…(#7603)
### What this PR does / why we need it?
Block verify uses cumprod(target_probs / draft_probs) for joint
acceptance. Suffix/ngram methods have
draft_probs=None, the fallback draft_token_probs=1.0 with cumprod is not
equivalent to per-token
verification, causing incorrect accept/reject results. Fix:
using_block_verify = max_spec_len >= 3 and draft_probs is not None.
MTP/Eagle3 unaffected.
- vLLM version: v0.18.0
- vLLM main:
ed359c497a
<!-- Thanks for sending a pull request!
BEFORE SUBMITTING, PLEASE READ
https://docs.vllm.ai/en/latest/contributing/overview.html
-->
### What this PR does / why we need it?
<!--
- Please clarify what changes you are proposing. The purpose of this
section is to outline the changes and how this PR fixes the issue.
If possible, please consider writing useful notes for better and faster
reviews in your PR.
- Please clarify why the changes are needed. For instance, the use case
and bug description.
- Fixes #
-->
### Does this PR introduce _any_ user-facing change?
<!--
Note that it means *any* user-facing change including all aspects such
as API, interface or other behavior changes.
Documentation-only updates are not considered user-facing changes.
-->
### How was this patch tested?
<!--
CI passed with new added/existing test.
If it was tested in a way different from regular unit tests, please
clarify how you tested step by step, ideally copy and paste-able, so
that other reviewers can test and check, and descendants can verify in
the future.
If tests were not added, please describe why they were not added and/or
why it was difficult to add.
-->
Signed-off-by: liuchenbing <chenliumail@163.com>
Co-authored-by: liuchenbing <chenliumail@163.com>
2a0a588311