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Use time-compressed community vllm ablation

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Gahow Wang
2026-05-02 10:03:59 +08:00
parent d3d4c234f6
commit ccbf24ac47
3 changed files with 8 additions and 7 deletions
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docs/qwen30b-community-vllm020/harness-early-stop-ablation-20260502.md
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@@ -40,6 +40,7 @@ The experiment reuses the 0-8k chat window that has already been used for qwen27
| input filter | 0 to 8192 tokens |
| completion tokens | fixed 128 via `trace.completion_tokens_override` |
| max requests per probe | 512 |
| replay time scale | 0.1 |
| target pass rate | 0.95 |
| TTFT SLO | 2s up to 4k, 4s up to 32k, 6s above |
| TPOT SLO | 50ms |
@@ -48,7 +49,7 @@ The experiment reuses the 0-8k chat window that has already been used for qwen27
The `max_requests_per_probe=512` cap keeps the fresh community-vLLM ablation practical while preserving a real trace-shaped replay, SLO scoring, and binary-search threshold probe. A trace-only count check gives 31 to 65 selected requests across the six binary-search thresholds, avoiding the invalid low-cap case where early thresholds can select zero requests.
The first full-output attempt showed why a bounded replay is needed for a 12-iteration ablation: at the first threshold (`0.0625`), 31 selected requests contained 14,849 output tokens with `out_max=2981`. That makes one probe too slow to finish a full no-harness/harness pair. The active ablation therefore fixes output length at 128 tokens and limits each trial to four binary-search probes. This changes the decode mix, so the result should be interpreted as a community-vLLM harness convergence test under a bounded chat replay, not as a full-output production benchmark.
The first full-output attempt showed why a bounded replay is needed for a 12-iteration ablation: at the first threshold (`0.0625`), 31 selected requests contained 14,849 output tokens with `out_max=2981`. That makes one probe too slow to finish a full no-harness/harness pair. The first out128 attempt with `replay_time_scale=1.0` was still bounded by real window time, so each probe waited close to the original window duration. The active ablation therefore fixes output length at 128 tokens, uses `replay_time_scale=0.1`, and limits each trial to four binary-search probes. `load_trace_requests` scales both request arrivals and the window duration, so reported request rates are the actual compressed replay request rates. This changes the load/decode mix, so the result should be interpreted as a community-vLLM harness convergence test under a bounded, time-compressed chat replay, not as a full-output production benchmark.
## Harness Update Under Test
@@ -91,8 +92,8 @@ Pending dash0 runs:
| Variant | tmux session | Log | Study root |
| --- | --- | --- | --- |
| no-harness | `qwen30b_vllm020_noharness_out128_probe512_20260502` | `logs/qwen30b_vllm020_noharness_out128_probe512_20260502.log` | `.aituner-community-vllm020/dash0-qwen30b-a3b-community-vllm020-chat-0-8k-out128-probe512-noharness` |
| harness | `qwen30b_vllm020_harness_out128_probe512_20260502` | `logs/qwen30b_vllm020_harness_out128_probe512_20260502.log` | `.aituner-community-vllm020/dash0-qwen30b-a3b-community-vllm020-chat-0-8k-out128-probe512-harness` |
| no-harness | `qwen30b_vllm020_noharness_out128_scale01_20260502` | `logs/qwen30b_vllm020_noharness_out128_scale01_20260502.log` | `.aituner-community-vllm020/dash0-qwen30b-a3b-community-vllm020-chat-0-8k-out128-scale01-noharness` |
| harness | `qwen30b_vllm020_harness_out128_scale01_20260502` | `logs/qwen30b_vllm020_harness_out128_scale01_20260502.log` | `.aituner-community-vllm020/dash0-qwen30b-a3b-community-vllm020-chat-0-8k-out128-scale01-harness` |
The harness run should be judged by best-so-far `request_rate_per_gpu` per tuning iteration, plus whether it stops only after validation evidence. The no-harness run should use the same trial budget so the ablation exposes whether the early-stop harness saves iterations without hiding a later better point.