This document is relevant for: Inf1, Inf2, Trn1, Trn2, Trn3

NCC_EARG001#

Error message: This error occurs when you attempt to use a Logical Neuron Core (LNC) configuration that is not supported by the target Neuron architecture.

For example, a trn1 instance running the following code will run into this error:

traced_model = torch_neuronx.trace(
   model,
   input,
   compiler_args=['--lnc', '2']  # ERROR: lnc=2 not supported on trn1
)

On trn1, only lnc=1 is supported.

Physical Neuron Core:

  • Actual hardware compute unit on the chip

  • Has dedicated compute resources, memory, etc.

Logical Neuron Core:

  • Software abstraction grouping multiple physical cores

  • Controlled via the NEURON_LOGICAL_NC_CONFIG environment variable or the –lnc flag (when using neuronx-cc directly)

For more information: https://awsdocs-neuron.readthedocs-hosted.com/en/latest/neuron-runtime/explore/device-memory.html#logical-neuron-cores

This document is relevant for: Inf1, Inf2, Trn1, Trn2, Trn3