Marlin24 Compressor (vllm-project#77)

* add marlin compressor

* full implementation running

* save meta matrix

* fix type

* change axis we pack on

* debug

* fix offset

* fix scale shape

* cast dtype

* cleanup

* fix

* avoid extra transpose

* add uncompressed weights

* unit tests

* cleanup

* Update src/compressed_tensors/compressors/marlin_24.py

Co-authored-by: dbogunowicz <97082108+dbogunowicz@users.noreply.github.com>

* Update src/compressed_tensors/compressors/marlin_24.py

Co-authored-by: dbogunowicz <97082108+dbogunowicz@users.noreply.github.com>

* style

* move helper fn

---------

Co-authored-by: dbogunowicz <97082108+dbogunowicz@users.noreply.github.com>

src/compressed_tensors/compressors/__init__.py

@@ -18,6 +18,7 @@
 from .dense import DenseCompressor
 from .helpers import load_compressed, save_compressed, save_compressed_model
 from .int_quantized import IntQuantizationCompressor
-from .model_compressor import ModelCompressor
+from .marlin_24 import Marlin24Compressor
+from .model_compressor import ModelCompressor, map_modules_to_quant_args
 from .pack_quantized import PackedQuantizationCompressor
 from .sparse_bitmask import BitmaskCompressor, BitmaskTensor

src/compressed_tensors/compressors/marlin_24.py

@@ -0,0 +1,250 @@
+# Copyright (c) 2021 - present / Neuralmagic, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+from typing import Dict, Generator, Tuple
+
+import numpy as np
+import torch
+from compressed_tensors.compressors import Compressor
+from compressed_tensors.compressors.utils import (
+    get_permutations_24,
+    sparse_semi_structured_from_dense_cutlass,
+    tensor_follows_mask_structure,
+)
+from compressed_tensors.config import CompressionFormat
+from compressed_tensors.quantization import QuantizationArgs, QuantizationStrategy
+from compressed_tensors.quantization.lifecycle.forward import quantize
+from compressed_tensors.utils import is_quantization_param, merge_names
+from torch import Tensor
+from tqdm import tqdm
+
+
+_LOGGER: logging.Logger = logging.getLogger(__name__)
+
+
+@Compressor.register(name=CompressionFormat.marlin_24.value)
+class Marlin24Compressor(Compressor):
+    """
+    Compresses a quantized model with 2:4 sparsity structure for inference with the
+    Marlin24 kernel. Decompression is not implemented for this compressor.
+    """
+
+    COMPRESSION_PARAM_NAMES = ["weight_packed", "scale_packed", "meta"]
+
+    @staticmethod
+    def validate_quant_compatability(
+        model_quant_args: Dict[str, QuantizationArgs]
+    ) -> bool:
+        """
+        Checks if every quantized module in the model is compatible with Marlin24
+        compression. Quantization must be channel or group strategy with group_size
+        of 128. Only symmetric quantization is supported
+
+        :param model_quant_args: dictionary of mapping module names to their
+            quantization configuration
+        :return: True if all modules are compatible with Marlin24 compression, raises
+            a ValueError otherwise
+        """
+        for name, quant_args in model_quant_args.items():
+            strategy = quant_args.strategy
+            group_size = quant_args.group_size
+            symmetric = quant_args.symmetric
+            if (
+                strategy is not QuantizationStrategy.GROUP
+                and strategy is not QuantizationStrategy.CHANNEL
+            ):
+                raise ValueError(
+                    f"Marlin24 Compressor is only valid for group and channel "
+                    f"quantization strategies, got {strategy} in {name}"
+                )
+
+            if group_size is not None and group_size != 128:
+                raise ValueError(
+                    f"Marlin24 Compressor is only valid for group size 128, "
+                    f"got {group_size} in {name}"
+                )
+
+            if not symmetric:
+                raise ValueError(
+                    f"Marlin24 Compressor is only valid for symmetric quantzation, "
+                    f"got symmetric={symmetric} in {name}"
+                )
+
+        return True
+
+    @staticmethod
+    def validate_sparsity_structure(name: str, weight: Tensor) -> bool:
+        """
+        Checks if a tensor fits the required 2:4 sparsity structure
+
+        :param name: name of the tensor to check
+        :param weight: tensor to check for sparsity structure
+        :return: True if all rows match the 2:4 sparsity structure, raises
+            ValueError otherwise
+        """
+
+        if not tensor_follows_mask_structure(weight):
+            raise ValueError(
+                "Marlin24 Compressor is only compatible with weights that have "
+                f"a 2:4 sparsity structure. Found segments in {name} "
+                "that do not match the expected structure."
+            )
+
+        return True
+
+    def compress(
+        self,
+        model_state: Dict[str, Tensor],
+        model_quant_args: Dict[str, QuantizationArgs],
+        **kwargs,
+    ) -> Dict[str, Tensor]:
+        """
+        Compresses a quantized state_dict with 2:4 sparsity structure for inference
+        with the Marlin24 kernel
+
+        :param model_state: state dict of uncompressed model
+        :param model_quant_args: quantization args for each quantized weight, needed for
+           quantize function to calculate bit depth
+        :return: compressed state dict
+        """
+        self.validate_quant_compatability(model_quant_args)
+
+        compressed_dict = {}
+        weight_suffix = ".weight"
+        _LOGGER.debug(
+            f"Compressing model with {len(model_state)} parameterized layers..."
+        )
+
+        for name, value in tqdm(model_state.items(), desc="Compressing model"):
+            if name.endswith(weight_suffix):
+                prefix = name[: -(len(weight_suffix))]
+                scale = model_state.get(merge_names(prefix, "weight_scale"), None)
+                zp = model_state.get(merge_names(prefix, "weight_zero_point"), None)
+                if scale is not None:  # weight is quantized, compress it
+
+                    # Marlin24 kernel requires float16 inputs
+                    scale = scale.to(torch.float16)
+                    value = value.to(torch.float16)
+
+                    # quantize weight, keeping it as a float16 for now
+                    quant_args = model_quant_args[prefix]
+                    value = quantize(
+                        x=value, scale=scale, zero_point=zp, args=quant_args
+                    )
+
+                    # compress based on sparsity structure
+                    self.validate_sparsity_structure(prefix, value)
+                    value, meta = compress_weight_24(value)
+                    meta = meta.cpu()
+
+                    # Marlin24 kernel expects input dim first
+                    value = value.t().contiguous().cpu()
+                    scale = scale.t().contiguous().cpu()
+                    og_weight_shape = value.shape
+
+                    # Marlin24 kernel expects unsigned values, shift zero-point
+                    value += (1 << quant_args.num_bits) // 2
+
+                    # pack quantized weight and scale
+                    value = pack_weight_24(value, quant_args)
+                    packed_scale = pack_scales_24(scale, quant_args, og_weight_shape)
+                    meta = meta.resize_(meta.shape[1] // 2, meta.shape[0] * 2)
+
+                    # save compressed values
+                    compressed_dict[merge_names(prefix, "scale_packed")] = packed_scale
+                    compressed_dict[merge_names(prefix, "weight_packed")] = value
+                    compressed_dict[merge_names(prefix, "meta")] = meta
+                    continue
+
+            if not is_quantization_param(name):
+                # export unquantized parameters without modifying
+                compressed_dict[name] = value.to("cpu")
+
+        return compressed_dict
+
+    def decompress(
+        self, path_to_model_or_tensors: str, device: str = "cpu"
+    ) -> Generator[Tuple[str, Tensor], None, None]:
+        raise NotImplementedError(
+            "Decompression is not implemented for the Marlin24 Compressor."
+        )
+
+
+def compress_weight_24(weight: Tensor):
+    weight = weight.contiguous()
+    w_comp, meta = sparse_semi_structured_from_dense_cutlass(weight)
+    w_comp = w_comp.contiguous()
+    return w_comp, meta
+
+
+def marlin_permute_weights(q_w, size_k, size_n, perm, tile):
+    assert q_w.shape == (size_k, size_n)
+    assert size_k % tile == 0, f"size_k = {size_k}, tile = {tile}"
+    assert size_n % tile == 0, f"size_k = {size_n}, tile = {tile}"
+
+    # Permute weights to 16x64 marlin tiles
+    q_w = q_w.reshape((size_k // tile, tile, size_n // tile, tile))
+    q_w = q_w.permute((0, 2, 1, 3))
+    q_w = q_w.reshape((size_k // tile, size_n * tile))
+
+    q_w = q_w.reshape((-1, perm.numel()))[:, perm].reshape(q_w.shape)
+
+    return q_w
+
+
+def pack_weight_24(
+    weight: Tensor,
+    quantization_args: QuantizationArgs,
+    tile: int = 16,
+):
+    size_k = weight.shape[0]
+    size_n = weight.shape[1]
+    num_bits = quantization_args.num_bits
+    pack_factor = 32 // num_bits
+
+    # Reshuffle to marlin_24 format
+    perm, _, _ = get_permutations_24(num_bits)
+    q_w = marlin_permute_weights(weight, size_k, size_n, perm, tile)
+
+    q_w = q_w.cpu().numpy().astype(np.uint32)
+
+    q_packed = np.zeros((q_w.shape[0], q_w.shape[1] // pack_factor), dtype=np.uint32)
+    for i in range(pack_factor):
+        q_packed |= q_w[:, i::pack_factor] << num_bits * i
+
+    q_packed = torch.from_numpy(q_packed.astype(np.int32))
+
+    return q_packed
+
+
+def pack_scales_24(scales, quantization_args, w_shape):
+    size_k = w_shape[0]
+    size_n = w_shape[1]
+    num_bits = quantization_args.num_bits
+
+    _, scale_perm_2_4, scale_perm_single_2_4 = get_permutations_24(num_bits)
+
+    if (
+        quantization_args.strategy is QuantizationStrategy.GROUP
+        and quantization_args.group_size < size_k
+    ):
+        scales = scales.reshape((-1, len(scale_perm_2_4)))[:, scale_perm_2_4]
+    else:  # channelwise
+        scales = scales.reshape((-1, len(scale_perm_single_2_4)))[
+            :, scale_perm_single_2_4
+        ]
+    scales = scales.reshape((-1, size_n)).contiguous()
+
+    return scales

src/compressed_tensors/compressors/model_compressor.py

@@ -45,7 +45,7 @@
 from transformers.file_utils import CONFIG_NAME
 
 
-__all__ = ["ModelCompressor"]
+__all__ = ["ModelCompressor", "map_modules_to_quant_args"]
 
 _LOGGER: logging.Logger = logging.getLogger(__name__)
 
@@ -190,7 +190,7 @@ def compress(
             state_dict = model.state_dict()
 
         compressed_state_dict = state_dict
-        quantized_modules_to_args = _get_weight_arg_mappings(model)
+        quantized_modules_to_args = map_modules_to_quant_args(model)
         if self.quantization_compressor is not None:
             compressed_state_dict = self.quantization_compressor.compress(
                 state_dict, model_quant_args=quantized_modules_to_args
@@ -269,7 +269,7 @@ def _replace_weights(self, dense_weight_generator, model):
             data_old.data = data_new.data
 
 
-def _get_weight_arg_mappings(model: Module) -> Dict:
+def map_modules_to_quant_args(model: Module) -> Dict:
     quantized_modules_to_args = {}
     for name, submodule in iter_named_leaf_modules(model):
         if is_module_quantized(submodule):

src/compressed_tensors/compressors/utils/__init__.py

@@ -0,0 +1,19 @@
+# Copyright (c) 2021 - present / Neuralmagic, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# flake8: noqa
+
+from .helpers import *
+from .permutations_24 import *
+from .semi_structured_conversions import *

src/compressed_tensors/compressors/utils/helpers.py

@@ -0,0 +1,43 @@
+# Copyright (c) 2021 - present / Neuralmagic, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import torch
+
+
+__all__ = ["tensor_follows_mask_structure"]
+
+
+def tensor_follows_mask_structure(tensor, mask: str = "2:4") -> bool:
+    """
+    :param tensor: tensor to check
+    :param mask: mask structure to check for, in the format "n:m"
+    :return: True if the tensor follows the mask structure, False otherwise.
+        Note, some weights can incidentally be zero, so we check for
+        atleast n zeros in each chunk of size m
+    """
+
+    n, m = tuple(map(int, mask.split(":")))
+    # Reshape the tensor into chunks of size m
+    tensor = tensor.view(-1, m)
+
+    # Count the number of zeros in each chunk
+    zero_counts = (tensor == 0).sum(dim=1)
+
+    # Check if the number of zeros in each chunk atleast n
+    # Greater than sign is needed as some weights can incidentally
+    # be zero
+    if not torch.all(zero_counts >= n).item():
+        raise ValueError()
+
+    return True