TPU training with PyTorch Lightning¶
Author: PL team
License: CC BY-SA
Generated: 2021-07-17T09:05:13.252067
In this notebook, we’ll train a model on TPUs. Updating one Trainer flag is all you need for that. The most up to documentation related to TPU training can be found here.
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Setup¶
This notebook requires some packages besides pytorch-lightning.
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! pip install --quiet "torchvision" "torchmetrics>=0.3" "pytorch-lightning>=1.3" "torch>=1.6, <1.9"
Install Colab TPU compatible PyTorch/TPU wheels and dependencies¶
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! pip install cloud-tpu-client==0.10 https://storage.googleapis.com/tpu-pytorch/wheels/torch_xla-1.8-cp37-cp37m-linux_x86_64.whl
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import torch
import torch.nn.functional as F
from pytorch_lightning import LightningDataModule, LightningModule, Trainer
from torch import nn
from torch.utils.data import DataLoader, random_split
from torchmetrics.functional import accuracy
from torchvision import transforms
# Note - you must have torchvision installed for this example
from torchvision.datasets import MNIST
BATCH_SIZE = 1024
Defining The MNISTDataModule¶
Below we define MNISTDataModule. You can learn more about datamodules in docs.
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class MNISTDataModule(LightningDataModule):
def __init__(self, data_dir: str = './'):
super().__init__()
self.data_dir = data_dir
self.transform = transforms.Compose([
transforms.ToTensor(), transforms.Normalize((0.1307, ), (0.3081, ))
])
# self.dims is returned when you call dm.size()
# Setting default dims here because we know them.
# Could optionally be assigned dynamically in dm.setup()
self.dims = (1, 28, 28)
self.num_classes = 10
def prepare_data(self):
# download
MNIST(self.data_dir, train=True, download=True)
MNIST(self.data_dir, train=False, download=True)
def setup(self, stage=None):
# Assign train/val datasets for use in dataloaders
if stage == 'fit' or stage is None:
mnist_full = MNIST(self.data_dir, train=True, transform=self.transform)
self.mnist_train, self.mnist_val = random_split(mnist_full, [55000, 5000])
# Assign test dataset for use in dataloader(s)
if stage == 'test' or stage is None:
self.mnist_test = MNIST(self.data_dir, train=False, transform=self.transform)
def train_dataloader(self):
return DataLoader(self.mnist_train, batch_size=BATCH_SIZE)
def val_dataloader(self):
return DataLoader(self.mnist_val, batch_size=BATCH_SIZE)
def test_dataloader(self):
return DataLoader(self.mnist_test, batch_size=BATCH_SIZE)
Defining the LitModel¶
Below, we define the model LitMNIST.
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class LitModel(LightningModule):
def __init__(self, channels, width, height, num_classes, hidden_size=64, learning_rate=2e-4):
super().__init__()
self.save_hyperparameters()
self.model = nn.Sequential(
nn.Flatten(), nn.Linear(channels * width * height, hidden_size), nn.ReLU(), nn.Dropout(0.1),
nn.Linear(hidden_size, hidden_size), nn.ReLU(), nn.Dropout(0.1),
nn.Linear(hidden_size, num_classes)
)
def forward(self, x):
x = self.model(x)
return F.log_softmax(x, dim=1)
def training_step(self, batch, batch_idx):
x, y = batch
logits = self(x)
loss = F.nll_loss(logits, y)
self.log('train_loss', loss)
return loss
def validation_step(self, batch, batch_idx):
x, y = batch
logits = self(x)
loss = F.nll_loss(logits, y)
preds = torch.argmax(logits, dim=1)
acc = accuracy(preds, y)
self.log('val_loss', loss, prog_bar=True)
self.log('val_acc', acc, prog_bar=True)
return loss
def configure_optimizers(self):
optimizer = torch.optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
return optimizer
TPU Training¶
Lightning supports training on a single TPU core or 8 TPU cores.
The Trainer parameters tpu_cores defines how many TPU cores to train on (1 or 8) / Single TPU core to train on [1].
For Single TPU training, Just pass the TPU core ID [1-8] in a list. Setting tpu_cores=[5] will train on TPU core ID 5.
Train on TPU core ID 5 with tpu_cores=[5].
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# Init DataModule
dm = MNISTDataModule()
# Init model from datamodule's attributes
model = LitModel(*dm.size(), dm.num_classes)
# Init trainer
trainer = Trainer(max_epochs=3, progress_bar_refresh_rate=20, tpu_cores=[5])
# Train
trainer.fit(model, dm)
Train on single TPU core with tpu_cores=1.
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# Init DataModule
dm = MNISTDataModule()
# Init model from datamodule's attributes
model = LitModel(*dm.size(), dm.num_classes)
# Init trainer
trainer = Trainer(max_epochs=3, progress_bar_refresh_rate=20, tpu_cores=1)
# Train
trainer.fit(model, dm)
Train on 8 TPU cores with tpu_cores=8. You might have to restart the notebook to run it on 8 TPU cores after training on single TPU core.
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# Init DataModule
dm = MNISTDataModule()
# Init model from datamodule's attributes
model = LitModel(*dm.size(), dm.num_classes)
# Init trainer
trainer = Trainer(max_epochs=3, progress_bar_refresh_rate=20, tpu_cores=8)
# Train
trainer.fit(model, dm)
Congratulations - Time to Join the Community!¶
Congratulations on completing this notebook tutorial! If you enjoyed this and would like to join the Lightning movement, you can do so in the following ways!
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You can also contribute your own notebooks with useful examples !
Great thanks from the entire Pytorch Lightning Team for your interest !¶
