On this page, you’ll learn how to configure and execute a pre-training run with some upstream validation. More specifically you’ll be pre-training a LLaMA3 8B model here as an example. By the end, you should be comfortable kicking off your own pre-training run for the model of your choice.

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Prerequisites

Please ensure that you have installed the Cerebras Model Zoo package by going through the installation guide. Make sure to have read through Trainer Overview and Trainer Configuration Overview which provide the basic overview of how to run Model Zoo models. In this document, you will be using the tools and configurations outlined in those pages.

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Configuring the Run

This page will cover the two main flows you can employ to perform pre-training. One using a YAML configuration file and a training script that is packaged in the Cerebras ModelZoo. The other using pure Python to run on your own. They will be presented side-by-side so that you can compare the two flows as you progress through this tutorial. If you aren’t interested in seeing the break down of the configuration, you can skip ahead to the Putting It All Together section to see the full configuration.

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Configure the Wafer-Scale Cluster

Let’s first figure out how much resources you’ll want to use for this pre-training job. In this example, let’s use a 16 node Wafer-Scale Cluster. To configure this, you can specify the number of Cerebras systems to use. 
trainer:
  init:
    backend:
      backend_type: CSX
      cluster_config:
        num_csx: 16
Notice how you can change cluster configuration parameters like num_csx to scale the run without making any changes to the model itself.

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Configure the Model

Here you will be pre-training the LLaMA3 model class that comes packaged inside of the Cerebras ModelZoo. The LLaMA3 model by default will compute the accuracy and perplexity metrics during upstream validation.
  • YAML: To configure the LLaMA3 8B model, you specify the following parameters to the model key.
  • Python: To configure the LLaMA3 8B model, you construct the model inside a lambda to take advantage of the Trainer’s efficient weight initialization feature. LLaMA3 is just a configuration of GPT2, hence why you are importing and initializing a Gpt2Model class. 
trainer:
  init:
    backend:  # CSX
      ...
    model:
      # Embedding
      vocab_size: 128256
      hidden_size: 4096
      position_embedding_type: "rotary"
      pos_scaling_factor: 1.0
      rope_theta: 500000.0
      rotary_dim: 128
      share_embedding_weights: false
      max_position_embeddings: 8192
      embedding_dropout_rate: 0.0
      embedding_layer_norm: false

      # Decoder
      num_hidden_layers: 32
      dropout_rate: 0.0
      layer_norm_epsilon: 1.0e-5
      norm_type: "rmsnorm"

      # Decoder - Attention
      num_heads: 32
      attention_type: "scaled_dot_product"
      attention_module: "multiquery_attention"
      attention_dropout_rate: 0.0
      use_projection_bias_in_attention: false
      use_ffn_bias_in_attention: false
      extra_attention_params:
          num_kv_groups: 8

      # Decoder - ffn
      filter_size: 14336
      nonlinearity: "swiglu"
      use_ffn_bias: false

      # Task-specific
      use_bias_in_output: false
      loss_scaling: "num_tokens"
      loss_weight: 1.0

      # Initializer
      initializer_range: 0.02

      # Cerebras parameters
      mixed_precision: True
      fp16_type: "cbfloat16"
    ...

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Configure the Optimizer

Here you will be using the AdamW optimizer to optimize our model during pre-training.
  • YAML: To configure the AdamW key. Note, you don’t specify a learning rate here as you will configure a learning rate scheduler, just below.
  • Python: Note, you specified a placeholder learning rate of 0.01 here as you will configure a learning rate scheduler, just below. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:
      AdamW:
        betas: [0.9, 0.95]
        correct_bias: True
        weight_decay: 0.1

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Configure a Learning Rate Scheduler

Here you will be using a CosineDecayLR learning rate scheduler. To configure the CosineDecayLR key. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:
    - CosineDecayLR:
        initial_learning_rate: 3.0e-5
        end_learning_rate: 3.0e-6
        total_iters: 528

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Configure Mixed Precision and Gradient Scaling

To get better performance, let’s use mixed precision in the run. More specifically, let’s configure the cluster to use cbfloat16 as the lower precision type (see CB16 Half-Precision for more details on the cbfloat16 data format). Since a lower precision is being used for activations, you’ll want to scale the gradients to prevent underflowing. Let’s use dynamic loss scaling for this run. In addition, to prevent gradients from exploding, let’s also clip the gradients based on its norm.
  • YAML: To configure the precision type and gradient scaling, you can specify the following parameters to the precision key.
  • Python: To configure the precision type and gradient scaling, you can construct a MixedPrecision object as follows. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:  # CosineDecayLR
      ...
    precision:
      fp16_type: cbfloat16
      loss_scaling_factor: dynamic
      max_gradient_norm: 1.0

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Configure the Training/Validation Loop

For this tutorial, let’s pre-train the model for 10k steps and run validation every 1k steps.
  • YAML: To configure the number of training and validation steps you can specify the following parameters to the loop key.
  • Python: To configure the number of training and validation steps, you can construct a TrainingLoop object as follows. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:  # CosineDecayLR
      ...
    precision:  # DLS
      ...
    loop:
      num_steps: 10000
      eval_frequency: 1000
      eval_steps: 1000

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Configure Checkpointing

In case you want to restart training from some point in the middle with different hyperparameters, let’s save a checkpoint every 1000 steps of training. This conveniently lines up nicely with the validation frequency you specified above so that you’ll know how well the model was performing at each checkpoint.
  • YAML: To configure how often checkpoints are taken, you specify the following parameters to the checkpoint key.
  • Python: To configure how often checkpoints are taken, you can construct a Checkpoint object as follows. 
trainer:
  init:
  backend:  \# CSX
  ...
  model:  \# llama
  ...
  optimizer:  \# AdamW
  ...
  schedulers:  \# CosineDecayLR
  ...
  precision:  \# DLS
  ...
  loop:
  ...
  checkpoint:
  steps:  1000

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Configure Callbacks

The following steps are completely optional. For this pre-training run, let’s keep track of the gradient norms to make sure that the model numerics are stable. In addition, let’s ensure that the loss values that the model is outputting are valid (i.e. not NaN or inf). Finally, since upstream validation is being run, let’s make sure that the validation metrics that are computed are being logged.
  • YAML: To configure these checks, you can specify the following callbacks to the callbacks key.
  • Python: To configure these checks, you can construct the following callbacks and pass them to the trainer. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:  # CosineDecayLR
      ...
    precision:  # DLS
      ...
    loop:
      ...
    checkpoint:
      ...
    callbacks:
    - ComputeNorm: {}
    - CheckLoss: {}
    - ModelEvalMetrics: {}

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Configure Loggers

To keep track of the progress of our run, let’s also employ the use of the progress logger as well as the TensorBoard logger.
  • YAML: To configure these loggers, you can specify the following to the loggers key.
  • Python: To configure these loggers, you can construct the following and pass them to the trainer. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:  # CosineDecayLR
      ...
    precision:  # DLS
      ...
    loop:
      ...
    checkpoint:
      ...
    callbacks:
      ...
    loggers:
    - ProgressLogger: {}
    - TensorBoardLogger: {}

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Reproducibility

In order to make the pre-training run reproducible, you must set the Trainer’s seed.
  • YAML: You can do this by specifying the seed key.
  • Python: You can do this by specifying the seed argument to the Trainer’s constructor as follows. 
trainer:
  init:
    backend:  # CSX
      ...
    model:  # llama
      ...
    optimizer:  # AdamW
      ...
    schedulers:  # CosineDecayLR
      ...
    precision:  # DLS
      ...
    loop:
      ...
    checkpoint:
      ...
    callbacks:
      ...
    loggers:
      ...
    seed: 2024
    ...
Setting different seeds across different runs of the same model may cause multiple compiles.

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Configuring the DataLoaders

Now that you’ve constructed the Trainer object, you’re almost ready to start the pre-training run. One of the only things left to do is to configure the training and validation dataloaders you’ll be using.
  • YAML: To configure the training and validation dataloaders, you can specify the following to the [train_dataloader](/model-zoo/trainer-configuration-overview key).
  • Python: To configure the training and validation dataloaders, you can construct DataLoader objects and pass them into the Trainer’s fit method as follows. 
trainer:
  init:
    ...
  fit:
    train_dataloader:
      data_processor: GptHDF5MapDataProcessor
      data_dir: "/data/llama_v3_dataset_vocab128256/train"
      batch_size: 80
      shuffle: False
      shuffle_seed: 1337
      num_workers: 8
      prefetch_factor: 10
      persistent_workers: True # Important to avoid seeding at each epoch
    val_dataloader:
    - data_processor: GptHDF5MapDataProcessor
      data_dir: "/data/llama_v3_dataset_vocab128256/val"
      batch_size: 80
      shuffle: False
      shuffle_seed: 1337
      num_workers: 8
      prefetch_factor: 10
      persistent_workers: True # Important to avoid seeding at each epoch
As can be seen, the specification of the training and validation dataloaders are very similar. The only difference is that you have the option of specifying multiple validation dataloaders to run validation over multiple datasets.
Please make sure to change the data_dir arguments to point to the actual directories containing the data.

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Putting It All Together

That is all there is to configuring the pre-training run! Let’s take a moment to step back and look at the full configuration that you’ve put together thus far. 
trainer:
  init:
    backend:
      backend_type: CSX
      cluster_config:
        num_csx: 16
    seed: 2024
    model:
      # Embedding
      vocab_size: 128256
      hidden_size: 4096
      position_embedding_type: "rotary"
      pos_scaling_factor: 1.0
      rope_theta: 500000.0
      rotary_dim: 128
      share_embedding_weights: false
      max_position_embeddings: 8192
      embedding_dropout_rate: 0.0
      embedding_layer_norm: false

      # Decoder
      num_hidden_layers: 32
      dropout_rate: 0.0
      layer_norm_epsilon: 1.0e-5
      norm_type: "rmsnorm"

      # Decoder - Attention
      num_heads: 32
      attention_type: "scaled_dot_product"
      attention_module: "multiquery_attention"
      attention_dropout_rate: 0.0
      use_projection_bias_in_attention: false
      use_ffn_bias_in_attention: false
      extra_attention_params:
          num_kv_groups: 8

      # Decoder - ffn
      filter_size: 14336
      nonlinearity: "swiglu"
      use_ffn_bias: false

      # Task-specific
      use_bias_in_output: false
      loss_scaling: "num_tokens"
      loss_weight: 1.0

      # Initializer
      initializer_range: 0.02

      # Cerebras parameters
      mixed_precision: True
      fp16_type: "cbfloat16"

    optimizer:
      AdamW:
        betas: [0.9, 0.95]
        correct_bias: True
        weight_decay: 0.1

    schedulers:
    - CosineDecayLR:
        initial_learning_rate: 3.0e-5
        end_learning_rate: 3.0e-6
        total_iters: 528

    precision:
      fp16_type: cbfloat16
      loss_scaling_factor: dynamic
      max_gradient_norm: 1.0

    loop:
      num_steps: 10000
      eval_frequency: 1000
      eval_steps: 1000

    checkpoint:
      steps: 1000

    callbacks:
    - ComputeNorm: {}
    - CheckLoss: {}
    - ModelEvalMetrics: {}

    loggers:
    - ProgressLogger: {}
    - TensorBoardLogger: {}
  fit:
    train_dataloader:
      data_processor: GptHDF5MapDataProcessor
      data_dir: "/data/llama_v3_dataset_vocab128256/train"
      batch_size: 80
      shuffle: False
      shuffle_seed: 1337
      num_workers: 8
      prefetch_factor: 10
      persistent_workers: True # Important to avoid seeding at each epoch
    val_dataloader:
    - data_processor: GptHDF5MapDataProcessor
      data_dir: "/data/llama_v3_dataset_vocab128256/val"
      batch_size: 80
      shuffle: False
      shuffle_seed: 1337
      num_workers: 8
      prefetch_factor: 10
      persistent_workers: True # Important to avoid seeding at each epoch

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Start Pre-Training

Now that you have a fully configured Trainer, all there is to do now is to kick off the run and start pre-training.
  • YAML: Let’s assume that the YAML configuration that you put together above is written to a file called ./pretrain_llama_8b.yaml. Then, to run pre-training using the training script that comes packaged as part of ModelZoo, you can run the following on the command line
  • Python: Let’s assume that the python code that you put together above is written to a file called ./pretrain_llama_8b.py. Then, to run pre-training, all there is to do is to execute that python script. 
python modelzoo/models/nlp/llama/run.py CSX \
    --mode train_and_eval \
    --params ./pretrain_llama_8b.yaml \

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Monitor the Run

Once compilation finishes and the Wafer-Scale Cluster is programmed for execution, you should start seeing progress logs that look like 
| Train Device=CSX, Step=1, Loss=1.39258, Rate=16.30 samples/sec, GlobalRate=16.30 samples/sec
| Train Device=CSX, Step=2, Loss=1.40430, Rate=20.40 samples/sec, GlobalRate=19.13 samples/sec
| Train Device=CSX, Step=3, Loss=1.38086, Rate=21.93 samples/sec, GlobalRate=20.25 samples/sec
| Train Device=CSX, Step=4, Loss=1.41211, Rate=22.45 samples/sec, GlobalRate=20.84 samples/sec
| Train Device=CSX, Step=5, Loss=1.35352, Rate=22.57 samples/sec, GlobalRate=21.17 samples/sec
| Train Device=CSX, Step=6, Loss=1.38477, Rate=22.54 samples/sec, GlobalRate=21.39 samples/sec
| Train Device=CSX, Step=7, Loss=1.39258, Rate=22.52 samples/sec, GlobalRate=21.54 samples/sec
| Train Device=CSX, Step=8, Loss=1.37695, Rate=22.44 samples/sec, GlobalRate=21.64 samples/sec
| Train Device=CSX, Step=9, Loss=1.40234, Rate=22.33 samples/sec, GlobalRate=21.71 samples/sec
| Train Device=CSX, Step=10, Loss=1.38281, Rate=22.38 samples/sec, GlobalRate=21.78 samples/sec
| Train Device=CSX, Step=11, Loss=1.39453, Rate=21.32 samples/sec, GlobalRate=21.67 samples/sec
| Train Device=CSX, Step=12, Loss=1.39844, Rate=21.72 samples/sec, GlobalRate=21.69 samples/sec
| Train Device=CSX, Step=13, Loss=1.38672, Rate=21.88 samples/sec, GlobalRate=21.71 samples/sec
| Train Device=CSX, Step=14, Loss=1.34961, Rate=21.91 samples/sec, GlobalRate=21.73 samples/sec
| Train Device=CSX, Step=15, Loss=1.33203, Rate=21.88 samples/sec, GlobalRate=21.74 samples/sec
| Train Device=CSX, Step=16, Loss=1.33008, Rate=21.91 samples/sec, GlobalRate=21.75 samples/sec
| Train Device=CSX, Step=17, Loss=1.33984, Rate=21.88 samples/sec, GlobalRate=21.76 samples/sec
| Train Device=CSX, Step=18, Loss=1.31250, Rate=21.88 samples/sec, GlobalRate=21.76 samples/sec
| Train Device=CSX, Step=19, Loss=1.36133, Rate=21.91 samples/sec, GlobalRate=21.77 samples/sec
| Train Device=CSX, Step=20, Loss=1.30664, Rate=23.15 samples/sec, GlobalRate=21.87 samples/sec
| Train Device=CSX, Step=21, Loss=1.30078, Rate=22.52 samples/sec, GlobalRate=21.88 samples/sec
| Train Device=CSX, Step=22, Loss=1.31250, Rate=22.23 samples/sec, GlobalRate=21.89 samples/sec
| Train Device=CSX, Step=23, Loss=1.30664, Rate=21.10 samples/sec, GlobalRate=21.82 samples/sec
| Train Device=CSX, Step=24, Loss=1.30469, Rate=22.73 samples/sec, GlobalRate=21.90 samples/sec
| Train Device=CSX, Step=25, Loss=1.28906, Rate=21.42 samples/sec, GlobalRate=21.84 samples/sec
...
| Eval Device=CSX, GlobalStep=1000, Batch=1, Loss=1.21875, Rate=21.47 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=2, Loss=1.24219, Rate=22.65 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=3, Loss=1.26562, Rate=22.06 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=4, Loss=1.25195, Rate=21.90 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=5, Loss=1.27539, Rate=21.80 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=6, Loss=1.23047, Rate=21.79 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=7, Loss=1.22852, Rate=20.72 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=8, Loss=1.27734, Rate=21.24 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=9, Loss=1.23633, Rate=22.57 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=10, Loss=1.27930, Rate=22.10 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=11, Loss=1.23438, Rate=20.86 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=12, Loss=1.24609, Rate=21.31 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=13, Loss=1.23633, Rate=21.47 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=14, Loss=1.23633, Rate=21.48 samples/sec, GlobalRates=21.66 samples/sec
| Eval Device=CSX, GlobalStep=1000, Batch=15, Loss=1.21680, Rate=22.66 samples/sec, GlobalRates=21.66 samples/sec
...
The performance numbers that you get will vary depending on how many Cerebras systems you are using and which generation systems you are using.
If you open up the TensorBoard you can more closely monitor the run be observing the trends in the graphs of the various logged metrics. 
tensorboard --bind_all --logdir="./model_dir"
As can be seen above, the screenshots were taken at around step 5800. At this point you can observe that so far, the run seems to progressing well. The losses appear to be trending downwards and the model wise gradient norms don’t appear overly abnormal.

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Porting the Model to Hugging Face

Once the pre-training run has finished, you can port the model and checkpoint to Hugging Face. To learn more about how to do this, see Port a trained and fine-tuned model to Hugging Face.

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Conclusion

With that, you have completed your first pre-training run with validation on the Cerebras Wafer-Scale Cluster using the ModelZoo Trainer! By now, you should understand how to write your own Trainer configuration and how to kick off a training job on the Cerebras Wafer-Scale Cluster. You can now take this knowledge and pre-train your very own model.