Use AITER Backend for Dsv4

[JadenMathias]

Purpose

Moves reliance away from gpt oss triton kernels and uses a new moe aiter backend

gsm8k lm_eval — 455_wip vs 455_dsv4_aiter_backend_clean

Setup: via benchmarks/vllm_smoketest.sh.

Summary

Model	Backend (aiter)	455_wip	This Branch
dsv4f (temp=0)	AITER_MXFP4_BF16	0.96	0.96
dsv4f (temp=1)	AITER_MXFP4_BF16	0.96	0.97
gptoss	AITER_MXFP4_FP8	0.91	0.89
dsr1	AITER_MXFP4_MXFP4	0.73	0.77
minimax	EMULATION	0.92	0.92

Detailed (flexible-extract / strict-match)

455_wip (baseline, reference config) — dsv4f = A4W4=1 + --moe-backend TRITON_UNFUSED

Model	Backend	Decoding	flexible	strict
gptoss	AITER_MXFP4_FP8	greedy t=0	0.91 ±0.0288	0.16 ±0.0368
dsr1	AITER_MXFP4_MXFP4	sampling t=0.6	0.73 ±0.0446	0.72 ±0.0451
dsv4f	TRITON_UNFUSED	sampling t=1.0	0.96 ±0.0197	0.96 ±0.0197
minimax	EMULATION	sampling t=1.0	0.92 ±0.0273	0.91 ±0.0288

455_dsv4_aiter_backend_clean (with fix)

Model	Backend	Decoding	flexible	strict
dsv4f	AITER_MXFP4_BF16	greedy t=0	0.96 ±0.0197	0.96 ±0.0197
dsv4f	AITER_MXFP4_BF16	sampling t=1.0	0.97 ±0.0171	0.97 ±0.0171
gptoss	AITER_MXFP4_FP8	greedy t=0	0.89 ±0.0314	0.19 ±0.0394
dsr1	AITER_MXFP4_MXFP4	sampling t=0.6	0.77 ±0.0423	0.77 ±0.0423
minimax	EMULATION	sampling t=1.0	0.92 ±0.0273	0.91 ±0.0288

vllm bench serve — aiter branch (gfx1250)

Serving benchmark, random dataset, 1024 in / 1024 out, num_prompts=10,
max_concurrency=1, request_rate=inf, ignore_eos=True. All runs 10/10
successful (0 failed).

Model	MoE backend	Output tok/s	Total tok/s	Median TTFT (ms)	Median TPOT (ms)	Median ITL (ms)	Duration (s)
gptoss	AITER_MXFP4_FP8	177.92	355.84	38.33	5.59	5.59	57.55
dsr1	AITER_MXFP4_MXFP4	48.85	97.69	195.76	20.27	20.27	209.64
dsv4f	AITER_MXFP4_BF16	7.38	14.75	379.28	135.34	135.33	1388.37
minimax	—	2.12	4.24	852.48	471.27	471.27	4831.74

Raw Serving Benchmark Result blocks

gptoss — AITER_MXFP4_FP8

Successful requests:                     10
Failed requests:                         0
Maximum request concurrency:             1
Benchmark duration (s):                  57.55
Total input tokens:                      10240
Total generated tokens:                  10240
Request throughput (req/s):              0.17
Output token throughput (tok/s):         177.92
Total token throughput (tok/s):          355.84
Mean/Median/P99 TTFT (ms):               41.17 / 38.33 / 64.88
Mean/Median/P99 TPOT (ms):               5.59 / 5.59 / 5.59
Mean/Median/P99 ITL (ms):                5.59 / 5.59 / 5.70

dsr1 — AITER_MXFP4_MXFP4

Successful requests:                     10
Failed requests:                         0
Maximum request concurrency:             1
Benchmark duration (s):                  209.64
Total input tokens:                      10240
Total generated tokens:                  10240
Request throughput (req/s):              0.05
Output token throughput (tok/s):         48.85
Total token throughput (tok/s):          97.69
Mean/Median/P99 TTFT (ms):               223.51 / 195.76 / 450.61
Mean/Median/P99 TPOT (ms):               20.27 / 20.27 / 20.29
Mean/Median/P99 ITL (ms):                20.27 / 20.27 / 20.56

dsv4f — AITER_MXFP4_BF16

Successful requests:                     10
Failed requests:                         0
Maximum request concurrency:             1
Benchmark duration (s):                  1388.37
Total input tokens:                      10240
Total generated tokens:                  10240
Request throughput (req/s):              0.01
Output token throughput (tok/s):         7.38
Total token throughput (tok/s):          14.75
Mean/Median/P99 TTFT (ms):               381.42 / 379.28 / 402.90
Mean/Median/P99 TPOT (ms):               135.34 / 135.35 / 135.39
Mean/Median/P99 ITL (ms):                135.34 / 135.33 / 136.07

minimax

Successful requests:                     10
Failed requests:                         0
Maximum request concurrency:             1
Benchmark duration (s):                  4831.74
Total input tokens:                      10240
Total generated tokens:                  10240
Request throughput (req/s):              0.00
Output token throughput (tok/s):         2.12
Total token throughput (tok/s):          4.24
Mean/Median/P99 TTFT (ms):               851.03 / 852.48 / 857.60
Mean/Median/P99 TPOT (ms):               471.48 / 471.27 / 472.69
Mean/Median/P99 ITL (ms):                471.48 / 471.27 / 473.49