lightning/pytorch_lightning/accelerators/tpu.py

74 lines
2.9 KiB
Python

from typing import Any, Callable, Optional, TYPE_CHECKING, Union
import torch
from torch.optim import Optimizer
from pytorch_lightning.accelerators.accelerator import Accelerator
from pytorch_lightning.plugins.precision import MixedPrecisionPlugin
from pytorch_lightning.plugins.training_type.single_tpu import SingleTPUPlugin
from pytorch_lightning.plugins.training_type.tpu_spawn import TPUSpawnPlugin
from pytorch_lightning.utilities import _XLA_AVAILABLE
from pytorch_lightning.utilities.exceptions import MisconfigurationException
if _XLA_AVAILABLE:
import torch_xla.core.xla_model as xm
from torch_xla._patched_functions import clip_grad_norm_
xla_clip_grad_norm_ = clip_grad_norm_
if TYPE_CHECKING:
from pytorch_lightning.core.lightning import LightningModule
from pytorch_lightning.trainer.trainer import Trainer
class TPUAccelerator(Accelerator):
def setup(self, trainer: 'Trainer', model: 'LightningModule') -> None:
"""
Raises:
MisconfigurationException:
If AMP is used with TPU, or if TPUs are not using a single TPU core or TPU spawn training.
"""
if isinstance(self.precision_plugin, MixedPrecisionPlugin):
raise MisconfigurationException(
"amp + tpu is not supported. "
"Only bfloats are supported on TPU. Consider using TPUHalfPrecisionPlugin"
)
if not isinstance(self.training_type_plugin, (SingleTPUPlugin, TPUSpawnPlugin)):
raise MisconfigurationException("TPUs only support a single tpu core or tpu spawn training.")
return super().setup(trainer, model)
def run_optimizer_step(
self, optimizer: Optimizer, optimizer_idx: int, lambda_closure: Callable, **kwargs: Any
) -> None:
xm.optimizer_step(optimizer, barrier=False, optimizer_args={'closure': lambda_closure, **kwargs})
def all_gather(self, tensor: torch.Tensor, group: Optional[Any] = None, sync_grads: bool = False) -> torch.Tensor:
"""
Function to gather a tensor from several distributed processes
Args:
tensor: tensor of shape (batch, ...)
group: not available with TPUs
sync_grads: not available with TPUs
Return:
A tensor of shape (world_size, batch, ...)
"""
# todo: Add support for backward with all_gather
if isinstance(self.training_type_plugin, TPUSpawnPlugin) and self.training_type_plugin.is_distributed:
return xm.all_gather(tensor).view(-1, *tensor.shape)
return tensor
def clip_gradients(self, optimizer: Optimizer, clip_val: Union[float, int], norm_type: float = 2.0):
model = self.lightning_module
parameters = model.parameters()
grad_clip_val = float(clip_val)
if grad_clip_val <= 0:
return
max_norm = grad_clip_val
xla_clip_grad_norm_(parameters, max_norm, norm_type)