Skip to content

[Revert] Fix performance regression for GLM-4.7-GPTQ decode and MTP acceptance rate#33771

Merged
LucasWilkinson merged 2 commits intovllm-project:mainfrom
aabbccddwasd:perf-regression-fix
Feb 8, 2026
Merged

[Revert] Fix performance regression for GLM-4.7-GPTQ decode and MTP acceptance rate#33771
LucasWilkinson merged 2 commits intovllm-project:mainfrom
aabbccddwasd:perf-regression-fix

Conversation

@aabbccddwasd
Copy link
Contributor

@aabbccddwasd aabbccddwasd commented Feb 4, 2026

Purpose

Fix performance regressions introduced by two recent commits:

Affected Model: GLM-4.7-GPTQ-INT4-INT8MIX

  • Model body: int4/int8 mixed quantization
  • MTP module (layer 92): manually configured as unquantized BF16 to increase acceptance rate

Test Plan

Performance Impact

The following benchmark data was collected on 4×RTX PRO 6000 BLACKWELL GPUs:

Configuration Throughput Delta
v0.13.0 (no regression) + quantized MTP 90 tps -
v0.13.0 + BF16 MTP 95 tps baseline
e0327c9 + BF16 MTP 86 tps -9.5%
654a71f + BF16 MTP 77 tps -19.0%
After revert + BF16 MTP 95 tps ✅ recovered

Validation

  1. Model: GLM-4.7-GPTQ-INT4-INT8MIX with unquantized MTP (BF16)
  2. Hardware: 4×RTX PRO 6000 BLACKWELL
  3. Kernel selection verified:
    • Quantized layers: Marlin kernels
    • Unquantized MTP: fused_triton kernels (restored)

Test Result

Performance recovered: Throughput restored from 77 tps back to 95 tps
MTP acceptance rate restored: ~30% improvement
Kernel selection corrected: Unquantized MTP now correctly uses fused_triton kernel

Note: Performance data was measured without optimized Triton configuration files. Additional performance gains are expected with proper Triton optimizations.


Essential Elements of an Effective PR Description Checklist
  • 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.

@github-actions
Copy link

github-actions bot commented Feb 4, 2026

👋 Hi! Thank you for contributing to the vLLM project.

💬 Join our developer Slack at https://slack.vllm.ai to discuss your PR in #pr-reviews, coordinate on features in #feat- channels, or join special interest groups in #sig- channels.

Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run fastcheck CI which starts running only a small and essential subset of CI tests to quickly catch errors.

You ask your reviewers to trigger select CI tests on top of fastcheck CI.

Once the PR is approved and ready to go, your PR reviewer(s) can run CI to test the changes comprehensively before merging.

To run CI, PR reviewers can either: Add ready label to the PR or enable auto-merge.

If you have any questions, please reach out to us on Slack at https://slack.vllm.ai.

🚀

@mergify
Copy link

mergify bot commented Feb 4, 2026

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

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

Copy link
Contributor

@gemini-code-assist gemini-code-assist bot left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Code Review

This pull request correctly reverts two previous commits that introduced performance regressions. The changes are consistent across all affected files, removing the problematic code related to on-device attention metadata computation and a temporary workaround for MoE layer compilation. The detailed description, including benchmark data, clearly justifies the revert. This is a solid contribution to restore performance and improve codebase maintainability. I find no issues with the changes.

@mergify
Copy link

mergify bot commented Feb 4, 2026

Hi @aabbccddwasd, the pre-commit checks have failed. Please run:

uv pip install pre-commit
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy or markdownlint failing?
mypy and markdownlint are run differently in CI. If the failure is related to either of these checks, please use the following commands to run them locally:
# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10
# For markdownlint
pre-commit run --hook-stage manual markdownlint

@aabbccddwasd
Copy link
Contributor Author

aabbccddwasd commented Feb 4, 2026

Note on MTP Performance Fix

The MTP acceptance rate regression from commit 654a71f (#32805) has been
addressed by PR #33624, which disables the problematic fast_moe_cold_start
optimization when speculative decoding is enabled.

@mergify
Copy link

mergify bot commented Feb 4, 2026

Hi @aabbccddwasd, the pre-commit checks have failed. Please run:

uv pip install pre-commit
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy or markdownlint failing?
mypy and markdownlint are run differently in CI. If the failure is related to either of these checks, please use the following commands to run them locally:
# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10
# For markdownlint
pre-commit run --hook-stage manual markdownlint

Copy link
Collaborator

@LucasWilkinson LucasWilkinson left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

please restrict the revert to flashinfer.py, we are still planning to deprecate these properties

@aabbccddwasd
Copy link
Contributor Author

please restrict the revert to flashinfer.py, we are still planning to deprecate these properties

Fixed

@aabbccddwasd
Copy link
Contributor Author

@LucasWilkinson

@github-project-automation github-project-automation bot moved this from In review to Ready in NVIDIA Feb 7, 2026
@LucasWilkinson LucasWilkinson enabled auto-merge (squash) February 7, 2026 13:46
@github-actions github-actions bot added the ready ONLY add when PR is ready to merge/full CI is needed label Feb 7, 2026
This reverts the change in vllm-project#31773 that replaced seq_lens_cpu with
seq_lens.cpu() in the FlashInfer backend. The property access provides
better performance by avoiding unnecessary D2H transfers when the cached
value is already available.

Fixes performance regression on GLM-4.7-GPTQ-INT4-INT8MIX model with
MTP (Multi-Token Prediction) enabled, where throughput dropped from
95 to 77 tps.

Signed-off-by: aabbccddwasd <aabbccddwasd@qq.com>
auto-merge was automatically disabled February 8, 2026 05:49

Head branch was pushed to by a user without write access

@aabbccddwasd
Copy link
Contributor Author

@LucasWilkinson I'm sorry but my claude code accidentally disabled auto-merge when I try to reslove conflicts. could you help me to merge it?

@LucasWilkinson LucasWilkinson merged commit 179ae7d into vllm-project:main Feb 8, 2026
53 checks passed
@github-project-automation github-project-automation bot moved this from Ready to Done in NVIDIA Feb 8, 2026
@voipmonitor
Copy link
Contributor

voipmonitor commented Feb 8, 2026

  1. Model: GLM-4.7-GPTQ-INT4-INT8MIX with unquantized MTP (BF16)

I'm curious - why not NVFP4 version on rtx6000 pro?

@aabbccddwasd
Copy link
Contributor Author

  1. Model: GLM-4.7-GPTQ-INT4-INT8MIX with unquantized MTP (BF16)

I'm curious - why not NVFP4 version on rtx6000 pro?

1.bad performance ( around 60tps ), but may improve after #33417, but I don't think it can beat optimized MarlinGPTQ
2.(important) GLM-4.7-GPTQ-INT4-INT8MIX perserved all attention and shared experts in fp8 precision, I belive it may perform better in long content scenarios like code agent

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

nvidia ready ONLY add when PR is ready to merge/full CI is needed v1

Projects

Status: Done

Development

Successfully merging this pull request may close these issues.

3 participants