[AMD] Update MiniMax-M3-MXFP4 MI355X vLLM disagg perf and config

[Duyi-Wang]

Changes

• Prefill-only INT4 quick-reduce: set VLLM_ROCM_QUICK_REDUCE_QUANTIZATION=INT4 and VLLM_ROCM_QUICK_REDUCE_MAX_SIZE_BYTES_MB=2048 on the prefill workers, via a new prefill_env channel in server_vllm.sh (mirrors the existing decode_env path; injected on every prefill rank). Applied to the MiniMax-M3-MXFP4 entry in models_vllm.yaml.
• Search space: cap the 1P1D TP4 concurrency sweep at 256 (was 512). 2P1D TP4 unchanged at 128/256/512.

Notes

• Quick-reduce is prefill-only (the all-reduce path); decode is unaffected.
• Single commit on top of main; perf-changelog.yaml entry included.

[github-actions]

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[claude]

Claude finished @Duyi-Wang's task in 1m 3s —— View job

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PR Review

• Gather context (diff, server_vllm.sh, models_vllm.yaml, perf-changelog.yaml)
• Verify prefill_env injection mirrors decode_env
• Validate master-config + perf-changelog rules

LGTM — no blocking issues found.

Verified:

• The new prefill_env / PREFILL_MODEL_ENVS channel correctly mirrors the existing decode_env path. It's injected on all prefill ranks — node 0 (proxy+prefill, server_vllm.sh:256) and additional prefill nodes 1..xP-1 (server_vllm.sh:430) — before each vllm serve prefill command. The for env_pair in ${PREFILL_MODEL_ENVS}; do export "$env_pair" pattern word-splits the two KEY=VALUE pairs correctly. Decode is untouched, matching the "prefill-only" intent.
• amd-master.yaml was modified and perf-changelog.yaml was updated — the new entry is correctly appended to the end of the file (after PR [codex] add MiniMax M3 FP4 MI355X vLLM MTP benchmark #1939's entry).
• The minimaxm3-fp4-mi355x-vllm-disagg config key is pre-existing (only the conc-list was edited 512→256), so no new model-prefix concern introduced here.

[functionstackx]

can u update this an upstream docker image such that it is a performance update PR? @Duyi-Wang

[Duyi-Wang]

Ok, the image will be updated once all optimizations have been merged.