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@cajeonrh cajeonrh commented Oct 2, 2025

SUMMARY:
Created a FAQ page under the "Getting Started" section

TEST PLAN:

  • Created a new page called FAQ under "Getting Started" section
  • Included all FAQs from INFERENG-1867

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Summary of Changes

Hello @cajeonrh, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new Frequently Asked Questions (FAQ) page within the "Getting Started" section of the documentation. The primary goal is to centralize answers to common user queries about the LLM Compressor, thereby enhancing user self-service and clarity on topics such as model performance post-compression, integration with other tools like sglang, and practical guidance on compression strategies and memory requirements.

Highlights

  • New FAQ Page: A new Frequently Asked Questions (FAQ) page has been added to the documentation.
  • Comprehensive Coverage: The FAQ page addresses common questions regarding LLM Compressor, including performance expectations after compression, sglang integration, compression strategy selection, memory usage, and specifics on which layers to quantize.
  • Resource Links: The page provides direct links to relevant guides and code examples for users seeking more in-depth information on various topics.
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Code Review

This pull request adds a new FAQ page, which is a great addition to the documentation. The content is relevant and covers important user questions. I've identified a few areas for improvement, mainly related to Markdown link formatting, content clarity, and consistency. There are several instances of incorrect link syntax that need to be fixed across the document. I've also suggested consolidating a couple of redundant questions and using relative paths for internal links to improve maintainability.

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Thanks Cassie! Added a couple suggestions below.

Also some of your links are incorrectly formatted. It should be [link text](link url)

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cajeonrh commented Oct 2, 2025

Thanks Fynn! I've incorporated your feedback.

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Looks good! one comment to add a note on multimodal models for question 5

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fynnsu commented Oct 2, 2025

Screenshot 2025-10-02 at 3 32 32 PM

In the sidebar we're getting this title for the page. Can we simplify this to just "Frequently Asked Questions" or maybe even "FAQ". I believe this is being set by the # header at the top of the file

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fynnsu commented Oct 2, 2025

Screenshot 2025-10-02 at 3 34 58 PM

Also on the "Getting Started" page we have these boxes for "Installation", "Compress Your Model" and "Deploy on vLLM". Could we add a box for FAQ?

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Could we add a quick question on installation: vLLM and llmcompressor should be used in separate environments as they may have dependency mismatches?

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The other common question we get asked is about multi-gpu support.

Can we add the following?

  1. LLM Compresor handles all gpu movement for you.
  2. For data-free pathways, we leverage all available gpus and offload anything that doesnt fit onto the allocated gpus. If using pathways that require data, we sequentially onload model layers onto a single gpu. This is the case for LLM Compressor 0.6-0.8.

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cajeonrh commented Oct 6, 2025

I've incorporated feedback, added more questions, and also added a FAQ box on the Getting Started page. Please let me know if I missed anything.

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fynnsu previously approved these changes Oct 6, 2025
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Looks great! Thanks for making those changes!

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fynnsu commented Oct 6, 2025

Looks like you need to fix DCO though. There are some instructions here: https://github.com/vllm-project/llm-compressor/pull/1896/checks?check_run_id=52066401360.

@cajeonrh cajeonrh requested a review from dsikka October 6, 2025 20:44
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I'm really not a fan of using casual pronouns like "us", "we", "my". This may sound pedantic, but speaking from personal experience contributing to other OSS repos, words like "we" have the effect of alienating open source contributors. LLM Compressor is owned by everyone, the RedHat/ LLM Compressor team helps to maintain and shepherd it.

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We should add a section titled "Where can I learn more about LLM Compressor?" which links to talks we've given.

https://www.youtube.com/watch?v=caLYSZMVQ1c
https://www.youtube.com/watch?v=GrhuqQDmBk8
https://www.youtube.com/watch?v=WVenRmF4dPY
https://www.youtube.com/watch?v=G1WNlLxPLSE


**7. Does LLM Compressor have multi-GPU support?**

LLM Compressor handles all GPU movement for you. For data-free pathways, we leverage all available GPUs and offload anything that doesn't fit onto the allocated GPUs. If you are using pathways that require data, we sequentially onload model layers onto a single GPU. This is the case for LLM Compressor 0.6-0.8.
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We essentially do not have mult-GPU support right now.

#1809

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dispatch_for_generation is used for data-free atm?

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Is this FAQ still relevant then? Should I remove it or does it need to be changed?

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Still relevant

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** 7. Does LLM Compressor support compressing large models? **

LLM Compressor enables the compression of large models via sequential onloading, whereby layers of the model are jointly onloaded to a single GPU, optimized, then offloaded back to the CPU. While this is the default data pipeline for most cases, you can override this setting for slightly better runtime by using oneshot(..., pipeline="basic") if you model can fit across all GPU resources. Multi-GPU parallel optimization is currently in development and being tracked here.

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I think we need to add a point re: data free pathways for FP8 quantization @kylesayrs

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Also, we need to keep the original question as most users ask about mutli-gpu support specifically / are confused when they only see one active gpu

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Hm, maybe something like this

** 7. Does LLM Compressor have multi-GPU support? **

LLM Compressor enables the compression of large models via sequential onloading, whereby layers of the model are jointly onloaded to a single GPU, optimized, then offloaded back to the CPU. This is why, in most cases, only one GPU is used at a time.

In cases where no calibration data is needed, the model is dispatched to all GPUs, although only one GPU is used at a time for compression.

Multi-GPU parallel optimization is currently in development and being tracked here.

Signed-off-by: Cassie Jeon <cajeon@redhat.com>
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cajeonrh commented Oct 10, 2025

I'm really not a fan of using casual pronouns like "us", "we", "my". This may sound pedantic, but speaking from personal experience contributing to other OSS repos, words like "we" have the effect of alienating open source contributors. LLM Compressor is owned by everyone, the RedHat/ LLM Compressor team helps to maintain and shepherd it.

@kylesayrs
I think this would need consensus from the team before changing it. I went through the LLM Compressor docs and there are about 35 pages that use the pronouns "we"/"us." Unless the FAQ page should be the only one that doesn't use any personal pronouns. Otherwise, if the change needs to be applied to all the pages for LLM Compressor, that should be a new ticket for the work.

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@cajeonrh That’s fine, we can table the discussion for now

@dsikka dsikka requested a review from kylesayrs October 14, 2025 14:07
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LGTM, one question on links but we can revisit in a follow-up


**5. What layers should be quantized?**

Typically, all linear layers are quantized except the `lm_head` layer. This is because the `lm_head` layer is the last layer of the model and sensitive to quantization, which will impact the model's accuracy. For example, [this code snippet shows how to ignore the lm_head layer](https://github.com/vllm-project/llm-compressor/blob/main/examples/quantization_w8a8_fp8/llama3_example.py#L18).
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This link and the one below might become stale if those files are ever changed, since they point to a file on main that can be changed. Should we use a tagged version instead?

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