Add trace length bucket tuning support

configs/examples/dash0_qwen27b_tight_slo_run2.json

@@ -0,0 +1,147 @@
+{
+  "study_id": "dash0-qwen27b-tight-slo-10min-run2",
+  "hardware": {
+    "gpu_count": 4,
+    "gpu_model": "H20",
+    "host_candidates": [
+      "dash0"
+    ]
+  },
+  "model": {
+    "model_id": "qwen3.5-27b-256k-0223-internal",
+    "served_model_name": "qwen35-27b-aituner"
+  },
+  "engine": {
+    "engine_name": "vllm",
+    "engine_version": "latest-release-on-dash0",
+    "exec_path": "/usr/local/bin/vllm",
+    "cwd": "/home/admin/cpfs/wjh/aituner/aituner",
+    "host": "127.0.0.1",
+    "port": 18082,
+    "healthcheck_path": "/v1/models",
+    "ready_timeout_s": 900,
+    "request_timeout_s": 900,
+    "launch_args": [
+      "serve",
+      "/home/admin/resource/model/464482ce/qwen3.5-27b/256k-0223-internal"
+    ],
+    "base_envs": {
+      "CUDA_VISIBLE_DEVICES": "4,5,6,7",
+      "VLLM_DISABLE_COMPILE_CACHE": "1",
+      "DS_LLM_IGNORE_WARMUP": "1",
+      "DS_LLM_IGNORE_CHECK_WARMUP": "1",
+      "VLLM_ENABLE_MODEL_RUNNER_WARMUP": "1",
+      "VLLM_GDN_USE_FUSED_QKVZBA_KERNEL": "0",
+      "PARAM_TOTAL_MAX": "262144",
+      "PARAM_IN_LENGTH_MAX": "262144",
+      "PARAM_MAX_LENGTH_MAX": "131072",
+      "DS_LLM_MAX_THINK_TOKENS": "81920",
+      "DS_LLM_GRACEFUL_SHUTDOWN_WAIT_SECONDS": "600",
+      "VLLM_FP8_USE_BLADNN": "1",
+      "VLLM_MOE_USE_BLADNN": "1",
+      "VLLM_GDN_USE_BLADNN": "0",
+      "VLLM_USE_V1": "1",
+      "VLLM_IS_HYBRID_MODEL": "1",
+      "VLLM_ENABLE_TORCH_COMPILE": "1",
+      "VLLM_ATTENTION_BACKEND": "FLASH_ATTN",
+      "VLLM_QUANTIZE_ROUTED_EXPERTS_ONLY": "1",
+      "VLLM_USE_FLASHINFER_SAMPLER": "0",
+      "VLLM_RESPONSE_TIMEOUT": "300",
+      "VLLM_LOG_REQ_KV_LENS": "1",
+      "DS_LLM_GRACEFUL_SHUTDOWN_KEEP_SECONDS": "600"
+    },
+    "base_flags": {
+      "host": "127.0.0.1",
+      "port": 18082,
+      "served-model-name": "qwen35-27b-aituner",
+      "trust-remote-code": true,
+      "dtype": "bfloat16",
+      "gpu-memory-utilization": 0.9,
+      "enable-prefix-caching": true,
+      "mamba-cache-mode": "light",
+      "distributed-executor-backend": "mp",
+      "block-size": 64,
+      "enable-chunked-prefill": true,
+      "max-num-batched-tokens": 8192,
+      "disable-cascade-attn": true,
+      "max-model-len": 262144,
+      "speculative-config": "{\"method\":\"qwen3_next_vl_mtp\",\"num_speculative_tokens\":3}",
+      "mm-processor-cache-gb": 0,
+      "limit-mm-per-prompt": "{\"image\":256,\"video\":64}",
+      "compilation-config": "{\"cudagraph_mode\":\"FULL_AND_PIECEWISE\",\"use_inductor\":false,\"pass_config\":{\"fuse_norm_quant\":false,\"fuse_act_quant\":false,\"fuse_attn_quant\":false}}",
+      "mamba-cache-dtype": "float32",
+      "skip-mm-profiling": true,
+      "quantization": "fp8",
+      "tensor-parallel-size": 4,
+      "max-num-seqs": 16,
+      "disable-log-requests": true
+    },
+    "tunable_envs": [
+      "VLLM_ATTENTION_BACKEND",
+      "VLLM_ENABLE_TORCH_COMPILE",
+      "VLLM_USE_FLASHINFER_SAMPLER",
+      "VLLM_ENABLE_MODEL_RUNNER_WARMUP"
+    ],
+    "tunable_flags": [
+      "tensor-parallel-size",
+      "gpu-memory-utilization",
+      "block-size",
+      "max-num-batched-tokens",
+      "max-num-seqs",
+      "enable-prefix-caching",
+      "enable-chunked-prefill",
+      "disable-cascade-attn"
+    ],
+    "python_executable": "python3"
+  },
+  "trace": {
+    "windows_path": "/home/admin/cpfs/wjh/aituner/aituner/trace_windows/windows.json",
+    "window_id": "chat_w20260311_1000",
+    "u_field": "sampling_u",
+    "timestamp_field": "timestamp",
+    "max_concurrency": 32,
+    "replay_time_scale": 1.0,
+    "early_stop_max_lag_s": 120.0,
+    "early_stop_max_elapsed_s": 900.0
+  },
+  "slo": {
+    "target_pass_rate": 0.95,
+    "ttft_rule": {
+      "kind": "step_ms",
+      "buckets": [
+        {
+          "max_input_tokens": 4096,
+          "threshold_ms": 2000
+        },
+        {
+          "max_input_tokens": 32768,
+          "threshold_ms": 4000
+        },
+        {
+          "threshold_ms": 6000
+        }
+      ]
+    },
+    "tpot_rule": {
+      "kind": "fixed_ms",
+      "threshold_ms": 50
+    }
+  },
+  "search": {
+    "low": 0.0,
+    "high": 0.0625,
+    "tolerance": 0.001,
+    "max_probes": 6,
+    "sample_seed": 20260325
+  },
+  "llm": {
+    "system_prompt": "Propose a single engine config patch that increases the maximum feasible sampling_u under the SLO target. Favor launch-safe changes grounded in the incumbent result and only propose knobs that plausibly improve throughput above the incumbent request rate.",
+    "max_history_trials": 8,
+    "endpoint": {
+      "base_url": "http://tianx.ipads-lab.se.sjtu.edu.cn:8317/v1",
+      "model": "gpt-5.4",
+      "api_key_env": "OPENAI_API_KEY",
+      "timeout_s": 180
+    }
+  }
+}