message: Enable TPU embedding feedback directed partitioning in Cloud by specifying a
  directory to save/restore profile data in the TPU embedding configuration.
diff: @@ -87,6 +87,22 @@ message TPUEmbeddingConfiguration {
  // problem.
  bool pipeline_execution_with_tensor_core = 7;
  + // Directory where embedding lookup statistics are stored. Lookup statistics
  + // summarize information about the inputs to the embedding lookup
  + // operation, in particular, the average number of embedding IDs per example
  + // and how well the embedding IDs are load balanced across the system. These
  + // statistics are used during TPU initialization for embedding table
  + // partitioning. Collection of lookup statistics is done at runtime by
  + // profiling the embedding inputs: only 3% of input samples are profiled to
  + // minimize host CPU overhead. Once a suitable number of samples are
  + // profiled, the lookup statistics are saved to table-specific files in the
  + // profile data directory generally at the end of a TPU training loop. The
  + // filename corresponding to each table is obtained by hashing table specific
  + // parameters (e.g., table name, number of features, sharding strategy, etc).
  + // The same profile data directory can be shared amongst several models to
  + // reuse embedding lookup statistics.
  + string profile_data_directory = 9;
  +
  // Extended output layout information; deprecated and now ignored.
  TPUEmbeddingOutputLayout output_layout = 8 [deprecated = true];
  }
  