finetuning

Finetuning Llama

This folder contains instructions to fine-tune Meta Llama 3 on a

• single-GPU setup
• multi-GPU setup

using the canonical finetuning script in the llama-recipes package.

If you are new to fine-tuning techniques, check out an overview:

Tip

If you want to try finetuning Meta Llama 3 with Huggingface's trainer, here is a Jupyter notebook with an example

How to configure finetuning settings?

Tip

All the setting defined in config files can be passed as args through CLI when running the script, there is no need to change from config files directly.

• Training config file is the main config file that helps to specify the settings for our run and can be found in configs folder

It lets us specify the training settings for everything from model_name to dataset_name, batch_size and so on. Below is the list of supported settings:

    model_name: str="PATH/to/Model"
    tokenizer_name: str=None
    enable_fsdp: bool=False
    low_cpu_fsdp: bool=False
    run_validation: bool=True
    batch_size_training: int=4
    batching_strategy: str="packing" #alternative: padding
    context_length: int=4096
    gradient_accumulation_steps: int=1
    gradient_clipping: bool = False
    gradient_clipping_threshold: float = 1.0
    num_epochs: int=3
    max_train_step: int=0
    max_eval_step: int=0
    num_workers_dataloader: int=1
    lr: float=1e-4
    weight_decay: float=0.0
    gamma: float= 0.85
    seed: int=42
    use_fp16: bool=False
    mixed_precision: bool=True
    val_batch_size: int=1
    dataset = "samsum_dataset"
    peft_method: str = "lora" # None,llama_adapter, prefix
    use_peft: bool=False
    output_dir: str = "PATH/to/save/PEFT/model"
    freeze_layers: bool = False
    num_freeze_layers: int = 1
    quantization: bool = False
    one_gpu: bool = False
    save_model: bool = True
    dist_checkpoint_root_folder: str="PATH/to/save/FSDP/model" # will be used if using FSDP
    dist_checkpoint_folder: str="fine-tuned" # will be used if using FSDP
    save_optimizer: bool=False # will be used if using FSDP
    use_fast_kernels: bool = False # Enable using SDPA from PyTroch Accelerated Transformers, make use Flash Attention and Xformer memory-efficient kernels
    use_wandb: bool = False # Enable wandb for experient tracking
    save_metrics: bool = False # saves training metrics to a json file for later plotting
    flop_counter: bool = False # Enable flop counter to measure model throughput, can not be used with pytorch profiler at the same time.
    flop_counter_start: int = 3 # The step to start profiling, default is 3, which means after 3 steps of warmup stage, the profiler will start to count flops.
    use_profiler: bool = False # Enable pytorch profiler, can not be used with flop counter at the same time.
    profiler_dir: str = "PATH/to/save/profiler/results" # will be used if using profiler

• Datasets config file provides the available options for datasets.

• peft config file provides the supported PEFT methods and respective settings that can be modified. We currently support LoRA and Llama-Adapter. Please note that LoRA is the only technique which is supported in combination with FSDP.

• FSDP config file provides FSDP settings such as:

  • mixed_precision boolean flag to specify using mixed precision, defatults to true.

  • use_fp16 boolean flag to specify using FP16 for mixed precision, defatults to False. We recommond not setting this flag, and only set mixed_precision that will use BF16, this will help with speed and memory savings while avoiding challenges of scaler accuracies with FP16.

  • sharding_strategy this specifies the sharding strategy for FSDP, it can be:

    • FULL_SHARD that shards model parameters, gradients and optimizer states, results in the most memory savings.

    • SHARD_GRAD_OP that shards gradinets and optimizer states and keeps the parameters after the first all_gather. This reduces communication overhead specially if you are using slower networks more specifically beneficial on multi-node cases. This comes with the trade off of higher memory consumption.

    • NO_SHARD this is equivalent to DDP, does not shard model parameters, gradinets or optimizer states. It keeps the full parameter after the first all_gather.

    • HYBRID_SHARD available on PyTorch Nightlies. It does FSDP within a node and DDP between nodes. It's for multi-node cases and helpful for slower networks, given your model will fit into one node.

• checkpoint_type specifies the state dict checkpoint type for saving the model. FULL_STATE_DICT streams state_dict of each model shard from a rank to CPU and assembels the full state_dict on CPU. SHARDED_STATE_DICT saves one checkpoint per rank, and enables the re-loading the model in a different world size.

• fsdp_activation_checkpointing enables activation checkpoining for FSDP, this saves significant amount of memory with the trade off of recomputing itermediate activations during the backward pass. The saved memory can be re-invested in higher batch sizes to increase the throughput. We recommond you use this option.

• pure_bf16 it moves the model to BFloat16 and if optimizer is set to anyprecision then optimizer states will be kept in BFloat16 as well. You can use this option if necessary.

Weights & Biases Experiment Tracking

You can enable W&B experiment tracking by using use_wandb flag as below. You can change the project name, entity and other wandb.init arguments in wandb_config.

python -m llama_recipes.finetuning --use_peft --peft_method lora --quantization --model_name /path_of_model_folder/8B --output_dir Path/to/save/PEFT/model --use_wandb

You'll be able to access a dedicated project or run link on wandb.ai and see your dashboard like the one below.

FLOPS Counting and Pytorch Profiling

To help with benchmarking effort, we are adding the support for counting the FLOPS during the fine-tuning process. You can achieve this by setting --flop_counter when launching your single/multi GPU fine-tuning. Use --flop_counter_start to choose which step to count the FLOPS. It is recommended to allow a warm-up stage before using the FLOPS counter.

Similarly, you can set --use_profiler flag and pass a profiling output path using --profiler_dir to capture the profile traces of your model using PyTorch profiler. To get accurate profiling result, the pytorch profiler requires a warm-up stage and the current config is wait=1, warmup=2, active=3, thus the profiler will start the profiling after step 3 and will record the next 3 steps. Therefore, in order to use pytorch profiler, the --max-train-step has been greater than 6. The pytorch profiler would be helpful for debugging purposes. However, the --flop_counter and --use_profiler can not be used in the same time to ensure the measurement accuracy.