Configuration reference

Note: this API is in preview and is subject to change.

A configuration file called genai_config.json is generated automatically if the model is generated with the model builder. If you provide your own model, you can copy the example below and modify it for your scenario.

Example file for phi-2

    "model": {
        "bos_token_id": 50256,
        "context_length": 2048,
        "decoder": {
            "session_options": {
                "log_id": "onnxruntime-genai",
                "provider_options": [
                        "cuda": {}
            "filename": "model.onnx",
            "head_size": 80,
            "hidden_size": 2560,
            "inputs": {
                "input_ids": "input_ids",
                "attention_mask": "attention_mask",
                "position_ids": "position_ids",
                "past_key_names": "past_key_values.%d.key",
                "past_value_names": "past_key_values.%d.value"
            "outputs": {
                "logits": "logits",
                "present_key_names": "present.%d.key",
                "present_value_names": "present.%d.value"
            "num_attention_heads": 32,
            "num_hidden_layers": 32,
            "num_key_value_heads": 32
        "eos_token_id": 50256,
        "pad_token_id": 50256,
        "type": "phi",
        "vocab_size": 51200
    "search": {
        "diversity_penalty": 0.0,
        "do_sample": false,
        "early_stopping": true,
        "length_penalty": 1.0,
        "max_length": 20,
        "min_length": 0,
        "no_repeat_ngram_size": 0,
        "num_beams": 1,
        "num_return_sequences": 1,
        "past_present_share_buffer": true,
        "repetition_penalty": 1.0,
        "temperature": 1.0,
        "top_k": 50,
        "top_p": 1.0


Model section

General model config

  • type: The type of model. Can be phi, llama or gpt.

  • vocab_size: The size of the vocabulary that the model processes ie the number of tokens in the vocabulary.

  • bos_token_id: The id of the beginning of sequence token.

  • eos_token_id: The id of the end of sequence token.

  • pad_token: The id of the padding token.

  • context_length: The maximum length of sequence that the model can process.

Session options

These are the options that are passed to ONNX Runtime, which runs the model on each token generation iteration.

  • provider_options: a prioritized list of execution targets on which to run the model. If running on CPU, this option is not present. A list of execution provider specific configurations can be specified inside the provider item.

  • log_id: a prefix to output when logging.

Then for each model in the pipeline there is one section, named by the model.

Decoder model config

  • filename: The name of the model file.

  • inputs: The names of each of the inputs. Sequences of model inputs can contain a wildcard representing the index in the sequence.

  • outputs: The names of each of the outputs.

  • num_attention_heads: The number of attention heads in the model.

  • head_size: The size of the attention heads.

  • hidden_size: The size of the hidden layers.

  • num_key_value_heads: The number of key value heads.

Generation search section

  • max_length: The maximum length that the model will generate.

  • min_length: The minimum length that the model will generate.

  • do_sample: Enables Top P / Top K generation. When set to true, generation uses the configured top_p and top_k values. When set to false, generation uses beam search or greedy search.

  • num_beams: The number of beams to apply when generating the output sequence using beam search. If num_beams=1, then generation is performed using greedy search. If num_beans > 1, then generation is performed using beam search.

  • early_stopping: Whether to stop the beam search when at least num_beams sentences are finished per batch or not. Defaults to false.

  • num_return_sequences: The number of sequences to generate. Returns the sequences with the highest scores in order.

  • top_k: Only includes tokens that do fall within the list of the K most probable tokens. Range is 1 to the vocabulary size.

  • top_p: Only includes the most probable tokens with probabilities that add up to P or higher. Defaults to 1, which includes all of the tokens. Range is 0 to 1, exclusive of 0.

  • temperature: The temperature value scales the probability of each token so that probable tokens become more likely while less probable ones become less likely. This value can have a range 0 < temperature ≤ 1. When temperature is equal to 1, it has no effect.

  • repetition_penalty: Discounts the scores of previously generated tokens if set to a value greater than 1. Defaults to 1.

  • length_penalty: Controls the length of the output generated. Value less than 1 encourages the generation to produce shorter sequences. Values greater than 1 encourages longer sequences. Defaults to 1.

  • diversity_penalty: Not supported.

  • no_repeat_ngram_size: Not supported.

  • past_present_share_buffer: If set to true, the past and present buffer are shared for efficiency.

Search combinations

  1. Beam search

    • num beams > 1
    • do_sample = False
  2. Greedy search

    • num_beams = 1
    • do_sample = False
  3. Top P / Top K

    • do_sample = True