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Comment by arugulum | Hacker News Reader

> This technique is being used to reproduce[0] the Alpaca results from Stanford[1]

Reproduced is a strong statement, without any rigorous justification other than a few cherry-picked examples. Alpaca-LoRA is simply LLaMA with LoRA-tuning on the Alpaca data. There are no metrics, no measurements, no evaluations to show that the Alpaca-LoRA performs similarly to Alpaca, when it is well-known in the field that parameter-efficient fine-tuning always pays a cost in terms of performance relative to full fine-tuning (which is what Alpaca does).

(This has been a huge nit for me because of the recent flood of Alpaca-replications, or even claims that Alpaca comparable to ChatGPT, rushing to market themselves, but with nothing to justify their claims.)

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>when it is well-known in the field that parameter-efficient fine-tuning always pays a cost in terms of performance relative to full fine-tuning

The LoRA paper clearly states the performance of the method "LoRA performs on-par or better than fine-tuning in model quality on RoBERTa, DeBERTa, GPT-2, and GPT-3, despite having fewer trainable parameters, a higher training throughput, and, unlike adapters, no additional inference latency. ": https://arxiv.org/abs/2106.09685

I don't want to get into the weeds of the subtleties of evaluation, hyperparameter-tuning and model comparisons, but let's just say that subsequent studies have shown that LoRA (consistent with most parameter-efficient tuning methods) underperform full fine-tuning: https://arxiv.org/abs/2203.06904

As simple way to think about it is this: if LoRA really gives full fine-tuning performance, why would anyone ever fully fine-tune a model?

>why would anyone ever fully fine-tune a model?

You're asking it as if it were a rhetorical question, but I think it carries more weight than many people seem to believe.

To balance my view a little, it is definitely a valid question to ask "how far can we get with parameter-efficient tuning", and I firmly believe that as models get larger, the answer is "very, very far".

That said, I also dislike it when it is carelessly claimed that parameter-efficient tuning is as good as full fine-tuning, without qualifications or nuance.

I agree that it does carry weight.

It is not apparent to me that fine tuning should be better, especially since the LoRA method seems like it could be robust against catastrophic forgetting.

I 100% agree with you, but I (we) need more evidence.

I agree - my comment originally had a parenthetical about this fact, but I thought it was probably confusing to people who just wanted to understand what this was about. Perhaps I shouldn't have edited it out.

It also bothers me that a lot of LoRA claims read like "You won't believe how little it costs to train these models!", when of course 99%+ of the complexity and cost is in the LLaMA (or whatever) model that underpins it. Folks are talking about it in a loose way that implies some kind of miraculous overall training cost breakthrough.

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