tf.tpu.experimental.DeviceAssignment

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Mapping from logical cores in a computation to the physical TPU topology.

tf.tpu.experimental.DeviceAssignment(
    topology, core_assignment
)

Prefer to use the DeviceAssignment.build() helper to construct a DeviceAssignment; it is easier if less flexible than constructing a DeviceAssignment directly.

Args:

• topology: A Topology object that describes the physical TPU topology.
• core_assignment: A logical to physical core mapping, represented as a rank 3 numpy array. See the description of the core_assignment property for more details.

Attributes:

• core_assignment: The logical to physical core mapping.

• num_cores_per_replica: The number of cores per replica.

• num_replicas: The number of replicas of the computation.

• topology: A Topology that describes the TPU topology.

Raises:

• ValueError: If topology is not Topology object.
• ValueError: If core_assignment is not a rank 3 numpy array.

Methods

build

View source

@staticmethod
build(
    topology, computation_shape=None, computation_stride=None, num_replicas=1
)

coordinates

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coordinates(
    replica, logical_core
)

Returns the physical topology coordinates of a logical core.

host_device

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host_device(
    replica=0, logical_core=0, job=None
)

Returns the CPU device attached to a logical core.

lookup_replicas

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lookup_replicas(
    task_id, logical_core
)

Lookup replica ids by task number and logical core.

Args:

• task_id: TensorFlow task number.
• logical_core: An integer, identifying a logical core.

Returns:

A sorted list of the replicas that are attached to that task and logical_core.

Raises:

• ValueError: If no replica exists in the task which contains the logical core.

tpu_device

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tpu_device(
    replica=0, logical_core=0, job=None
)

Returns the name of the TPU device assigned to a logical core.

tpu_ordinal

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tpu_ordinal(
    replica=0, logical_core=0
)

Returns the ordinal of the TPU device assigned to a logical core.