2026-05-22 16:57:32 +08:00

uv.lock

Fix NONE_HASH import: use module ref instead of from-import (value binding bug)

2026-05-24 01:32:19 +08:00

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