### What this PR does / why we need it?
maybe fixes
[#1728](https://github.com/vllm-project/vllm-ascend/issues/1728#issuecomment-3065083433)
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Test Qwen3-32B tp=4 with:
```bash
vllm serve --port 1234 Qwen/Qwen3-32B \
--served-model-name Qwen3-32B \
--tensor-parallel-size 4 \
--swap-space 16 \
--max-model-len 6000 \
--load-format dummy \
--disable-log-stats \
--disable-log-requests \
```
Request batch_size=128 input/output token=1024
**In 0.9.2rc1**
```text
=====================================================
Total TPS with prefill(tokens/s) : 785.1395
Total TPS without prefill : 846.6809
Mean TPS with prefill : 6.1339
Mean TPS without prefill : 6.6147
=====================================================
Mean TTFT(ms) : 10307.8123
Max TTFT(ms) : 21423.0733
Min TTFT(ms) : 362.3602
=====================================================
Mean TPOT(ms) : 151.3051
Max TPOT(ms) : 159.4649
Min TPOT(ms) : 140.899
=====================================================
Total Time(s) : 175.6032
Request Throughput(requests/s) : 0.7289
=====================================================
```
**Apply this PR**
```text
=====================================================
Total TPS with prefill(tokens/s) : 811.0014
Total TPS without prefill : 876.4423
Mean TPS with prefill : 6.3359
Mean TPS without prefill : 6.8472
=====================================================
Mean TTFT(ms) : 10263.8382
Max TTFT(ms) : 21151.2547
Min TTFT(ms) : 375.9136
=====================================================
Mean TPOT(ms) : 146.1686
Max TPOT(ms) : 154.0957
Min TPOT(ms) : 136.8879
=====================================================
Total Time(s) : 169.8579
Request Throughput(requests/s) : 0.7536
=====================================================
```
The TPOT performance gap between these two sets of data is about 3%.
- vLLM version: v0.9.2
- vLLM main:
8dfb45ca33
Signed-off-by: lianyibo <lianyibo1@kunlunit.com>
53d2ea3789