The bs>1 path regressed from the beginning of a run, so log throughput alone is not enough to identify whether scheduler preparation, batch splits, index/top-k, sync compose, HiCache load planning, or valid-row selection is dominating. Add a separate env-gated timing channel with rate and slow-threshold controls so production-like runs can identify the hot operation without enabling verbose structural debug logs.\n\nInstrumentation is intentionally observational: it does not change batch planning, cache residency, transfer semantics, or fast-path eligibility. The timing logs are limited and can be filtered by SGLANG_CP_SHARED_KV_BS_GT1_TIMING_SLOW_MS.\n\nConstraint: Need runtime evidence without starting traffic from the agent side.\nConstraint: Existing bs=1 batch-plan behavior remains expected and unchanged.\nRejected: Reuse SGLANG_CP_SHARED_KV_BS_GT1_DEBUG | existing debug logs are structural and already too noisy for timing diagnosis.\nRejected: Add unconditional timing logs | would perturb the hot path and flood long ETE runs.\nConfidence: high\nScope-risk: narrow\nDirective: Keep this timing channel observational; do not use it to gate behavior or silently change batch policy.\nTested: g0034 docker py_compile for changed Python files.\nTested: g0034 docker PYTHONPATH=python python -m pytest -q test/registered/unit/mem_cache/test_cp_shared_kv_runtime.py test/registered/unit/mem_cache/test_cp_hicache_load_back_owner_lanes.py test/registered/unit/mem_cache/test_cp_hicache_metadata.py — 241 passed, 5 warnings, 2 subtests passed.\nNot-tested: Live ETE timing log interpretation under user-driven traffic.\nNot-tested: Nsight correlation with timing events.
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