c9d350b372
Document the iterative debugging from v1 (broken KVC) through v4
(routing fixed + session cap raised), with code-level analysis of
the two main bugs encountered:
1. v2 root cause (mis-diagnosed previously as `allow_local_prefill`):
`--policy default` for KVC mechanism caused replay's round-robin
policy and the PD router's round-robin to diverge, sending requests
with `session_params` to a D worker that did not have the session
open. Resulted in 56-61% truncation with finish_reason
"session id X does not exist".
Fix: use `--policy kv-aware` (sweep_tp1_v3_kvaware.sh) so replay
emits `x-smg-target-worker` and PD router uses consistent_hashing.
2. v3 new bottleneck: `pd-router-fallback-large-append-session-cap`
dominated 52-65% of requests. Root cause was hardcoded
`min(4, ...)` in `_decode_session_soft_cap`. With 7 D workers x 4
sessions = 28 slots for 52 trace sessions, ~24 sessions starved
permanently (bimodal direct-to-D rate of 0% or 99%).
Fix: raise the cap to 16 (replay.py).
Also includes the v3 finding that direct-to-d-session path P50=0.495s
and TTFT P50=0.043s already beats the 8-way DP baseline (0.65s/0.093s)
- the KVC core mechanism works when fallback paths are avoided.
Files:
- docs/KVC_DEBUG_JOURNEY_V1_TO_V4.md: full journey + code location index
- docs/SWEBENCH_EXPERIMENT_{PROGRESS,RESULTS}.md: prior session notes
- scripts/sweep_tp1_v{2,3,4}*.sh: experiment driver scripts
- src/agentic_pd_hybrid/replay.py: cap 4 -> 16, audit fields
- src/agentic_pd_hybrid/pd_router.py: strip session_params from prefill
- src/agentic_pd_hybrid/metrics.py: truncated_request_count
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
61 lines
1.6 KiB
Bash
Executable File
61 lines
1.6 KiB
Bash
Executable File
#!/bin/bash
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# KVC admission control parameter sweep on Qwen3-30B
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# 5 experiments, ~35 min each, ~3 hours total
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set -euo pipefail
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cd "$(dirname "$0")/.."
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MODEL=/mnt/kzlin/workflow/pd-hybrid/simm-swe-bench/models/Qwen3-30B-A3B-Instruct-2507
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TRACE=outputs/qwen35-swebench-50sess.jsonl
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OUTPUT=outputs/qwen3-30b-exps
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VENV_PYTHON=.venv/bin/python
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run_kvc() {
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local label=$1
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local inflight=$2
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local min_turn=$3
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echo "=== [$label] inflight=$inflight min_turn=$min_turn === $(date)"
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PYTHONPATH=src:third_party/sglang/python \
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$VENV_PYTHON -m agentic_pd_hybrid.cli benchmark-live \
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--trace $TRACE \
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--output-root $OUTPUT \
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--mechanism kvcache-centric \
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--policy default \
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--model-path $MODEL \
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--prefill-workers 1 --decode-workers 1 \
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--prefill-tp-size 4 --decode-tp-size 4 \
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--prefill-gpu-ids 0,1,2,3 --decode-gpu-ids 4,5,6,7 \
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--transfer-backend mooncake \
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--gpu-budget 8 \
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--time-scale 10 \
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--session-sample-rate 1.0 \
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--target-duration-s 100000 \
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--concurrency-limit 32 \
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--timeout-s 900 \
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--request-timeout-s 300 \
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--kvcache-admission-mode worker \
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--kvcache-seed-min-turn-id $min_turn \
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--kvcache-seed-max-inflight-decode $inflight \
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--kvcache-prefill-backup-policy release-after-transfer \
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--kvcache-prefill-priority-eviction
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echo "=== [$label] DONE === $(date)"
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echo ""
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}
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# C1: inflight=8, min-turn=2
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run_kvc "C1" 8 2
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# C2: inflight=16, min-turn=2
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run_kvc "C2" 16 2
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# C3: inflight=-1 (disabled), min-turn=2
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run_kvc "C3" -1 2
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# C4: inflight=8, min-turn=1
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run_kvc "C4" 8 1
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# C5: inflight=-1 (disabled), min-turn=1
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run_kvc "C5" -1 1
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echo "=== ALL SWEEP EXPERIMENTS DONE === $(date)"
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