功能描述

将数据类型为int32的输入tensor打包为int4存放，每8个int4数据通过一个int32数据承载，并进行交叠排放。

接口原型

torch_npu.npu_convert_weight_to_int4pack(Tensor weight, int inner_k_tiles=0) -> Tensor

参数说明

weight : Device侧Tensor类型，输入的weight，数据格式支持ND、FRACTAL_NZ，数据类型支持INT32，不支持非连续的Tensor；维度支持2维，shape支持（k, n）, (n, k)，最后一维度需要8个元素对齐，元素的值需要在int4的表示范围内，即[-8, 7]。
inner_k_tiles：int类型，用于制定内部打包格式中，多少个K-tiles被打包在一起，默认值为0。预留参数，暂未使用。

输出说明

输出为Tensor类型，代表int4打包后的输出，数据类型为INT32，shape为（k, n/8）, (n, k/8)，数据格式支持ND。

约束说明

该接口仅在推理场景下使用。
该接口支持图模式（目前仅支持PyTorch 2.1版本）。

支持的型号

Atlas A2 训练系列产品/Atlas 800I A2 推理产品
Atlas A3 训练系列产品

调用示例

单算子模式调用

import torch
import torch_npu

m = 128
k = 64
n = 32
trans_weight = False

cpu_x = torch.randn((m, k), dtype=torch.float16)
if trans_weight:
    cpu_weight = torch.randint(low=-8, high=8, size=(n, k), dtype=torch.int32)
    cpu_antiquantscale = torch.randn((n, 1), dtype=torch.float16)
    cpu_antiquantoffset = torch.randn((n, 1), dtype=torch.float16)
else:
    cpu_weight = torch.randint(low=-8, high=8, size=(k, n), dtype=torch.int32)
    cpu_antiquantscale = torch.randn((1, n), dtype=torch.float16)
    cpu_antiquantoffset = torch.randn((1, n), dtype=torch.float16)

weight_int4 = torch_npu.npu_convert_weight_to_int4pack(cpu_weight.npu())

if trans_weight:
    cpu_weight = cpu_weight.transpose(-1, -2)
    weight_int4 = weight_int4.transpose(-1, -2)
    cpu_antiquantscale = cpu_antiquantscale.transpose(-1, -2)
    cpu_antiquantoffset = cpu_antiquantoffset.transpose(-1, -2)

npu_out = torch_npu.npu_weight_quant_batchmatmul(cpu_x.npu(), weight_int4.npu(), cpu_antiquantscale.npu(), cpu_antiquantoffset.npu())

图模式调用

import torch
import torch_npu
import  torchair
from torchair.configs.compiler_config import CompilerConfig
config = CompilerConfig()
npu_backend = torchair.get_npu_backend(compiler_config=config)

m = 16
k = 17
n = 72

trans_weight = False
is_weight_nz = False

cpu_x = torch.randn((m, k),dtype=torch.float16)
if trans_weight:
    cpu_weight = torch.randint(low=-8, high=8, size=(n, k) ,dtype=torch.int32)
    cpu_antiquantscale = torch.ones((n, 1),dtype=torch.float16)
    cpu_antiquantoffset = torch.zeros((n, 1),dtype=torch.float16)
else:
    cpu_weight = torch.randint(low=-8, high=8, size=(k, n) ,dtype=torch.int32)
    cpu_antiquantscale = torch.ones((1, n),dtype=torch.float16)
    cpu_antiquantoffset = torch.zeros((1, n),dtype=torch.float16)

npu_weight = cpu_weight.npu()
if is_weight_nz:
   # nd to fractal_nz
   npu_weight = torch_npu.npu_format_cast(npu_weight.npu(), 29)
# int32 to int4pack
weight_int4pack = torch_npu.npu_convert_weight_to_int4pack(npu_weight)

class MyModel(torch.nn.Module):
    def __init__(self):
        super().__init__()

    def forward(self, x, weight, antiquant_scale, antiquant_offset, quant_scale,quant_offset, bias, antiquant_group_size):
        if trans_weight:
            weight  = weight.transpose(-1, -2)
            antiquant_scale = antiquant_scale.transpose(-1, -2)
            antiquant_offset = antiquant_offset.transpose(-1, -2)
        return torch_npu.npu_weight_quant_batchmatmul(x, weight, antiquant_scale, antiquant_offset, quant_scale ,quant_offset, bias, antiquant_group_size)

cpu_model = MyModel()
model = cpu_model.npu()
model = torch.compile(cpu_model, backend=npu_backend, dynamic=True, fullgraph=True)

npu_out = model(cpu_x.npu(), weight_int4pack, cpu_antiquantscale.npu(), cpu_antiquantoffset.npu(), None, None, None, 0)