[doc] add shardformer support matrix/update tensor parallel documents (#4728)

* add compatibility matrix for shardformer doc

* update tp doc
This commit is contained in:
Baizhou Zhang
2023-09-15 13:52:30 +08:00
committed by GitHub
parent 8c2dda7410
commit 50e5602c2d
10 changed files with 374 additions and 728 deletions

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@@ -2,14 +2,12 @@
作者: Zhengda Bian, Yongbin Li
> ⚠️ 此页面上的信息已经过时并将被废弃。请在[Shardformer](./shardformer.md)页面查阅更新。
**前置教程**
- [定义配置文件](../basics/define_your_config.md)
- [并行配置](../basics/configure_parallelization.md)
**示例代码**
- [ColossalAI-Examples 1D Tensor Parallelism](https://github.com/hpcaitech/ColossalAI-Examples/blob/main/features/tensor_parallel/README.md)
**示例代码**xw
- [Tensor Parallelism with Shardformer](https://github.com/hpcaitech/ColossalAI/tree/main/colossalai/shardformer/examples)
**相关论文**
- [Efficient Large-Scale Language Model Training on GPU Clusters Using Megatron-LM](https://deepakn94.github.io/assets/papers/megatron-sc21.pdf)
@@ -43,82 +41,10 @@ $$
| :-: | :-: | :-: | :-: | :-: |
| $O(1/P)$ | $O(1/P)$ | $O(1)$ | $O(2(P-1)/P)$ | $O(2(P-1))$ |
## 使用
为了使模型能够实现一维张量并行, 如在2个 GPU 上, 我们需要配置如下的并行设置
```python
CONFIG = dict(parallel=dict(
data=1,
pipeline=1,
tensor=dict(size=2, mode='1d'),
))
```
然后 Colossal-AI 会自动对所有来自 `colossalai.nn` 的层应用1D张量并行。
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。
```python
import colossalai
import colossalai.nn as col_nn
import torch
from colossalai.utils import print_rank_0
class MLP(torch.nn.Module):
def __init__(self, dim: int = 256):
super().__init__()
intermediate_dim = dim * 4
self.dense_1 = col_nn.Linear(dim, intermediate_dim)
print_rank_0(f'Weight of the first linear layer: {self.dense_1.weight.transpose(0, 1).shape}')
self.activation = torch.nn.GELU()
self.dense_2 = col_nn.Linear(intermediate_dim, dim)
print_rank_0(f'Weight of the second linear layer: {self.dense_2.weight.transpose(0, 1).shape}')
self.dropout = col_nn.Dropout(0.1)
def forward(self, x):
x = self.dense_1(x)
print_rank_0(f'Output of the first linear layer: {x.shape}')
x = self.activation(x)
x = self.dense_2(x)
print_rank_0(f'Output of the second linear layer: {x.shape}')
x = self.dropout(x)
return x
```
在2个 GPU 上启动 Colossal-AI 并建立模型。
```python
parser = colossalai.get_default_parser()
colossalai.launch(config=CONFIG,
rank=args.rank,
world_size=args.world_size,
local_rank=args.local_rank,
host=args.host,
port=args.port)
m = MLP()
```
我们将会看到 MLP 模型中被划分的参数(如权重)的形状。
```shell
Weight of the first linear layer: torch.Size([256, 512])
Weight of the second linear layer: torch.Size([512, 256])
```
第一个线性层的完整权重形状应该为 `[256, 1024]`. 经过列-并行分割,它变成了 `[256, 512]`
同样地,第二个行并行层将权重 `[1024, 256]` 划分为 `[512, 256]`
我们可以用一些随机输入来运行这个模型。
```python
from colossalai.utils import get_current_device
x = torch.randn((16, 256), device=get_current_device())
torch.distributed.broadcast(x, src=0) # synchronize input
x = m(x)
```
然后我们可以看到 activation 结果的形状。
```shell
Output of the first linear layer: torch.Size([16, 512])
Output of the second linear layer: torch.Size([16, 256])
```
第一个线性层的输出被划分成2块 (每个形状为 `[16, 512]`), 而第二层在整个 GPU 上的输出是相同的。
在ColossalAI最新的版本中1D张量并行由`Shardformer`功能实现
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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