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wentao-ref
| Author | SHA1 | Date | |
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| 620ad799ba | |||
| f0756a5b25 | |||
| 6c5382d06e | |||
| e179b705e9 | |||
| 90978b2799 | |||
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@ -41,7 +41,6 @@ from vllm.model_executor.layers.quantization.base_config import (
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QuantizationConfig,
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QuantizeMethodBase,
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)
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from vllm.model_executor.layers.quantization.input_quant_fp8 import QuantFP8
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from vllm.model_executor.layers.quantization.kv_cache import BaseKVCacheMethod
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from vllm.model_executor.layers.quantization.utils.flashinfer_utils import (
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FlashinferMoeBackend,
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@ -94,11 +93,9 @@ from vllm.model_executor.utils import set_weight_attrs
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from vllm.platforms import current_platform
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from vllm.scalar_type import scalar_types
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from vllm.utils.deep_gemm import (
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fp8_gemm_nt,
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get_col_major_tma_aligned_tensor,
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is_deep_gemm_e8m0_used,
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is_deep_gemm_supported,
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should_use_deepgemm_for_fp8_linear,
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)
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from vllm.utils.flashinfer import has_flashinfer_moe
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from vllm.utils.import_utils import has_deep_gemm
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@ -546,83 +543,19 @@ class Fp8LinearMethod(LinearMethodBase):
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# if batch invariant mode is enabled, prefer DeepGEMM FP8 path
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# we will use BF16 dequant when DeepGEMM is not supported.
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if vllm_is_batch_invariant():
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# Call is_deep_gemm_supported() ahead of time for torch.compile
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# dynamo has trouble tracing through
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if self.block_quant and should_use_deepgemm_for_fp8_linear(
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torch.bfloat16, layer.weight, self.use_deep_gemm
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):
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# use group quant consistent with block size across K
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assert self.act_q_group_shape is not None
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q_input, input_scale = QuantFP8(
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False,
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self.act_q_group_shape,
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column_major_scales=True,
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)(x)
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output_2d = torch.empty(
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(q_input.shape[0], layer.weight.shape[0]),
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dtype=torch.bfloat16,
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device=q_input.device,
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)
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fp8_gemm_nt(
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(q_input, input_scale),
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(layer.weight, layer.weight_scale),
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output_2d,
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)
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if bias is not None:
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output_2d = output_2d + bias
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return output_2d
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# Dequantize FP8 weights to BF16
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weight_fp8 = layer.weight.to(torch.bfloat16)
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weight_scale = layer.weight_scale.to(torch.bfloat16)
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# Handle different quantization granularities
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if self.block_quant:
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# Block-wise quantization:
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# - Weight is NOT transposed, shape is [N, K] (output_size, input_size)
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# - Scale has shape [num_blocks_k, num_blocks_n] (TRANSPOSED!)
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assert self.weight_block_size is not None
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block_n, block_k = self.weight_block_size # Note: order is [N, K]
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N, K = weight_fp8.shape
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# determine expected number of blocks along N and K
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num_blocks_n = (N + block_n - 1) // block_n
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num_blocks_k = (K + block_k - 1) // block_k
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# scale layout may be [num_blocks_n, num_blocks_k]
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# or [num_blocks_k, num_blocks_n] depending on backend
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if weight_scale.dim() != 2:
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raise RuntimeError(
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f"FP8 block scale must be 2D, got {tuple(weight_scale.shape)}"
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)
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scale_rows, scale_cols = weight_scale.shape
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if (scale_rows, scale_cols) == (num_blocks_k, num_blocks_n):
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if num_blocks_n == num_blocks_k:
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# ambiguous square case, warn and skip transpose
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logger.warning(
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"Batch-invariant FP8: square block-scale %dx%d; "
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"skipping transpose to avoid misorientation.",
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scale_rows,
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scale_cols,
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)
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else:
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# clear KN -> transpose to NK
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weight_scale = weight_scale.t()
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# Expand scale to match weight dimensions
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# scale_expanded should have shape [N, K]
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scale_expanded = weight_scale.repeat_interleave(
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block_n, dim=0
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).repeat_interleave(block_k, dim=1)
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# Trim to exact weight size (in case of padding)
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scale_expanded = scale_expanded[:N, :K]
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weight_bf16 = weight_fp8 * scale_expanded
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return self.w8a8_block_fp8_linear.apply(
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input=x,
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weight=layer.weight,
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weight_scale=layer.weight_scale,
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input_scale=layer.input_scale,
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bias=bias,
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)
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else:
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# Per-tensor quantization: weight IS transposed to [K, N]
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# scale should be scalar or [1] or per-output-channel [N]
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# per-tensor/channel: dequant to BF16 and run GEMM
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weight_fp8 = layer.weight.to(torch.bfloat16)
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weight_scale = layer.weight_scale.to(torch.bfloat16)
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if weight_scale.numel() == 1:
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# Per-tensor: simple scalar multiplication
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weight_bf16 = weight_fp8 * weight_scale
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@ -641,16 +574,7 @@ class Fp8LinearMethod(LinearMethodBase):
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else:
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# Fallback
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weight_bf16 = weight_fp8 * weight_scale
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# For block quant, weight is [N, K], for per-tensor it's [K, N]
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# F.linear expects weight to be [N, K], so:
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if self.block_quant:
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# Already in correct shape [N, K]
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output = torch.nn.functional.linear(x, weight_bf16, bias)
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else:
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# Need to transpose back: [K, N] -> [N, K]
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output = torch.nn.functional.linear(x, weight_bf16.t(), bias)
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return output
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return torch.nn.functional.linear(x, weight_bf16.t(), bias)
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if self.use_marlin:
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return apply_fp8_marlin_linear(
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