[TRTLLM-13017][fix] disagg gen init: use prompt_len for SWA history_length#14627
Merged
pcastonguay merged 1 commit intoMay 27, 2026
Conversation
Shixiaowei02
requested review from
a team,
Tabrizian and
joyang-nv
and removed request for
a team
jiaganc
reviewed
May 27, 2026
Shixiaowei02
changed the title
Shixiaowei02
changed the title
Collaborator
|
/bot run |
Collaborator
|
PR_Github #50529 [ run ] triggered by Bot. Commit: |
For a disagg gen init request entering the V2 scheduler, context_current_position is still 0 — it is only advanced to prompt_len in _prepare_disagg_gen_transmission_complete after KV transfer completes. Passing history_length=context_current_position degenerates to history_length=0, the SWA stale range collapses to an empty interval, and pre-window blocks are still allocated before KV transfer — defeating the over-allocation fix from NVIDIA#13845/NVIDIA#14377. Use req.prompt_len, which is known statically at scheduler time and correctly conveys that the entire prompt is history. Signed-off-by: Shixiaowei02 <39303645+Shixiaowei02@users.noreply.github.com>
Shixiaowei02
force-pushed
the
fix/disagg-gen-init-swa-prompt-len
branch
from
e834dbd to
0f2294e
Compare
Collaborator
Author
|
/bot run --add-multi-gpu-test --disable-fail-fast |
Collaborator
|
PR_Github #50546 [ run ] triggered by Bot. Commit: |
pcastonguay
approved these changes
May 27, 2026
Collaborator
|
PR_Github #50529 [ run ] completed with state |
Collaborator
|
/bot run --add-multi-gpu-test --disable-fail-fast |
Collaborator
|
PR_Github #50570 [ run ] triggered by Bot. Commit: |
Collaborator
|
PR_Github #50546 [ run ] completed with state |
peihu-nv
approved these changes
May 27, 2026
Collaborator
|
PR_Github #50570 [ run ] completed with state |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
6 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
For a disagg gen init request entering the V2 scheduler, context_current_position is still 0 — it is only advanced to prompt_len in _prepare_disagg_gen_transmission_complete after KV transfer completes. Passing history_length=context_current_position degenerates to history_length=0, the SWA stale range collapses to an empty interval, and pre-window blocks are still allocated before KV transfer — defeating the over-allocation fix from #13845/#14377.
Use req.prompt_len, which is known statically at scheduler time and correctly conveys that the entire prompt is history.
@coderabbitai summary
Description
Test Coverage
PR Checklist
Please review the following before submitting your PR:
PR description clearly explains what and why. If using CodeRabbit's summary, please make sure it makes sense.
PR Follows TRT-LLM CODING GUIDELINES to the best of your knowledge.
Test cases are provided for new code paths (see test instructions)
If PR introduces API changes, an appropriate PR label is added - either
api-compatibleorapi-breaking. Forapi-breaking, includeBREAKINGin the PR title.Any new dependencies have been scanned for license and vulnerabilities
CODEOWNERS updated if ownership changes
Documentation updated as needed
Update tava architecture diagram if there is a significant design change in PR.
The reviewers assigned automatically/manually are appropriate for the PR.
Please check this after reviewing the above items as appropriate for this PR.
GitHub Bot Help
To see a list of available CI bot commands, please comment
/bot help.