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[Attention] Refactor CUDA attention backend selection logic #24794

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[Attention] Refactor CUDA attention backend selection logic #24794

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@MatthewBonanni MatthewBonanni commented Sep 13, 2025 •
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Purpose

CudaPlatformBase.get_attention_backend_cls has gotten complex and messy over time. This PR cleans up the logic (without changing the behavior) and standardizes the interface.

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  • The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
  • The test plan, such as providing test command.
  • The test results, such as pasting the results comparison before and after, or e2e results
  • (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
  • (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

@mergify mergify bot added rocm Related to AMD ROCm speculative-decoding v1 tpu Related to Google TPUs labels Sep 13, 2025
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mergify bot commented Sep 13, 2025

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @MatthewBonanni.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

@mergify mergify bot added the needs-rebase label Sep 13, 2025
njhill
njhill reviewed Sep 13, 2025
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@MatthewBonanni MatthewBonanni changed the title [Attention] Refactor CUDA attention backend selection logic [WIP][Attention] Refactor CUDA attention backend selection logic Sep 13, 2025
@MatthewBonanni MatthewBonanni changed the title [WIP][Attention] Refactor CUDA attention backend selection logic [Attention] Refactor CUDA attention backend selection logic Sep 16, 2025
@MatthewBonanni MatthewBonanni marked this pull request as ready for review September 16, 2025 13:22
@mergify mergify bot removed the needs-rebase label Sep 16, 2025
@MatthewBonanni
Merge branch 'main' into backend_selection_refactor
54dffe2 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@mergify mergify bot removed the needs-rebase label Oct 30, 2025
ProExpertProg
ProExpertProg reviewed Oct 31, 2025
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Thanks for the cleanup, mostly nits and structure comments

MatthewBonanni and others added 8 commits October 31, 2025 08:52
@MatthewBonanni
add test_attention_selector to Blackwell Tests
d34eb77 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
rename _Backend to AttentionBackendEnum, add class methods
48290ee 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
get rid of get_min_compute_capability and get_max_compute_capability
1c71eab 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
fix pre-commit
6e9d1f1 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
change methods to properties
d3cdda7 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
device_capability not None
925069c 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
query device_capability inside get_required_kv_cache_layout
a0b56c5 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni @ProExpertProg
Update vllm/attention/backends/abstract.py
fff453a 
Co-authored-by: Luka Govedič <ProExpertProg@users.noreply.github.com>
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
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@ProExpertProg thanks for your review! I've addressed your comments

ProExpertProg
ProExpertProg approved these changes Oct 31, 2025
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@github-project-automation github-project-automation bot moved this from To Triage to Ready in gpt-oss Issues & Enhancements Oct 31, 2025
@MatthewBonanni
class_path always None in decorator
530f356 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
type hint for value
933ee5f 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
restore comment
255edc9 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@MatthewBonanni
Merge branch 'main' into backend_selection_refactor
6af36aa
@MatthewBonanni
fix docs
c9d62f8 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
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mergify bot commented Oct 31, 2025

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @MatthewBonanni.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

@mergify mergify bot added the needs-rebase label Oct 31, 2025
@MatthewBonanni
Merge branch 'main' into backend_selection_refactor
93a0770 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@mergify mergify bot removed the needs-rebase label Oct 31, 2025
@MatthewBonanni
add FLASHMLA_SPARSE to priority list
f6a5a32 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
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mergify bot commented Oct 31, 2025

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @MatthewBonanni.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

@mergify mergify bot added the needs-rebase label Oct 31, 2025
@MatthewBonanni
Merge branch 'main' into backend_selection_refactor
bc91050 
Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
@mergify mergify bot removed the needs-rebase label Oct 31, 2025
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ci/build deepseek Related to DeepSeek models documentation Improvements or additions to documentation frontend gpt-oss Related to GPT-OSS models kv-connector multi-modality Related to multi-modality (#4194) new-model Requests to new models performance Performance-related issues qwen Related to Qwen models ready ONLY add when PR is ready to merge/full CI is needed rocm Related to AMD ROCm speculative-decoding structured-output tpu Related to Google TPUs v1

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@MatthewBonanni @ILikeIneine @mgoin @NickLucche @ProExpertProg @njhill