Training Qwen3.6-27B on B200

Author

ATTUNE (cite)

GPUs

8 x B200 180 GB (AWS p6-b200.48xlarge, 8 per node)

Layout

TP 1, PP 8 (7 layers on the first stage, 9 on each of the six middle stages, 3 on the last), CP 1, DP 1; one 8,192-token row per microbatch; full recompute of the first 2 layers of each stage (block); precision-aware distributed optimizer; no offload; dense model, no experts

Tokens/s per GPU

4,330.87

$ / 1M tokens

$0.91

MFU

29.6% (N = 25,623,920,640 active parameters per token)

Step-time CV

1.08%

Convergence check

correlation 0.9999729, final loss difference 0.00077, 0 pointwise failures over 20 steps

Component test

precision-aware Adam on the GPU and CPU optimizer offload (fraction 1.0, overlapped copies), each against an FP64 reference: B200, 2026-10-14. Shape: one Qwen3.5-397B-A17B MoE layer: hidden 4096, 512 experts, top-10, expert FFN 1024, EP 8, ETP 1, 4,096 tokens per rank. worst tensor (update) relative L2 error 5.12e-7 on the GPU and 7.99e-7 offloaded against a bound of 1.0e-3 after one step, and 4.99e-5 and 7.73e-5 against 1.1e-3 after three steps at the recipe's hyperparameters (bound 2 x the default GPU optimizer's error + 1e-3); reconstructed FP32 masters bitwise identical to an arm with explicit FP32 masters, the TE remainder self-test passes and the negative controls fail run on B200 on this recipe's training image; the optimizer step is elementwise, so the result holds for every model on the image

Measured

2026-10-18

GPU-hours

3.13

Rows

qwen35-tulu3-fixed8192-v1 (rows_sha256 7a837641dcde9ebcac9d3ed5ed84ddd941fc9bfc173606cc701e9a3f51c307f1)

export CUDA_DEVICE_MAX_CONNECTIONS=1
export PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True
export TORCHINDUCTOR_COMPILE_THREADS=1
export NCCL_NVLS_ENABLE=$([ "$NVLINK_COUNT" -gt 0 ] && echo 1 || echo 0)

python3 -m <slime entry module> --async \
  --actor-num-nodes 1 \
  --actor-num-gpus-per-node 8 \
  ${MODEL_ARGS[@]} \
  --hf-checkpoint "$HF_CKPT" \
  --ref-load "$TORCH_DIST" \
  --rollout-function-path pretokenized_sft_rollout.generate_rollout \
  --prompt-data "$SFT_DATA" \
  --input-key messages \
  --metadata-key metadata \
  --num-rollout 20 \
  --rollout-batch-size 128 \
  --global-batch-size 128 \
  --loss-type sft_loss \
  --loss-mask-type qwen3_5 \
  --calculate-per-token-loss \
  --disable-compute-advantages-and-returns \
  --debug-train-only \
  --tensor-model-parallel-size 1 \
  --pipeline-model-parallel-size 8 \
  --decoder-first-pipeline-num-layers 7 \
  --decoder-last-pipeline-num-layers 3 \
  --context-parallel-size 1 \
  --expert-model-parallel-size 1 \
  --expert-tensor-parallel-size 1 \
  --sequence-parallel \
  --recompute-granularity full \
  --recompute-method block \
  --recompute-num-layers 2 \
  --use-dynamic-batch-size \
  --max-tokens-per-gpu 8192 \
  --optimizer adam --lr 1e-5 --lr-decay-style cosine --min-lr 1e-6 \
  --lr-warmup-fraction 0.1 --weight-decay 0.1 --adam-beta1 0.9 --adam-beta2 0.98 \
  --use-distributed-optimizer \
  --use-precision-aware-optimizer \
  --attention-dropout 0.0 --hidden-dropout 0.0 \
  --accumulate-allreduce-grads-in-fp32 --attention-softmax-in-fp32 \
  --attention-backend flash \
  --distributed-timeout-minutes 30 \
  --tensorboard-dir "$PROFILE_DIR"

# recipes/qwen3.6-27b/b200/attune-tp1-pp8-split7-rb2.yaml
# An OpenRecipes recipe; the fields are documented in schema/recipe.schema.yaml.
schema_version: 1
model: Qwen3.6-27B
gpu:
  type: B200
  memory_gb: 180
  count: 8
  per_node: 8
  instance: AWS p6-b200.48xlarge
author:
  name: ATTUNE
  url: https://arxiv.org/abs/2610.17528
status: verified
stack:
  framework: 'slime 0.3.0: THUDM/slime a897e1f plus 8 commits that do not change the training step'
  megatron_lm: commit 1dcf0daf (megatron-core 0.16.0rc0), with a backported upstream fix for the Qwen3.5 attention output
    gate at TP above the query-group count
  transformer_engine: 2.10.0
  pytorch: 2.11.0 (CUDA 12.9 build)
  cuda: '12.9'
  nccl: 2.28.9 (CUDA 12.9 build; printed by the measured run)
  deepep: 1.2.1
  python: 3.12.3
  fla: 0.4.1 (flash-linear-attention)
  triton: 3.6.0
  network: 8 GPUs per node, EFA, 3.2 Tb/s RDMA per node
  runtime_fixes: patches/fla_blackwell_guard.py, imported in every training process before FLA
  source: 'in-pod version check of the measured run''s training image (same digest) on 2026-10-18: installed TE,
    PyTorch, DeepEP, megatron-core, FLA and Triton, Megatron-LM git commit, Python; NCCL from the measured run''s log'
workload:
  row_tokens: 8192
  rows: SFT conversations
  global_batch: 128
  precision: bf16
  dataset:
    name: Tulu 3 SFT mixture
    source: allenai/tulu-3-sft-mixture
    revision: b14afda60f1bbebe55d5d2fa1e4df5042f97f8be
    license: ODC-By 1.0
    rows_sha256: 7a837641dcde9ebcac9d3ed5ed84ddd941fc9bfc173606cc701e9a3f51c307f1
    build:
      name: qwen35-tulu3-fixed8192-v1
      tokenizer: Qwen3.5 (the Qwen3.5-122B-A10B tokenizer; tokenizer.json sha256 5f9e4d4901a92b997e463c1f46055088b6cca5ca61a6522d1b9f64c4bb81cb42)
      loss_mask: qwen3_5
      rows: 6400
      row_tokens: 8192
      padding_tokens: 0
      seed: 42
      packing: source conversations in a seeded global permutation, concatenated with an EOS token between them and cut
        into consecutive 8,192-token rows; rows without supervised targets are skipped
      supervised_token_ratio: 0.676
      parquet_sha256: f215bdc6aba60d6d0dff4471eaef805765cb393e40b95762190535376491ab01
      parquet_bytes: 76127393
      builder: data/generate_fixed_sft.py (data/README.md)
layout:
  label: TP1 PP8
  summary: TP 1, PP 8 (7 layers on the first stage, 9 on each of the six middle stages, 3 on the last), CP 1, DP 1; one
    8,192-token row per microbatch; full recompute of the first 2 layers of each stage (block); precision-aware
    distributed optimizer; no offload; dense model, no experts
  highlights: 7/9/9/9/9/9/9/3 layer split, block recompute of 2 layers, no offload
  tp: 1
  pp: 8
  vpp: 1
  cp: 1
  ep: 1
  etp: 1
  dp: 1
  sequence_parallel: false
  layer_split:
    first: 7
    last: 3
  max_tokens_per_gpu: 8192
  rows_per_microbatch: 1
  recompute:
    granularity: full
    method: block
    num_layers: 2
  offload: null
  dispatcher: null
result:
  tokens_per_s_per_gpu: 4330.87
  usd_per_million_tokens: 0.91
  step_time_cv_percent: 1.08
  mfu: 0.2959
  mfu_note: null
  active_params:
    count: 25623920640
    source: https://huggingface.co/Qwen/Qwen3.6-27B
    revision: 6a9e13bd6fc8f0983b9b99948120bc37f49c13e9
  measured: 2026-10-18
  steps_per_run: 20
  window:
  - 5
  - 19
  window_tokens: 15728640
  runs: 1
  profiler: false
  gpu_hours: 3.13
  gpu_hours_note: GPUs x (scheduler admission to finish), including startup; the same run is the candidate arm of the
    convergence check
correctness:
  result: pass
  summary: passed; 1 component test passed on this image
  reference: 'The layout of slime''s `scripts/run-qwen3.5-27B.sh` on one 8-GPU node: TP 4 with sequence parallelism, PP
    2 (first stage 34 layers, last 30), CP 1 in place of its CP 4, full recompute and CPU optimizer offload, with this
    recipe''s optimizer settings.'
  configuration: pass
  component_tests:
  - test: precision-aware Adam on the GPU and CPU optimizer offload (fraction 1.0, overlapped copies), each against an
      FP64 reference
    shape: 'one Qwen3.5-397B-A17B MoE layer: hidden 4096, 512 experts, top-10, expert FFN 1024, EP 8, ETP 1, 4,096 tokens
      per rank'
    gpu: B200
    date: 2026-10-14
    result: pass
    detail: worst tensor (update) relative L2 error 5.12e-7 on the GPU and 7.99e-7 offloaded against a bound of 1.0e-3
      after one step, and 4.99e-5 and 7.73e-5 against 1.1e-3 after three steps at the recipe's hyperparameters (bound
      2 x the default GPU optimizer's error + 1e-3); reconstructed FP32 masters bitwise identical to an arm with explicit
      FP32 masters, the TE remainder self-test passes and the negative controls fail
    note: run on B200 on this recipe's training image; the optimizer step is elementwise, so the result holds for every
      model on the image
  convergence:
    steps: 20
    result: pass
    correlation: 0.9999729
    final_loss_difference: 7.7e-04
    pointwise_failures: 0
    note: 'candidate arm: the measured run; reference arm: a 20-step run of the reference recipe on the same image and
      rows; the parity probe off in both; both with patches/fla_blackwell_guard.py'
  rules: argument classes of ATTUNE's skill/scripts/correctness/rules/numerics_list.yaml (amazon-science/attune f2cb450),
    with CPU optimizer offload admitted by the B200 component test above; 20-step check by Megatron-Bridge
    validate_convergence with its pipeline thresholds
env:
  CUDA_DEVICE_MAX_CONNECTIONS: '1'
  PYTORCH_CUDA_ALLOC_CONF: expandable_segments:True
  TORCHINDUCTOR_COMPILE_THREADS: '1'
  NCCL_NVLS_ENABLE: $([ "$NVLINK_COUNT" -gt 0 ] && echo 1 || echo 0)
patches:
- patches/fla_blackwell_guard.py
run: |
  export CUDA_DEVICE_MAX_CONNECTIONS=1
  export PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True
  export TORCHINDUCTOR_COMPILE_THREADS=1
  export NCCL_NVLS_ENABLE=$([ "$NVLINK_COUNT" -gt 0 ] && echo 1 || echo 0)

  python3 -m <slime entry module> --async \
    --actor-num-nodes 1 \
    --actor-num-gpus-per-node 8 \
    ${MODEL_ARGS[@]} \
    --hf-checkpoint "$HF_CKPT" \
    --ref-load "$TORCH_DIST" \
    --rollout-function-path pretokenized_sft_rollout.generate_rollout \
    --prompt-data "$SFT_DATA" \
    --input-key messages \
    --metadata-key metadata \
    --num-rollout 20 \
    --rollout-batch-size 128 \
    --global-batch-size 128 \
    --loss-type sft_loss \
    --loss-mask-type qwen3_5 \
    --calculate-per-token-loss \
    --disable-compute-advantages-and-returns \
    --debug-train-only \
    --tensor-model-parallel-size 1 \
    --pipeline-model-parallel-size 8 \
    --decoder-first-pipeline-num-layers 7 \
    --decoder-last-pipeline-num-layers 3 \
    --context-parallel-size 1 \
    --expert-model-parallel-size 1 \
    --expert-tensor-parallel-size 1 \
    --sequence-parallel \
    --recompute-granularity full \
    --recompute-method block \
    --recompute-num-layers 2 \
    --use-dynamic-batch-size \
    --max-tokens-per-gpu 8192 \
    --optimizer adam --lr 1e-5 --lr-decay-style cosine --min-lr 1e-6 \
    --lr-warmup-fraction 0.1 --weight-decay 0.1 --adam-beta1 0.9 --adam-beta2 0.98 \
    --use-distributed-optimizer \
    --use-precision-aware-optimizer \
    --attention-dropout 0.0 --hidden-dropout 0.0 \
    --accumulate-allreduce-grads-in-fp32 --attention-softmax-in-fp32 \
    --attention-backend flash \
    --distributed-timeout-minutes 30 \
    --tensorboard-dir "$PROFILE_DIR"
notes: |
  - Starting point: slime's Qwen3.5-27B script, `scripts/run-qwen3.5-27B.sh` with `scripts/models/qwen3.5-27B.sh` at
    slime 0.3.0. slime ships it as a 4-node GRPO script and publishes no tokens/s figure for it. Ported to this
    workload on one 8-GPU node with its layout (TP 4 with sequence parallel, PP 2 with 34/30 layers, CP 1 in place of
    its CP 4, full recompute, Adam on the CPU), it measured 1,434.4 tokens/s/GPU on 8 B200; ATTUNE tuned it to 4,330.9
    (+202%).
  - Recompute is at the memory limit: the tuning run with block recompute of 1 layer ran out of memory on the second
    stage (164.1 GiB allocated of 178 GiB).
  - Step 0 of the measured run took 718 s, against about 30 s for each later step.
  - B200 runs of this model need `patches/fla_blackwell_guard.py`: with the image's Triton 3.6, FLA 0.4.1's autotuner
    picks gated-delta-net kernel configs that race on Blackwell and give a different, wrong result on every call, and
    the patch keeps those kernels on the configs FLA main uses there. Every training process imports it before FLA
    (patches/README.md) and prints a `[fla-guard]` line.