Add custom head_dim support to Llama
Author: suhara
Pull request: yes

# What does this PR do?

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Llama assumes that `head_dim * num_heads == hidden_size` and does not accommodate any models with custom head_dim size. This PR relaxes the assumption and makes Llama use custom head_dim sizes. 

This PR has a dependency on the following PR:

- #32495 
    - `src/transformers/modeling_rope_utils.py` to use `config.head_dim` for RoPE.


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Comments:
cc @ArthurZucker 

Hi @ArthurZucker

The motivation is that some custom Llama-architecture based models with custom head_dim sizes cannot be loaded by `LlamaModel` due to this constraint. (Some context: https://github.com/NVIDIA/NeMo/pull/10078)

That said, I understand your concern on the regression issue. What would be your suggestion? If the existing Llama class is supposed to support official Llama models, creating a new class to cover custom Llama-based variant models would be an option?


Cool can you just run `make fixup` and `make fix-copies`

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_32502). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

@ArthurZucker It seems that you created another PR and fix the remaining issues for this. Thank you!

Hi @ArthurZucker 

I saw @Qubitium 's message in #32857. The newly created PR is missing the fix for `o_proj`.
I fixed the CI issues nd this PR should be ready to merge. Can you check?

Thanks!



Hi @ArthurZucker 

The CI passed. Can you merge this PR (or #32857 after fixing the issue)? Thanks!

#32857 has been merged. Close this PR.