|View source on GitHub|
computation for parallel execution.
tf.tpu.shard( computation, inputs=None, num_shards=1, input_shard_axes=None, outputs_from_all_shards=True, output_shard_axes=None, infeed_queue=None, device_assignment=None, name=None )
inputs must be a list of Tensors or None (equivalent to an empty list), each
of which has a corresponding split axis (from
input_shard_axes). Each input
is split into
num_shards pieces along the corresponding axis, and
computation is applied to each shard in parallel.
Tensors are broadcast to all shards if they are lexically captured by
x = tf.constant(7) def computation(): return x + 3 ... = shard(computation, ...)
TODO(phawkins): consider adding support for broadcasting Tensors passed as inputs.
outputs_from_all_shards is true, the outputs from all shards of
computation are concatenated back together along their
Otherwise, each output is taken from an arbitrary shard.
Inputs and outputs of the computation must be at least rank-1 Tensors.
computation: A Python function that builds a computation to apply to each shard of the input.
inputs: A list of input tensors or None (equivalent to an empty list). Each input tensor has a corresponding shard axes, given by
input_shard_axes, which must have size divisible by
num_shards: The number of shards.
input_shard_axes: A list of dimensions along which to shard
Nonemeans "shard all inputs along dimension 0". If not
None, there must be one dimension per input.
outputs_from_all_shards: Boolean or list of boolean. For each output, if
True, outputs from all shards are concatenated along the corresponding
output_shard_axesentry. Otherwise, each output is taken from an arbitrary shard. If the argument is a boolean, the argument's value is used for each output.
output_shard_axes: A list of dimensions along which to concatenate the outputs of
Nonemeans "concatenate all outputs along dimension 0". If not
None, there must be one dimension per output. Ignored if
infeed_queue: If not
InfeedQueueto use to augment the inputs of
device_assignment: If not
DeviceAssignmentdescribing the mapping between logical cores in the computation with physical cores in the TPU topology. Uses a default device assignment if
DeviceAssignmentmay be omitted if each shard of the computation uses only one core, and there is either only one shard, or the number of shards is equal to the number of cores in the TPU system.
name: (Deprecated) Does nothing.
A list of output tensors.
ValueError: If num_shards <= 0
ValueError: If len(input_shard_axes) != len(inputs)
ValueError: If len(output_shard_axes) != len(outputs from