Files
project_6/ENGINE_CODEPATH_TIMELINE.md
Claude ee09550263 arch(CoreX): CCCL env_dispatch — try native fused kernels, fallback PyTorch
Three CoreX accelerators from base image (Sub168 had all three):
  1. corex_gdn — GatedDeltaNet fused prefill/decode
  2. corex_moe — MoE fused prefill/decode (expert-grouped-wmma)
  3. corex_fa2 — Flash Attention 2 (handled by xformers patches)

qwen3_5.py now 1477 lines (was 1369):
  - GatedDeltaNet.forward() → try CoreXGDN.forward() → except → PyTorch
  - Qwen3_5MoeSparseBlock.forward() → try corex_moe.moe_forward() → except → PyTorch
  - Module-level probe: import corex_gdn/corex_moe with graceful fallback

patch_ops.sh: always deploy our qwen3_5.py (it handles both scenarios)

If corex modules exist in base image → 10x speedup (Sub168 evidence)
If corex modules missing → same behavior as before (pure PyTorch)

Also added ENGINE_CODEPATH_TIMELINE.md — the full runtime diff
between Sub168 (score 60194) and our Sub508 (score 0).
2026-08-08 11:15:04 +00:00

151 lines
6.9 KiB
Markdown

# Engine Code Path Timeline: Sub168 vs Our Sub508/509
**Purpose**: Anyone reading this repo can understand the exact runtime difference in 2 minutes instead of re-deriving from raw logs.
## 1. Boot Sequence Comparison
```
TIME SUB168 (07-23, score=60194) OUR SUB508 (08-07, score=0)
──────────────────────────────────────────────────────────────────────────────────
+0s api_server.py:530 → vLLM 0.6.3 api_server.py:530 → vLLM 0.6.3
max_model_len=256000 max_model_len=256000 (same)
max_num_seqs=2, gpu_mem=0.95 max_num_seqs=2, gpu_mem=0.95 (same)
chunked_prefill=True chunked_prefill=True (same)
+10s model_runner.py:1074 load start model_runner.py:1119 load start
↑ DIFFERENT line number ↑ DIFFERENT line number
↑ (base image native model_runner) ↑ (our patched model_runner)
+18s weights = 17.3529 GB weights = 16.2303 GB
↑ 1.1GB MORE (corex state buffers) ↑ 1.1GB LESS (no corex buffers)
+180s corex_gdn.py:56 → load libcorex_gdn.so qwen3_5.py:445 → NaN in prefill layer 0
corex_gdn.py:228 → GDN prefill OK ↑ PyTorch GDN produces NaN (99.98%)
corex_moe.py:339 → MoE prefill OK qwen3_5.py:913 → FusedMoE FAILED
corex_fa2.py:333 → FA2 prefill OK ↑ ixformer.functions missing topk_softmax
↑ ALL THREE CoreX accelerators loaded ↑ ZERO accelerators, all fallback
+182s GPU blocks: 19259 GPU blocks: ~19000 (similar)
Ready to serve Ready to serve (but 10x slower)
```
## 2. Call Chain During Inference
### Sub168 (with CoreX) — d01_basic_nostream: 8.49s
```
serving_chat.py → create_chat_completion()
→ engine.generate()
→ model_runner.py:1074 execute_model()
→ qwen3_5.py:1421 Qwen3_5ForCausalLM.forward()
→ qwen3_5.py:1165 Qwen3_5Model.forward() (decoder layers loop)
→ qwen3_5.py:1086 Qwen3_5DecoderLayer.forward()
├─ GatedDeltaNet layers (4 of 36):
│ ├─ PREFILL: corex_gdn.py:228 → libcorex_gdn.so (fused CUDA kernel)
│ └─ DECODE: corex_gdn.py:138 → libcorex_gdn.so (fused CUDA kernel)
├─ MoE layers (all 36):
│ ├─ PREFILL: corex_moe.py:339 → libcorex_moe.so (expert-grouped-wmma)
│ └─ DECODE: corex_moe.py:249 → libcorex_moe.so (fused MoE decode)
└─ Attention (32 of 36 layers):
├─ PREFILL: corex_fa2.py:333 → libcorex_fa2.so (packed FA2)
└─ DECODE: corex_fa2.py:225 → libcorex_fa2.so (paged decode)
```
### Our Sub508 (no CoreX) — d01_basic_nostream: 95.87s (11.3x slower)
```
serving_chat.py → create_chat_completion()
→ engine.generate()
→ model_runner.py:1119 execute_model()
→ qwen3_5.py:1369 Qwen3_5ForCausalLM.forward() (52 lines shorter!)
→ qwen3_5.py:???? Qwen3_5Model.forward()
→ qwen3_5.py:???? Qwen3_5DecoderLayer.forward()
├─ GatedDeltaNet layers (4 of 36):
│ ├─ PREFILL: pure PyTorch conv1d → matmul → softmax (NaN!)
│ └─ DECODE: pure PyTorch _torch_causal_conv1d_update
├─ MoE layers (all 36):
│ ├─ PREFILL: PyTorch loop over unique_eids (SLOW)
│ └─ DECODE: PyTorch batched GEMM fallback
└─ Attention (32 of 36 layers):
├─ PREFILL: xformers _run_sdpa_fallback (patched, matmul+softmax)
└─ DECODE: xformers _run_sdpa_fallback
```
## 3. The Crash Chain (Sub508/509 → Score 0)
```
FUNCTIONAL TEST SEQUENCE:
d01_basic_nostream ✓ PASS (95.87s — slow but works)
d02_stream_usage ✓ PASS (1.84s)
d03_tool_call ✗ FAIL (49.04s — model thinks instead of emitting tool XML)
d04_reasoning ✓ PASS (128.74s)
... more tests pass ...
t2_n_2 ✗ FAIL → HTTP 500 → ENGINE PROCESS DIES
t3_max_tokens_none ✗ FAIL → HTTP 500 (engine dead, Connection Refused)
t3_max_tokens_1 ✗ FAIL → HTTP 500
t3_max_tokens_64 ✗ FAIL → HTTP 500
... 25 more tests ...
t16c_empty_messages ✗ FAIL → HTTP 500
───────────────────────────────────────
functional score: 21/51 = 0.412 (passed before crash)
case_truncation → Connection Refused → score=0.0
replay_tencent → 881/881 Connection Refused → score=0.0
opencompass → Connection Refused → score=0.0
───────────────────────────────────────
TOTAL: 0.0 (engine was dead for 90% of evaluation)
```
## 4. CoreX Dispatch Gap — The 52-Line Difference
Sub168's qwen3_5.py has ~1421 lines. Ours has 1369.
The missing ~52 lines are CoreX dispatch wrappers:
```python
# WHAT SUB168 HAS (reconstructed from log evidence):
# In GatedDeltaNet.__init__:
try:
from vllm.model_executor.models.corex_gdn import CoreXGDN
self._corex_gdn = CoreXGDN(...) # loads libcorex_gdn.so
except ImportError:
self._corex_gdn = None
# In GatedDeltaNet.forward() prefill path:
if self._corex_gdn is not None:
result = self._corex_gdn.prefill(...) # → corex_gdn.py:228
else:
result = self._pytorch_prefill(...) # our current pure PyTorch
# In Qwen3_5MoE.forward():
try:
from vllm.model_executor.models.corex_moe import corex_moe_forward
result = corex_moe_forward(...) # → corex_moe.py:339
except:
result = self._pytorch_moe_forward(...) # our current loop
```
## 5. Environment Variables (already set in YAML)
```yaml
VLLM_COREX_GDN_LIBRARY: /usr/local/corex/lib64/libcorex_gdn.so
VLLM_COREX_MOE_LIBRARY: /usr/local/corex/lib64/libcorex_moe.so
VLLM_COREX_FA2_LIBRARY: /usr/local/corex/lib64/libcorex_fa2.so
```
These .so files exist in the base image. The Python wrappers
(`corex_gdn.py`, `corex_moe.py`, `corex_fa2.py`) also exist in
the base image at:
`/usr/local/corex/lib/python3/dist-packages/vllm/model_executor/models/`
**Our qwen3_5.py simply never imports them.**
## 6. What Needs To Happen
Add try/except CoreX dispatch in 3 places in qwen3_5.py:
1. `GatedDeltaNet.forward()` — prefill + decode paths
2. `Qwen3_5MoE.forward()` — prefill + decode MoE dispatch
3. Attention — already handled by xformers patches (corex_fa2 is separate)
CCCL pattern: `dispatch_with_env` — try native kernel first, fallback on error.
Our Python equivalent: `try: corex_forward() except: pytorch_forward()`