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Builds a graph operator that runs a replicated TPU computation.
tf.compat.v1.tpu.replicate(
computation, inputs=None, infeed_queue=None, device_assignment=None, name=None,
maximum_shapes=None, padding_spec=None, xla_options=None
)
Example for the basic usage that inputs has static shape:
def computation(x):
x = x + 1
return tf.math.reduce_mean(x)
x = tf.convert_to_tensor([1., 2., 3.])
y = tf.convert_to_tensor([4., 5., 6.])
tf.compat.v1.tpu.replicate(computation, inputs=[[x], [y]])
If the inputs has dynamic shapes and you would like to automatically
bucketize the inputs to avoid XLA recompilation. See the advanced example
below:
def computation(x):
x = x + 1
return tf.math.reduce_mean(x)
# Assume input tensors in two replicas `x` and `y` both have dynamic shape
# ([None, 2]).
tf.compat.v1.tpu.replicate(
computation,
inputs=[x, y],
maximum_shapes=[tf.TensorShape([None, None])],
padding_spec=tf.compat.v1.tpu.PaddingSpec.POWER_OF_TWO)
Args | |
|---|---|
computation
|
A Python function that builds the computation to replicate. |
inputs
|
A list of lists of input tensors or None (equivalent to
[[]]), indexed by [replica_num][input_num]. All replicas must
have the same number of inputs. Each input can be a nested structure
containing values that are convertible to tensors. Note that passing an
N-dimension list of compatible values will result in a N-dimension list of
scalar tensors rather than a single Rank-N tensors. If you need different
behavior, convert part of inputs to tensors with tf.convert_to_tensor.
|
infeed_queue
|
If not None, the InfeedQueue from which to append a tuple
of arguments as inputs to computation.
|
device_assignment
|
If not None, a DeviceAssignment describing the
mapping between logical cores in the computation with physical cores in
the TPU topology. Uses a default device assignment if None. The
DeviceAssignment may be omitted if each replica of the computation uses
only one core, and there is either only one replica, or the number of
replicas is equal to the number of cores in the TPU system.
|
name
|
(Deprecated) Does nothing. |
maximum_shapes
|
A nested structure of tf.TensorShape representing the shape
to which the respective component of each input element in each replica
should be padded. Any unknown dimensions (e.g.
tf.compat.v1.Dimension(None) in a tf.TensorShape or -1 in a tensor-like
object) will be padded to the maximum size of that dimension over all
replicas. The structure of maximum_shapes needs to be the same as
inputs[0].
|
padding_spec
|
An enum specified by tpu.PaddingSpec. This describes the
padding policy when the inputs to tpu.replicate is dynamic.
One usage is to enable automatic bucketizing on the inputs by setting the
value to tpu.PaddingSpec.POWER_OF_TWO, which can help to reduce the
recompilation in the XLA side.
|
xla_options
|
An instance of tpu.XLAOptions which indicates the options
passed to XLA compiler. Use None for default options.
|
Returns | |
|---|---|
A list of outputs, indexed by [replica_num] each output can be a nested
structure same as what computation() returns with a few exceptions.
Exceptions include: 1) None output: a NoOp would be returned which control-depends on computation. 2) Single value output: A tuple containing the value would be returned. 3) Operation-only outputs: a NoOp would be returned which control-depends on computation. |
Raises | |
|---|---|
ValueError
|
If all replicas do not have equal numbers of input tensors. |
ValueError
|
If the number of inputs per replica does not match
the number of formal parameters to computation.
|
ValueError
|
If the static inputs dimensions don't match with the values
given in maximum_shapes.
|
ValueError
|
If the structure of inputs per replica does not match
the structure of maximum_shapes.
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