Refactor based on recent torch tensor view support (#1816)

Summary:
Pull Request resolved: #1816

torch.view recently added reinterpret_cast dtype support:

https://pytorch.org/docs/stable/generated/torch.Tensor.view.html

Previously we have to rely on numpy, which introduces the extra H2D/D2H overhead.

Reviewed By: sryap

Differential Revision: D46585543

fbshipit-source-id: a1d4e792e61c15c71bb36d47a574d2c052e0a02f

fbgemm_gpu/fbgemm_gpu/split_embedding_inference_converter.py

@@ -9,12 +9,14 @@
 
 import logging
 import math
-from typing import Optional, Tuple
+from typing import cast, Optional, Tuple
 
 import numpy as np
 import torch
 
 from fbgemm_gpu.split_embedding_configs import QuantizationConfig, SparseType
+
+from fbgemm_gpu.split_embedding_utils import FP8QuantizationConfig, quantize_embs
 from fbgemm_gpu.split_table_batched_embeddings_ops_common import EmbeddingLocation
 from fbgemm_gpu.split_table_batched_embeddings_ops_inference import (
     IntNBitTableBatchedEmbeddingBagsCodegen,
@@ -93,59 +95,8 @@ def _get_quantization_config(self, name):
     def _quantize_embs(
         self, weight: Tensor, weight_ty: SparseType
     ) -> Tuple[Tensor, Optional[Tensor]]:
-        if weight_ty == SparseType.FP32:
-            q_weight = weight.float()
-            # FIXME: How to view the PyTorch Tensor as a different type (e.g., uint8)
-            # Here it uses numpy and it will introduce DtoH/HtoD overhead.
-            res_weight = torch.tensor(
-                q_weight.cpu().numpy().view(np.uint8)
-            ).contiguous()
-            return (res_weight, None)
-
-        elif weight_ty == SparseType.FP16:
-            q_weight = weight.half()
-            res_weight = torch.tensor(
-                q_weight.cpu().numpy().view(np.uint8)
-            ).contiguous()
-            return (res_weight, None)
-
-        elif weight_ty == SparseType.FP8:
-            # Output tensor is already in uint8
-            q_weight = torch.ops.fbgemm.FloatToHFP8Quantized(
-                weight.float(),
-                self._get_quantization_config("exponent_bits"),
-                self._get_quantization_config("exponent_bias"),
-                self._get_quantization_config("max_position"),
-            )
-            return (q_weight, None)
-
-        elif weight_ty == SparseType.INT8:
-            q_weight = torch.ops.fbgemm.FloatToFused8BitRowwiseQuantized(weight)
-            res_weight = torch.tensor(q_weight[:, :-8].cpu().numpy().view(np.uint8))
-            res_scale_shift = torch.tensor(
-                q_weight[:, -8:]
-                .contiguous()
-                .cpu()
-                .numpy()
-                .view(np.float32)
-                .astype(np.float16)
-                .view(np.uint8)
-            )  # [-4, -2]: scale; [-2:]: bias
-            return (res_weight, res_scale_shift)
-
-        elif weight_ty == SparseType.INT4 or weight_ty == SparseType.INT2:
-            q_weight = torch.ops.fbgemm.FloatToFusedNBitRowwiseQuantizedSBHalf(
-                weight,
-                bit_rate=weight_ty.bit_rate(),
-            )
-            res_weight = torch.tensor(q_weight[:, :-4].cpu().numpy().view(np.uint8))
-            res_scale_shift = torch.tensor(
-                q_weight[:, -4:].contiguous().cpu().numpy().view(np.uint8)
-            )  # [-4, -2]: scale; [-2:]: bias
-            return (res_weight, res_scale_shift)
-
-        else:
-            raise RuntimeError("Unsupported SparseType: {}".format(weight_ty))
+        fp8_quant_config = cast(FP8QuantizationConfig, self.quantization_config)
+        return quantize_embs(weight, weight_ty, fp8_quant_config)
 
     def _process_split_embs(self, model: nn.Module) -> None:
         for name, child in model.named_children():

fbgemm_gpu/fbgemm_gpu/split_embedding_utils.py

@@ -320,20 +320,15 @@ def quantize_embs(
     weight_ty: SparseType,
     fp8_config: Optional[FP8QuantizationConfig] = None,
 ) -> Tuple[torch.Tensor, Optional[torch.Tensor]]:
-    assert (
-        weight.dtype == torch.float
-    ), "The input tensor for quantize_embs function needs to be float tensor"
     weight = weight.detach()
     if weight_ty == SparseType.FP32:
         q_weight = weight.float()
-        # FIXME: How to view the PyTorch Tensor as a different type (e.g., uint8)
-        # Here it uses numpy and it will introduce DtoH/HtoD overhead.
-        res_weight = torch.tensor(q_weight.cpu().numpy().view(np.uint8)).contiguous()
+        res_weight = q_weight.view(torch.uint8)
         return (res_weight, None)
 
     elif weight_ty == SparseType.FP16:
         q_weight = weight.half()
-        res_weight = torch.tensor(q_weight.cpu().numpy().view(np.uint8)).contiguous()
+        res_weight = q_weight.view(torch.uint8)
         return (res_weight, None)
 
     elif weight_ty == SparseType.FP8:
@@ -352,15 +347,9 @@ def quantize_embs(
         # for alignment if embedding dimension is not a multiple of 4:
         # https://fburl.com/code/z009xsy6
         q_weight = torch.ops.fbgemm.FloatToFused8BitRowwiseQuantized(weight)
-        res_weight = torch.tensor(q_weight[:, :-8].cpu().numpy().view(np.uint8))
+        res_weight = q_weight[:, :-8].view(torch.uint8)
         res_scale_shift = torch.tensor(
-            q_weight[:, -8:]
-            .contiguous()
-            .cpu()
-            .numpy()
-            .view(np.float32)
-            .astype(np.float16)
-            .view(np.uint8)
+            q_weight[:, -8:].view(torch.float32).to(torch.float16).view(torch.uint8)
         )  # [-4, -2]: scale; [-2:]: bias
         return (res_weight, res_scale_shift)
 
@@ -371,9 +360,9 @@ def quantize_embs(
             weight,
             bit_rate=weight_ty.bit_rate(),
         )
-        res_weight = torch.tensor(q_weight[:, :-4].cpu().numpy().view(np.uint8))
+        res_weight = q_weight[:, :-4].view(torch.uint8)
         res_scale_shift = torch.tensor(
-            q_weight[:, -4:].contiguous().cpu().numpy().view(np.uint8)
+            q_weight[:, -4:].view(torch.uint8)
         )  # [-4, -2]: scale; [-2:]: bias
         return (res_weight, res_scale_shift)
 
@@ -392,60 +381,54 @@ def dequantize_embs(
     assert (
         weights.dtype == torch.uint8
     ), "The input tensor for dequantize_embs function needs to be byte tensor"
-    np_weights = weights.contiguous().cpu().numpy()
+    th_weights = weights
 
     if scale_shift is not None:
-        np_scale_shift: np.ndarray = (
-            scale_shift.cpu().contiguous().numpy().view(np.float16).astype(np.float32)
-        )
+        th_scale_shift: torch.Tensor = scale_shift.view(torch.float16).to(torch.float32)
 
     if weight_ty == SparseType.INT4:
-        (E, D_2) = np_weights.shape
+        (E, D_2) = th_weights.shape
         D = D_2 * 2
 
-        def comp(i: int) -> np.ndarray:
-            subs = np_weights.view(np.uint8) >> (i * 4)
+        def comp(i: int) -> torch.Tensor:
+            subs = th_weights.view(torch.uint8) >> (i * 4)
             sub_mask = subs & 0xF
-            result = sub_mask.astype(np.float32) * np_scale_shift[:, 0].reshape(
+            result = sub_mask.to(torch.float32) * th_scale_shift[:, 0].reshape(
                 -1, 1
-            ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(
-                np.float32
-            )
-            return result.astype(np.float32)
+            ).to(torch.float32) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
+            return result.to(torch.float32)
 
         comps = [comp(i) for i in range(2)]
-        comps = np.stack(comps)
-        comps = comps.transpose(1, 2, 0)
+        comps = torch.stack(comps)
+        comps = comps.permute(1, 2, 0)
         comps = comps.reshape(E, D)
         return to_device(torch.tensor(comps), use_cpu)
 
     elif weight_ty == SparseType.INT2:
-        (E, D_4) = np_weights.shape
+        (E, D_4) = th_weights.shape
         D = D_4 * 4
 
         # pyre-fixme[53]: Captured variable `scale_shift` is not annotated.
         # pyre-fixme[53]: Captured variable `weights` is not annotated.
-        def comp(i: int) -> np.ndarray:
-            subs = np_weights.view(np.uint8) >> (i * 2)
+        def comp(i: int) -> torch.Tensor:
+            subs = th_weights.view(torch.uint8) >> (i * 2)
             sub_mask = subs & 0x3
-            result = sub_mask.astype(np.float32) * np_scale_shift[:, 0].reshape(
+            result = sub_mask.to(torch.float32) * th_scale_shift[:, 0].reshape(
                 -1, 1
-            ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(
-                np.float32
-            )
-            return result.astype(np.float32)
+            ).to(torch.float32) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
+            return result.to(torch.float32)
 
         comps = [comp(i) for i in range(4)]
-        comps = np.stack(comps)
-        comps = comps.transpose(1, 2, 0)
+        comps = torch.stack(comps)
+        comps = comps.permute(1, 2, 0)
         comps = comps.reshape(E, D)
         return to_device(torch.tensor(comps), use_cpu)
 
     elif weight_ty == SparseType.INT8:
-        (E, D) = np_weights.shape
-        comps = np_weights.astype(np.float32) * np_scale_shift[:, 0].reshape(
-            -1, 1
-        ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(np.float32)
+        (E, D) = th_weights.shape
+        comps = th_weights.to(torch.float32) * th_scale_shift[:, 0].reshape(-1, 1).to(
+            torch.float32
+        ) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
         return to_device(torch.tensor(comps), use_cpu)
 
     elif weight_ty == SparseType.FP8:
@@ -461,12 +444,12 @@ def comp(i: int) -> np.ndarray:
 
     elif weight_ty == SparseType.FP16:
         assert scale_shift is None
-        comps = np_weights.view(np.half)
+        comps = th_weights.view(torch.half)
         return to_device(torch.tensor(comps), use_cpu)
 
     elif weight_ty == SparseType.FP32:
         assert scale_shift is None
-        comps = np_weights.view(np.float32)
+        comps = th_weights.view(torch.float32)
         # pyre-fixme[7]: Expected `Tensor` but got implicit return value of `None`.
         return to_device(torch.tensor(comps), use_cpu)
 
@@ -482,61 +465,57 @@ def fake_quantize_embs(
     assert (
         weights.dtype == torch.uint8
     ), "The input tensor for dequantize_embs function needs to be byte tensor"
-    np_weights = weights.contiguous().cpu().numpy()
+    th_weights = weights
 
     if scale_shift is not None:
-        np_scale_shift: np.ndarray = (
-            scale_shift.cpu().contiguous().numpy().view(np.float16).astype(np.float32)
+        th_scale_shift: torch.Tensor = (
+            scale_shift.contiguous().view(torch.float16).to(torch.float32)
         )
 
     if weight_ty == SparseType.INT4:
-        (E, D_2) = np_weights.shape
+        (E, D_2) = th_weights.shape
         D = D_2 * 2
 
-        def comp(i: int) -> np.ndarray:
-            subs = np_weights.view(np.uint8) >> (i * 4)
+        def comp(i: int) -> torch.Tensor:
+            subs = th_weights.view(torch.uint8) >> (i * 4)
             sub_mask = subs & 0xF
-            result = sub_mask.astype(np.float32) * np_scale_shift[:, 0].reshape(
+            result = sub_mask.to(torch.float32) * th_scale_shift[:, 0].reshape(
                 -1, 1
-            ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(
-                np.float32
-            )
-            return result.astype(np.float32)
+            ).to(torch.float32) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
+            return result.to(torch.float32)
 
         comps = [comp(i) for i in range(2)]
-        comps = np.stack(comps)
-        comps = comps.transpose(1, 2, 0)
+        comps = torch.stack(comps)
+        comps = comps.permute(1, 2, 0)
         comps = comps.reshape(E, D)
-        dequant_weights.copy_(to_device(torch.tensor(comps), use_cpu))
+        dequant_weights.copy_(to_device(comps, use_cpu))
 
     elif weight_ty == SparseType.INT2:
-        (E, D_4) = np_weights.shape
+        (E, D_4) = th_weights.shape
         D = D_4 * 4
 
         # pyre-fixme[53]: Captured variable `scale_shift` is not annotated.
         # pyre-fixme[53]: Captured variable `weights` is not annotated.
-        def comp(i: int) -> np.ndarray:
-            subs = np_weights.view(np.uint8) >> (i * 2)
+        def comp(i: int) -> torch.Tensor:
+            subs = th_weights.view(torch.uint8) >> (i * 2)
             sub_mask = subs & 0x3
-            result = sub_mask.astype(np.float32) * np_scale_shift[:, 0].reshape(
+            result = sub_mask.to(torch.float32) * th_scale_shift[:, 0].reshape(
                 -1, 1
-            ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(
-                np.float32
-            )
-            return result.astype(np.float32)
+            ).to(torch.float32) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
+            return result.to(torch.float32)
 
         comps = [comp(i) for i in range(4)]
-        comps = np.stack(comps)
-        comps = comps.transpose(1, 2, 0)
+        comps = torch.stack(comps)
+        comps = comps.permute(1, 2, 0)
         comps = comps.reshape(E, D)
-        dequant_weights.copy_(to_device(torch.tensor(comps), use_cpu))
+        dequant_weights.copy_(to_device(comps, use_cpu))
 
     elif weight_ty == SparseType.INT8:
-        (E, D) = np_weights.shape
-        comps = np_weights.astype(np.float32) * np_scale_shift[:, 0].reshape(
-            -1, 1
-        ).astype(np.float32) + np_scale_shift[:, 1].reshape(-1, 1).astype(np.float32)
-        dequant_weights.copy_(to_device(torch.tensor(comps), use_cpu))
+        (E, D) = th_weights.shape
+        comps = th_weights.to(torch.float32) * th_scale_shift[:, 0].reshape(-1, 1).to(
+            torch.float32
+        ) + th_scale_shift[:, 1].reshape(-1, 1).to(torch.float32)
+        dequant_weights.copy_(to_device(comps, use_cpu))
 
     elif weight_ty == SparseType.FP8:
         assert fp8_config is not None
@@ -556,13 +535,13 @@ def comp(i: int) -> np.ndarray:
             fp8_config.get("exponent_bits"),
             fp8_config.get("exponent_bias"),
         )
-        dequant_weights.copy_(to_device(torch.tensor(comps), use_cpu))
+        dequant_weights.copy_(to_device(comps, use_cpu))
 
     elif weight_ty == SparseType.FP16:
         assert scale_shift is None
-        comps = dequant_weights.detach().half().cpu().numpy().view(np.uint8)
-        weights.copy_(torch.tensor(comps))
+        comps = dequant_weights.detach().half().view(torch.uint8)
+        weights.copy_(comps)
     elif weight_ty == SparseType.FP32:
         assert scale_shift is None
-        comps = dequant_weights.detach().float().cpu().numpy().view(np.uint8)
-        weights.copy_(torch.tensor(comps))
+        comps = dequant_weights.detach().float().view(torch.uint8)
+        weights.copy_(comps)