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[doc] add shardformer support matrix/update tensor parallel documents (#4728)
* add compatibility matrix for shardformer doc * update tp doc
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@@ -60,82 +60,8 @@ $$
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## 使用
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为了使我们的模型能够实现二维张量并行,例如在4个 GPU 上,我们需要配置如下的并行设置。
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```python
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CONFIG = dict(parallel=dict(
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data=1,
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pipeline=1,
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tensor=dict(size=4, mode='2d'),
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))
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```
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然后 Colossal-AI 会自动对所有来自 `colossalai.nn` 的层应用2D张量并行。
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ColossalAI的最新版本还暂不支持2D张量并行,但2D张量并行的功能会在未来的版本被集成入`Shardformer`中。关于`Shardformer`的原理和用法细节请参考当前目录下的Shardformer文档。
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让我们定义一个由两层多层感知器 (MLP) 组成的模型,如下所示。
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```python
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import colossalai
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import colossalai.nn as col_nn
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import torch
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from colossalai.utils import print_rank_0
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对于老版本ColossalAI的用户,2D张量并行的用法请参考[ColossalAI-Examples - 2D Tensor Parallelism](https://github.com/hpcaitech/ColossalAI-Examples/blob/main/features/tensor_parallel/README.md)。
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class MLP(torch.nn.Module):
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def __init__(self, dim: int = 256):
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super().__init__()
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intermediate_dim = dim * 4
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self.dense_1 = col_nn.Linear(dim, intermediate_dim)
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print_rank_0(f'Weight of the first linear layer: {self.dense_1.weight.shape}')
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self.activation = torch.nn.GELU()
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self.dense_2 = col_nn.Linear(intermediate_dim, dim)
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print_rank_0(f'Weight of the second linear layer: {self.dense_2.weight.shape}')
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self.dropout = col_nn.Dropout(0.1)
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def forward(self, x):
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x = self.dense_1(x)
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print_rank_0(f'Output of the first linear layer: {x.shape}')
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x = self.activation(x)
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x = self.dense_2(x)
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print_rank_0(f'Output of the second linear layer: {x.shape}')
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x = self.dropout(x)
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return x
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```
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在4个 GPU 上启动 Colossal-AI 并建立模型。
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```python
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parser = colossalai.get_default_parser()
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colossalai.launch(config=CONFIG,
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rank=args.rank,
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world_size=args.world_size,
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local_rank=args.local_rank,
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host=args.host,
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port=args.port)
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m = MLP()
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```
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我们将会看到 MLP 模型中被划分的参数(如权重)的形状。
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```shell
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Weight of the first linear layer: torch.Size([128, 512])
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Weight of the second linear layer: torch.Size([512, 128])
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```
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第一个线性层的完整权重形状应该为 `[256, 1024]`. 经过2D并行划分后,它在每个 GPU 上变成了 `[128, 512]` 。
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同样地,第二层将权重 `[1024, 256]` 划分为 `[512, 128]`.
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我们可以用一些随机输入来运行这个模型。
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```python
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from colossalai.context import ParallelMode
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from colossalai.core import global_context as gpc
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from colossalai.utils import get_current_device
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x = torch.randn((16, 256), device=get_current_device())
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# partition input
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torch.distributed.broadcast(x, src=0)
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x = torch.chunk(x, 2, dim=0)[gpc.get_local_rank(ParallelMode.PARALLEL_2D_COL)]
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x = torch.chunk(x, 2, dim=-1)[gpc.get_local_rank(ParallelMode.PARALLEL_2D_ROW)]
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print_rank_0(f'Input: {x.shape}')
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x = m(x)
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```
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然后我们可以看到 activation 结果的形状。
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```shell
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Input: torch.Size([8, 128])
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Output of the first linear layer: torch.Size([8, 512])
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Output of the second linear layer: torch.Size([8, 128])
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```
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2D并行中的 activation 张量都是同时在行和列分割的。例如,第一个线性层的输出是 `[8, 512]`, 而第二层的输出为 `[8, 128]`。
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<!-- doc-test-command: echo -->
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