tf.distribute.ReductionToOneDevice

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A CrossDeviceOps implementation that copies values to one device to reduce.

Inherits From: CrossDeviceOps

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Compat aliases for migration

See Migration guide for more details.

tf.compat.v1.distribute.ReductionToOneDevice

tf.distribute.ReductionToOneDevice(
    reduce_to_device=None, accumulation_fn=None
)

This implementation always copies values to one device to reduce them, then broadcast reduced values to the destinations. It doesn't support efficient batching.

Here is how you can use ReductionToOneDevice in tf.distribute.MirroredStrategy:

strategy = tf.distribute.MirroredStrategy(
  cross_device_ops=tf.distribute.ReductionToOneDevice())

Args
reduce_to_device	the intermediate device to reduce to. If None, reduce to the first device in destinations of the reduce method.
accumulation_fn	a function that does accumulation. If None, tf.math.add_n is used.

Methods

batch_reduce

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batch_reduce(
    reduce_op, value_destination_pairs, options=None
)

Reduce values to destinations in batches.

See tf.distribute.StrategyExtended.batch_reduce_to. This can only be called in the cross-replica context.

Args
reduce_op	a tf.distribute.ReduceOp specifying how values should be combined.
value_destination_pairs	a sequence of (value, destinations) pairs. See tf.distribute.CrossDeviceOps.reduce for descriptions.
options	a tf.distribute.experimental.CommunicationOptions. See tf.distribute.experimental.CommunicationOptions for details.

Returns
A list of tf.Tensor or tf.distribute.DistributedValues, one per pair in value_destination_pairs.

Raises
ValueError	if value_destination_pairs is not an iterable of tuples of tf.distribute.DistributedValues and destinations.

broadcast

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broadcast(
    tensor, destinations
)

Broadcast tensor to destinations.

This can only be called in the cross-replica context.

Args
tensor	a tf.Tensor like object. The value to broadcast.
destinations	a tf.distribute.DistributedValues, a tf.Variable, a tf.Tensor alike object, or a device string. It specifies the devices to broadcast to. Note that if it's a tf.Variable, the value is broadcasted to the devices of that variable, this method doesn't update the variable.

Returns
A tf.Tensor or tf.distribute.DistributedValues.

reduce

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reduce(
    reduce_op, per_replica_value, destinations, options=None
)

Reduce per_replica_value to destinations.

See tf.distribute.StrategyExtended.reduce_to. This can only be called in the cross-replica context.

Args
reduce_op	a tf.distribute.ReduceOp specifying how values should be combined.
per_replica_value	a tf.distribute.DistributedValues, or a tf.Tensor like object.
destinations	a tf.distribute.DistributedValues, a tf.Variable, a tf.Tensor alike object, or a device string. It specifies the devices to reduce to. To perform an all-reduce, pass the same to value and destinations. Note that if it's a tf.Variable, the value is reduced to the devices of that variable, and this method doesn't update the variable.
options	a tf.distribute.experimental.CommunicationOptions. See tf.distribute.experimental.CommunicationOptions for details.

Returns
A tf.Tensor or tf.distribute.DistributedValues.

Raises
ValueError	if per_replica_value can't be converted to a tf.distribute.DistributedValues or if destinations is not a string, tf.Variable or tf.distribute.DistributedValues.