# Copyright 2022 Cerebras Systems.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
This module contains the BackendCallback class which is used to set the backend
for the trainer.
"""
import cerebras.pytorch as cstorch
from cerebras.modelzoo.trainer.callbacks import Callback
[docs]class BackendCallback(Callback):
"""Callback to set the backend for the trainer."""
def __init__(self, backend, device):
"""
Args:
backend (cstorch.Backend or None): The backend object to be used for the trainer.
If None, the device argument must be provided.
If both are provided, an error is raised.
device (str or None): The device type to be used for the trainer. If None, the
backend argument must be provided.
"""
self.backend = backend
self.device = device
def setup(self, trainer):
if self.backend is None:
if isinstance(self.device, str):
accepted_device_types = {"CSX", "CPU", "GPU"}
if self.device.upper() not in accepted_device_types:
raise ValueError(
f"Invalid device type: {self.device}. "
f"Expected one of {accepted_device_types}."
)
backend = cstorch.current_backend(
raise_exception=False, raise_warning=False
)
if backend is None:
trainer.backend = cstorch.backend(
self.device, trainer.artifact_dir
)
else:
if backend.backend_type.name.lower() != self.device.lower():
raise ValueError(
"Cannot instantiate multiple trainers with different device types"
)
trainer.backend = backend
trainer.backend.artifact_dir = trainer.artifact_dir
else:
raise RuntimeError(
f"Trainer expected a backend object or a device string"
)
else:
from cerebras.pytorch.backend import Backend
if not isinstance(self.backend, Backend):
raise TypeError(
f"Expected backend to be a cstorch.Backend object. "
f"Got: {type(self.backend)}"
)
elif self.device is not None:
raise ValueError(
f"backend and device are mutually exclusive arguments of Trainer. "
"Please only provide one or the other"
)
trainer.backend = self.backend
# Set the backend's artifact directory to be the same as the
# trainer's artifact directory
trainer.backend.artifact_dir = trainer.artifact_dir