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Shards computation
for parallel execution.
tf.compat.v1.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, xla_options=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
computation
. e.g.,
x = tf.constant(7) def computation(): return x + 3 ... = shard(computation, ...)
as inputs.
If outputs_from_all_shards
is true, the outputs from all shards of
computation
are concatenated back together along their output_shard_axes
.
Otherwise, each output is taken from an arbitrary shard.
Inputs and outputs of the computation must be at least rank-1 Tensors.
Args | |
---|---|
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 .
|
num_shards
|
The number of shards. |
input_shard_axes
|
A list of dimensions along which to shard inputs , or
None . None means "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_axes entry. 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 computation , or None . None means "concatenate all outputs
along dimension 0". If not None , there must be one dimension per output.
Ignored if outputs_from_all_shards is False.
|
infeed_queue
|
If not None , the InfeedQueue to use to augment the inputs
of 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 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. |
xla_options
|
An instance of tpu.XLAOptions which indicates the options
passed to XLA compiler. Use None for default options.
|
Returns | |
---|---|
A list of output tensors. |
Raises | |
---|---|
ValueError
|
If num_shards <= 0 |
ValueError
|
If len(input_shard_axes) != len(inputs) |
ValueError
|
If len(output_shard_axes) != len(outputs from computation )
|