unsloth/scripts/benchmarks/results/stats/cb_sync_smoke.json
Daniel Han 5f3e1c98df Phase 2 vibe (10-step): vllm vs unsloth_fi_false vs cb_paged + Phase 3 fixes
Phase 2 results (`scripts/benchmarks/results/grpo_equivalence.md`):
- vLLM: 74.4s train, 4.14s median step, 158 GB peak (100%)
- unsloth_fi_false: 355s train, 23.95s median, 10.7 GB peak (17%)
- cb_paged (via sdpa_paged load): 466s train, 36s median, 55.6 GB peak (11.5%)

Coherence gate passes on all three backends: losses finite, rewards in the
expected early-GRPO range, KL trajectories qualitatively matched between
vLLM and unsloth_fi_false in [0, 0.015]. Memory story is striking:
unsloth_fi_false uses 15x less memory than vLLM.

qwen3_grpo_unified.py fixes:
- Auto-adjust per_device_train_batch_size -> num_generations for vanilla-HF
  backends (Unsloth's loader does this automatically; TRL on the HF path
  doesn't and crashes on the divisibility check).
- cb_paged now loads with sdpa_paged (not paged_attention). The FA4
  paged_attention kernel requires cu_seq_lens_q on every forward, but the
  GRPO training forward feeds a dense batch without them. sdpa_paged
  gracefully falls back to plain SDPA in that case and still exercises the
  paged path during the CB rollout.

cb_sync_driver.py fixes:
- FIFOScheduler no longer accepts manual_eviction in its signature; dropped.
- drive_until_empty used to check has_pending_requests() before calling
  prepare_next_batch(), which returned False at startup because nothing had
  yet been pulled from the input_queue. Now the loop drains the input queue
  first and exits only when both queues + scheduler are empty.

Smoke test on GPU 1 (8 prompts, 64 tokens): eager path produces 512 correct
tokens; CUDA-graph path hangs during first-step capture (PagedAttentionCache
probably allocates on first use). Tracked for the next commit.
2026-04-20 14:23:51 +00:00

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{
"backend": "cb_sync_driver",
"use_cuda_graph": false,
"attn_impl": "paged_attention",
"n_prompts": 8,
"n_decoded_tokens": 512,
"wall_times_s": [
100.8571443540277,
100.87157070200192
],
"median_wall_s": 100.87157070200192,
"decode_tps": 5.075761152887835,
"max_new_tokens": 64,
"peak_memory_gb": 45.91296434402466
}