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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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@@ -60,83 +60,9 @@ Given $P=q\times q$ processors, we present the theoretical computation and memor
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## Usage
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To enable 2D tensor parallelism for our model, e.g. on 4 GPUs, we need to configure the parallelism setting as below.
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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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Then Colossal-AI will automatically apply 2D parallelism to all the layers from `colossalai.nn`.
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Currently the newest version of ColossalAI doesn't support 2D tensor parallelism, but this feature will be integrated into `Shardformer` in future releases.
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For more details about ideas and usages of `Shardformer`, please refer to [Shardformer Doc](./shardformer.md).
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Let's define a model that consists of a two-layer multi-layer perceptron (MLP) as below.
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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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For users of older version of ColossalAI, please refer to [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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Launch Colossal-AI on 4 GPUs and build the model
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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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We will see the shapes of partitioned parameters(e.g. weights) in the MLP model.
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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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The complete weight of the first linear layer is supposed to have the shape `[256, 1024]`. After the partitioning of 2D parallelism, it becomes `[128, 512]` on each GPU.
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Similarly, the second layer partitions the weight `[1024, 256]` into `[512, 128]`.
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We can run the model with some random inputs.
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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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Then we can see the shapes of activation results.
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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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The activation tensors in 2D parallelism are all split in both row and column.
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E.g. the output of the first linear layer has the shape `[8, 512]`, while the second layer has the output of `[8, 128]`.
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<!-- doc-test-command: echo -->
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