Step-3.7-Flash W8A8 (AMD Quark → compressed-tensors)

Symmetric INT8 weights (per-channel) with INT8 dynamic per-token activations.

  • Base model: Step-3.7-Flash (multimodal Step3p7ForConditionalGeneration, 196B total / A11B sparse MoE, 288 routed experts top-8)
  • Quantization tool: AMD Quark 0.11.2 (int8, file2file), then losslessly repacked to the compressed-tensors format so that vLLM can load it.
  • Calibration: weight-only PTQ (RTN), no activation calibration. Activations are quantized dynamically per-token at inference time (no calibration needed).
  • Excluded from quantization: lm_head, MoE router (moe.gate, router_bias), share_expert, self_attn.g_proj, dense layers 0-2, MTP layers 45-47, and the full vision tower.

Usage (vLLM)

vllm serve <this-repo> --trust-remote-code --tensor-parallel-size 2 --enable-expert-parallel

NOTE: vLLM gates INT8 MoE behind current_platform.is_cuda(), which excludes ROCm. The Triton INT8 MoE kernel actually runs fine on MI355X; patch fused_moe/experts/triton_moe.py to force device_supports_int8 = True before launching.

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