[Quantization] Add compressed-tensors NVFP4 support

tests/quantization/test_compressed_tensors.py

@@ -14,9 +14,10 @@
 from tests.models.utils import check_logprobs_close
 from vllm.model_executor.layers.quantization.compressed_tensors.compressed_tensors import (  # noqa: E501
     CompressedTensors24, CompressedTensorsLinearMethod,
-    CompressedTensorsW4A16Fp4, CompressedTensorsW4A16Sparse24,
-    CompressedTensorsW8A8Fp8, CompressedTensorsW8A8Int8,
-    CompressedTensorsW8A16Fp8, CompressedTensorsWNA16)
+    CompressedTensorsW4A4Fp4, CompressedTensorsW4A16Fp4,
+    CompressedTensorsW4A16Sparse24, CompressedTensorsW8A8Fp8,
+    CompressedTensorsW8A8Int8, CompressedTensorsW8A16Fp8,
+    CompressedTensorsWNA16)
 from vllm.model_executor.layers.quantization.utils.w8a8_utils import (
     sparse_cutlass_supported)
 from vllm.platforms import current_platform
@@ -651,9 +652,13 @@ def check_model(model):
         assert output
 
 
-def test_compressed_tensors_nvfp4a16(vllm_runner):
-    # run weight only example
-    model = "nm-testing/TinyLlama-1.1B-Chat-v1.0-NVFP4A16"
+@pytest.mark.parametrize(
+    "args",
+    [("nm-testing/TinyLlama-1.1B-Chat-v1.0-NVFP4A16",
+      CompressedTensorsW4A16Fp4),
+     ("nm-testing/TinyLlama-1.1B-Chat-v1.0-NVFP4", CompressedTensorsW4A4Fp4)])
+def test_compressed_tensors_nvfp4(vllm_runner, args):
+    model, scheme = args
     with vllm_runner(model, enforce_eager=True) as llm:
 
         def check_model(model):
@@ -662,7 +667,7 @@ def check_model(model):
             qkv_proj = layer.self_attn.qkv_proj
             assert isinstance(qkv_proj.quant_method,
                               CompressedTensorsLinearMethod)
-            assert isinstance(qkv_proj.scheme, CompressedTensorsW4A16Fp4)
+            assert isinstance(qkv_proj.scheme, scheme)
             assert qkv_proj.scheme.group_size == 16
 
         llm.apply_model(check_model)

vllm/model_executor/layers/quantization/compressed_tensors/compressed_tensors.py

@@ -24,10 +24,10 @@
     CompressedTensorsMoEMethod)
 from vllm.model_executor.layers.quantization.compressed_tensors.schemes import (
     W4A16SPARSE24_SUPPORTED_BITS, WNA16_SUPPORTED_BITS, CompressedTensors24,
-    CompressedTensorsScheme, CompressedTensorsW4A16Fp4,
-    CompressedTensorsW4A16Sparse24, CompressedTensorsW8A8Fp8,
-    CompressedTensorsW8A8Int8, CompressedTensorsW8A16Fp8,
-    CompressedTensorsWNA16)
+    CompressedTensorsScheme, CompressedTensorsW4A4Fp4,
+    CompressedTensorsW4A16Fp4, CompressedTensorsW4A16Sparse24,
+    CompressedTensorsW8A8Fp8, CompressedTensorsW8A8Int8,
+    CompressedTensorsW8A16Fp8, CompressedTensorsWNA16)
 from vllm.model_executor.layers.quantization.compressed_tensors.utils import (
     find_matched_target, is_activation_quantization_format,
     should_ignore_layer)
@@ -218,6 +218,26 @@ def _check_scheme_supported(self,
         else:
             return False
 
+    def _is_fp4a4_nvfp4(self, weight_quant: BaseModel, input_quant: BaseModel):
+
+        if weight_quant is None or input_quant is None:
+            return False
+
+        is_tensor_group_quant = (weight_quant.strategy
+                                 == QuantizationStrategy.TENSOR_GROUP.value
+                                 and input_quant.strategy
+                                 == QuantizationStrategy.TENSOR_GROUP.value)
+        is_symmetric = weight_quant.symmetric and input_quant.symmetric
+
+        is_group_size_16 = (weight_quant.group_size == 16
+                            and input_quant.group_size == 16)
+        is_float_type = (weight_quant.type == QuantizationType.FLOAT
+                         and input_quant.type == QuantizationType.FLOAT.value)
+        is_4_bits = weight_quant.num_bits == 4 and input_quant.num_bits == 4
+
+        return (is_tensor_group_quant and is_float_type and is_4_bits
+                and is_group_size_16 and is_symmetric)
+
     def _is_fp4a16_nvfp4(self, weight_quant: BaseModel,
                          input_quant: BaseModel):
 
@@ -353,6 +373,9 @@ def _get_scheme_from_parts(
                     actorder=weight_quant.actorder)
 
         if is_activation_quantization_format(self.quant_format):
+            if self._is_fp4a4_nvfp4(weight_quant, input_quant):
+                return CompressedTensorsW4A4Fp4()
+
             if self._is_fp8_w8a8(weight_quant, input_quant):
                 is_fp8_w8a8_supported = self._check_scheme_supported(
                     CompressedTensorsW8A8Fp8.get_min_capability(), error=False)

vllm/model_executor/layers/quantization/compressed_tensors/schemes/__init__.py

@@ -2,6 +2,7 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 from .compressed_tensors_scheme import CompressedTensorsScheme
+from .compressed_tensors_w4a4_nvfp4 import CompressedTensorsW4A4Fp4
 from .compressed_tensors_w4a16_24 import (W4A16SPARSE24_SUPPORTED_BITS,
                                           CompressedTensorsW4A16Sparse24)
 from .compressed_tensors_w4a16_nvfp4 import CompressedTensorsW4A16Fp4
@@ -18,5 +19,6 @@
     "CompressedTensorsW8A16Fp8", "CompressedTensorsW4A16Sparse24",
     "CompressedTensorsW8A8Int8", "CompressedTensorsW8A8Fp8",
     "WNA16_SUPPORTED_BITS", "W4A16SPARSE24_SUPPORTED_BITS",
-    "CompressedTensors24", "CompressedTensorsW4A16Fp4"
+    "CompressedTensors24", "CompressedTensorsW4A16Fp4",
+    "CompressedTensorsW4A4Fp4"
 ]

vllm/model_executor/layers/quantization/compressed_tensors/schemes/compressed_tensors_w4a4_nvfp4.py

@@ -0,0 +1,178 @@
+# SPDX-License-Identifier: Apache-2.0
+from typing import Callable, Optional
+
+import torch
+from torch.nn.parameter import Parameter
+
+from vllm._custom_ops import (cutlass_scaled_fp4_mm,
+                              cutlass_scaled_mm_supports_fp4, scaled_fp4_quant)
+from vllm.logger import init_logger
+from vllm.model_executor.layers.quantization.compressed_tensors.schemes import (
+    CompressedTensorsScheme)
+from vllm.model_executor.layers.quantization.utils.nvfp4_emulation_utils import (  # noqa: E501
+    dequantize_to_dtype, ref_nvfp4_quant)
+from vllm.model_executor.parameter import (GroupQuantScaleParameter,
+                                           ModelWeightParameter,
+                                           PerTensorScaleParameter)
+from vllm.platforms import current_platform
+
+logger = init_logger(__name__)
+
+__all__ = ["CompressedTensorsW4A4Fp4"]
+
+
+def cutlass_fp4_supported() -> bool:
+    if not current_platform.is_cuda():
+        return False
+    capability_tuple = current_platform.get_device_capability()
+    capability = -1 if capability_tuple is None else capability_tuple.to_int()
+    return cutlass_scaled_mm_supports_fp4(capability)
+
+
+class CompressedTensorsW4A4Fp4(CompressedTensorsScheme):
+
+    def __init__(self):
+        self.group_size = 16
+        self.cutlass_nvfp4_supported = cutlass_fp4_supported()
+        if not self.cutlass_nvfp4_supported:
+            logger.warning("Current platform does not support cutlass NVFP4."
+                           " Running emulations.")
+
+    @classmethod
+    def get_min_capability(cls) -> int:
+        # dont restrict as emulations
+        return 80
+
+    def run_nvfp4_emulations(self, x: torch.Tensor, layer):
+        x_m, x_k = x.shape
+        output_dtype = x.dtype
+
+        # quantize input to (FP4 and interleaved block scale)
+        x_fp4, x_blockscale = ref_nvfp4_quant(x, layer.input_global_scale,
+                                              self.group_size)
+
+        # dequantize input
+        x_fp4 = x_fp4.reshape(x_m, x_k // self.group_size, self.group_size)
+        x_blockscale = x_blockscale.unsqueeze(-1) / layer.input_global_scale
+        x_dq = (x_fp4 * x_blockscale).reshape(x_m, x_k).to(output_dtype)
+        del x_fp4, x_blockscale
+
+        # dequantize weight
+        w_fp4 = layer.weight.data.view(torch.uint8)
+        w_blockscale = layer.weight_scale_swizzled.data
+        w_global_scale = layer.weight_global_scale
+        w_dq = dequantize_to_dtype(w_fp4, w_blockscale, w_global_scale,
+                                   output_dtype, x.device, self.group_size)
+
+        # matmul
+        out = torch.matmul(x_dq, w_dq.t())
+        del w_dq, x_dq
+        return out
+
+    def create_weights(self, layer: torch.nn.Module,
+                       output_partition_sizes: list[int],
+                       input_size_per_partition: int,
+                       params_dtype: torch.dtype, weight_loader: Callable,
+                       **kwargs):
+        output_size_per_partition = sum(output_partition_sizes)
+        layer.logical_widths = output_partition_sizes
+        layer.input_size_per_partition = input_size_per_partition
+        layer.output_size_per_partition = output_size_per_partition
+
+        # Weight
+        weight = ModelWeightParameter(data=torch.empty(
+            sum(output_partition_sizes),
+            input_size_per_partition // 2,
+            dtype=torch.uint8),
+                                      input_dim=1,
+                                      output_dim=0,
+                                      weight_loader=weight_loader)
+        layer.register_parameter("weight_packed", weight)
+
+        # Global Weight Scale
+        weight_global_scale = PerTensorScaleParameter(
+            data=torch.empty(len(output_partition_sizes), dtype=torch.float32),
+            weight_loader=weight_loader)
+        layer.register_parameter("weight_global_scale", weight_global_scale)
+
+        # Per Group Weight Scale
+        weight_scale = GroupQuantScaleParameter(data=torch.empty(
+            sum(output_partition_sizes),
+            input_size_per_partition // self.group_size,
+            dtype=torch.float8_e4m3fn,
+        ),
+                                                input_dim=1,
+                                                output_dim=0,
+                                                weight_loader=weight_loader)
+
+        layer.register_parameter("weight_scale", weight_scale)
+
+        input_global_scale = PerTensorScaleParameter(
+            data=torch.empty(len(output_partition_sizes), dtype=torch.float32),
+            weight_loader=weight_loader)
+        layer.register_parameter("input_global_scale", input_global_scale)
+
+    def swizzle_blockscale(self, scale: torch.tensor):
+        assert (scale.dtype == torch.float8_e4m3fn)
+        # Pad and blockwise interleave weight_scale
+        scale_ndim = scale.ndim
+        if scale.ndim == 2:
+            scale = scale.unsqueeze(0)
+        assert scale.ndim == 3
+        B, M, K = scale.shape
+        round_up_multiple = lambda x, m: (x + m - 1) // m * m
+        M_padded = round_up_multiple(M, 128)
+        K_padded = round_up_multiple(K, 4)
+        padded_scale = torch.zeros((B, M_padded, K_padded), dtype=scale.dtype)
+        padded_scale[:B, :M, :K] = scale
+        batches, rows, cols = padded_scale.shape
+        assert rows % 128 == 0
+        assert cols % 4 == 0
+        padded_scale = padded_scale.reshape(batches, rows // 128, 4, 32,
+                                            cols // 4, 4)
+        swizzled_scale = padded_scale.permute((0, 1, 4, 3, 2, 5))
+        swizzled_scale = swizzled_scale.contiguous().cuda()
+        return (swizzled_scale.reshape(M, K)
+                if scale_ndim == 2 else swizzled_scale.reshape(B, M, K))
+
+    def process_weights_after_loading(self, layer) -> None:
+
+        global_input_scale = layer.input_global_scale.max().to(torch.float32)
+        layer.input_global_scale = Parameter(global_input_scale,
+                                             requires_grad=False)
+
+        layer.weight_global_scale = Parameter(
+            layer.weight_global_scale.max().to(torch.float32),
+            requires_grad=False)
+
+        swizzled_weight_scale = self.swizzle_blockscale(layer.weight_scale)
+        layer.weight_scale_swizzled = Parameter(swizzled_weight_scale,
+                                                requires_grad=False)
+
+        # required by cutlass kernel; need Parameter, not ModelWeightParameter
+        layer.weight = Parameter(layer.weight_packed.data, requires_grad=False)
+
+        if self.cutlass_nvfp4_supported:
+            layer.alpha = Parameter(layer.input_global_scale *
+                                    layer.weight_global_scale,
+                                    requires_grad=False)
+
+    def apply_weights(self,
+                      layer: torch.nn.Module,
+                      x: torch.Tensor,
+                      bias: Optional[torch.Tensor] = None) -> torch.Tensor:
+
+        if self.cutlass_nvfp4_supported:
+            output_dtype = x.dtype
+            output_shape = [x.shape[0], layer.weight.shape[0]]
+
+            # quantize BF16 or FP16 to (FP4 and interleaved block scale)
+            x_fp4, x_blockscale = scaled_fp4_quant(x, layer.input_global_scale)
+
+            out = cutlass_scaled_fp4_mm(x_fp4, layer.weight, x_blockscale,
+                                        layer.weight_scale_swizzled,
+                                        1 / layer.alpha, output_dtype)
+            if bias is not None:
+                out = out + bias
+            return out.view(*output_shape)
+        return self.run_nvfp4_emulations(x, layer)

vllm/model_executor/layers/quantization/compressed_tensors/utils.py

@@ -15,6 +15,7 @@ def is_activation_quantization_format(format: str) -> bool:
         CompressionFormat.naive_quantized.value,
         CompressionFormat.int_quantized.value,
         CompressionFormat.float_quantized.value,
+        CompressionFormat.nvfp4_pack_quantized.value
     ]
     return format in _ACTIVATION_QUANTIZATION_FORMATS
 

vllm/model_executor/layers/quantization/utils/nvfp4_emulation_utils.py

@@ -2,10 +2,11 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 import torch
 
-__all__ = [
-    "break_fp4_bytes",
-    "dequantize_to_dtype",
-]
+from vllm.scalar_type import scalar_types
+
+__all__ = ["break_fp4_bytes", "dequantize_to_dtype", "ref_nvfp4_quant"]
+
+FLOAT4_E2M1_MAX = scalar_types.float4_e2m1f.max()
 
 kE2M1ToFloat = torch.tensor([0., 0.5, 1., 1.5, 2., 3., 4., 6.],
                             dtype=torch.float32)
@@ -60,3 +61,44 @@ def dequantize_to_dtype(tensor_fp4,
     # scale the tensor
     out = (tensor_f32 * tensor_sf_dtype.unsqueeze(-1)).reshape(m, k)
     return out.to(dtype)
+
+
+def get_reciprocal(x):
+    if isinstance(x, torch.Tensor):
+        return torch.where(x == 0, torch.tensor(0.0, dtype=x.dtype), 1.0 / x)
+    elif isinstance(x, (float, int)):
+        return 0.0 if x == 0 else 1.0 / x
+    else:
+        raise TypeError("Input must be a float, int, or a torch.Tensor.")
+
+
+def cast_to_fp4(x):
+    sign = torch.sign(x)
+    x = torch.abs(x)
+    x[(x >= 0.0) & (x <= 0.25)] = 0.0
+    x[(x > 0.25) & (x < 0.75)] = 0.5
+    x[(x >= 0.75) & (x <= 1.25)] = 1.0
+    x[(x > 1.25) & (x < 1.75)] = 1.5
+    x[(x >= 1.75) & (x <= 2.5)] = 2.0
+    x[(x > 2.5) & (x < 3.5)] = 3.0
+    x[(x >= 3.5) & (x <= 5.0)] = 4.0
+    x[x > 5.0] = 6.0
+    return x * sign
+
+
+def ref_nvfp4_quant(x, global_scale, block_size):
+    assert global_scale.dtype == torch.float32
+    assert x.ndim == 2
+    m, n = x.shape
+    x = torch.reshape(x, (m, n // block_size, block_size))
+    vec_max = torch.max(torch.abs(x), dim=-1,
+                        keepdim=True)[0].to(torch.float32)
+    scale = global_scale * (vec_max * get_reciprocal(FLOAT4_E2M1_MAX))
+    scale = torch.clamp(scale, max=448, min=-448)
+    scale = scale.to(torch.float8_e4m3fn).to(torch.float32)
+    output_scale = get_reciprocal(scale * get_reciprocal(global_scale))
+
+    scaled_x = x.to(torch.float32) * output_scale
+    clipped_x = torch.clamp(scaled_x, -6.0, 6.0).reshape(m, n)
+    # both outputs are float32
+    return cast_to_fp4(clipped_x), scale.squeeze(-1)