fsdp_utils.py

# Copyright (c) Meta Platforms, Inc. and affiliates.
# This software may be used and distributed according to the terms of the Llama 2 Community License Agreement.

def fsdp_auto_wrap_policy(model, transformer_layer_name):
    import functools

    from torch.distributed.fsdp.wrap import _or_policy, lambda_auto_wrap_policy, transformer_auto_wrap_policy

    from peft.tuners import PrefixEncoder, PromptEmbedding, PromptEncoder

    def lambda_policy_fn(module):
        if (
            len(list(module.named_children())) == 0
            and getattr(module, "weight", None) is not None
            and module.weight.requires_grad
        ):
            return True
        return False

    lambda_policy = functools.partial(lambda_auto_wrap_policy, lambda_fn=lambda_policy_fn)
    transformer_wrap_policy = functools.partial(
        transformer_auto_wrap_policy,
        transformer_layer_cls=(
            PrefixEncoder,
            PromptEncoder,
            PromptEmbedding,
            transformer_layer_name,
            # FullyShardedDataParallelPlugin.get_module_class_from_name(
            #     model, transformer_layer_name
            # ),
        ),
    )

    auto_wrap_policy = functools.partial(_or_policy, policies=[lambda_policy, transformer_wrap_policy])
    return auto_wrap_policy