[MoE] enable all2all fi_one_sided by default

[arpera]

Purpose

Enable flashinfer_nvlink_one_sided backend for all2all by default. As performance e2e tests show, flashinfer_nvlink_one_sided outperforms current default backend for all2all allgather_reducescatter by 8% on disaggregated serving of Qwen3.5 397B NVFP4.

Test Result

Disaggregated serving of Qwen3.5 397B NVFP4 on GB200 cluster

Recipe for srt-slurm: agrs-qwen35-disagg-gb200.yaml

============ Serving Benchmark Result ============
Successful requests:                     16384
Benchmark measurement start (UTC):       2026-08-21T13:58:46.909140+00:00
Benchmark measurement end (UTC):         2026-08-21T14:04:17.983068+00:00
Benchmark duration (s):                  331.07
Total input tokens:                      134217728
Total generated tokens:                  16777216
Request throughput (req/s):              49.49
Output token throughput (tok/s):         50675.14
Peak output token throughput (tok/s):    55616.60
Total Token throughput (tok/s):          456076.23
---------------Time to First Token----------------
Mean TTFT (ms):                          3617.93
Median TTFT (ms):                        1164.76
P99 TTFT (ms):                           33376.05
-----Time per Output Token (excl. 1st token)------
Mean TPOT (ms):                          35.46
Median TPOT (ms):                        36.54
P99 TPOT (ms):                           36.58
---------------Inter-token Latency----------------
Mean ITL (ms):                           3297.61
Median ITL (ms):                         3649.41
P99 ITL (ms):                            3674.07
----------------End-to-end Latency----------------
Mean E2EL (ms):                          39891.64
Median E2EL (ms):                        38481.03
P99 E2EL (ms):                           69761.65
==================================================

Recipe for srt-slurm: onesided-qwen35-disagg-gb200.yaml

============ Serving Benchmark Result ============
Successful requests:                     16380
Benchmark measurement start (UTC):       2026-08-21T13:55:26.660008+00:00
Benchmark measurement end (UTC):         2026-08-21T14:00:30.608585+00:00
Benchmark duration (s):                  303.95
Total input tokens:                      134184960
Total generated tokens:                  16773120
Request throughput (req/s):              53.89
Output token throughput (tok/s):         55184.07
Peak output token throughput (tok/s):    61702.70
Total Token throughput (tok/s):          496656.66
---------------Time to First Token----------------
Mean TTFT (ms):                          6216.73
Median TTFT (ms):                        3186.26
P99 TTFT (ms):                           33960.10
-----Time per Output Token (excl. 1st token)------
Mean TPOT (ms):                          29.21
Median TPOT (ms):                        30.31
P99 TPOT (ms):                           30.54
---------------Inter-token Latency----------------
Mean ITL (ms):                           2716.92
Median ITL (ms):                         3030.37
P99 ITL (ms):                            3062.17
----------------End-to-end Latency----------------
Mean E2EL (ms):                          36102.81
Median E2EL (ms):                        34085.26
P99 E2EL (ms):                           62558.25
==================================================

Total Token throughput +8% for flashinfer_nvlink_one_sided.

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[github-actions]

✅ @arpera, CI is now available for this PR.

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