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[ROCm][PERF] Enable AITER PA gluon decode for MiniMax-M3 MTP and dense layers - #52849

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[ROCm][PERF] Enable AITER PA gluon decode for MiniMax-M3 MTP and dense layers#52849
ukannika wants to merge 5 commits into
vllm-project:mainfrom
ukannika:amd/minimax_m3_enable_pa_gluon

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@ukannika

@ukannika ukannika commented Aug 19, 2026

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Purpose

The gluon paged-attention decode kernel handles multi-token query lengths, so
EAGLE3 speculative decoding no longer has to fall back to native vllm unified_attention.

Test Plan

Server cmd to run EAGLE3 speculative decoding

export VLLM_ENGINE_READY_TIMEOUT_S=3600
export VLLM_EXECUTE_MODEL_TIMEOUT_SECONDS=1800
export VLLM_USE_BREAKABLE_CUDAGRAPH=0
export VLLM_ROCM_USE_AITER=1
export VLLM_ROCM_USE_AITER_MOE=1
export VLLM_ROCM_USE_AITER_FUSION_SHARED_EXPERTS=1
export VLLM_ROCM_QUICK_REDUCE_QUANTIZATION=INT4
export VLLM_ROCM_QUICK_REDUCE_CAST_BF16_TO_FP16=0
export VLLM_ROCM_QUICK_REDUCE_QUANTIZATION_MIN_SIZE_KB=256
export VLLM_ROCM_SHUFFLE_KV_CACHE_LAYOUT=1
export VLLM_CUSTOM_SCOPES_FOR_PROFILING=1

vllm serve amd/MiniMax-M3-MXFP4  \
--served-model-name MiniMaxAI/MiniMax-M3 \
--port 8888 \
--tensor-parallel-size 4 \
--trust-remote-code \
--block-size 128 \
--enable-prefix-caching \
--enable-chunked-prefill \
--language-model-only \
--max-num-batched-tokens 65536 \
--default-chat-template-kwargs '{"thinking_mode":"enabled"}' \
--max-num-seqs 128 \
--kv-cache-dtype fp8 \
--attention-backend ROCM_AITER_FA \
--moe-backend aiter \
--reasoning-parser minimax_m3 \
--speculative-config '{"method": "eagle3", "model": "Inferact/MiniMax-M3-EAGLE3-GQA", "num_speculative_tokens": 3, "attention_backend": "ROCM_AITER_FA"}'

Test Result

MiniMax-M3 with EAGLE3 3-token speculative decoding sees a significant uplift at long context: the AITER gluon paged-attention kernel replaces the unified_attention fallback and is substantially faster for longer contexts.
Accuracy score:

Tasks Version Filter n-shot Metric Value Stderr
gsm8k 3 flexible-extract 5 exact_match 0.9689 ± 0.0048
strict-match 5 exact_match 0.9689 ± 0.0048

ukannika and others added 2 commits August 18, 2026 17:16
Signed-off-by: ukannika <uma.kannikanti@amd.com>
Signed-off-by: ykamiset <yaminipreethi.kamisetty@amd.com>

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This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

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@mergify mergify Bot added the rocm Related to AMD ROCm label Aug 19, 2026
@github-project-automation github-project-automation Bot moved this to Todo in AMD Aug 19, 2026
@Rohan138

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minor q @ukannika can you include your env vars for AITER, shuffle KV cache, etc. in the repro command above?

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LGTM but cc @tjtanaa for the ROCM_AITER_FA changes/ @jhu960213 for the kv cache layout

Signed-off-by: ykamiset <yaminipreethi.kamisetty@amd.com>
@dllehr-amd

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hey @ukannika Can you check pre-commit locally really quick? I know it's not running here, but I think there may be some errors

@ukannika

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hey @ukannika Can you check pre-commit locally really quick? I know it's not running here, but I think there may be some errors

checking now. thank you for reviewing.

@mergify mergify Bot added the minimax label Aug 19, 2026
@ukannika
ukannika requested a review from njhill as a code owner August 20, 2026 02:17
@ukannika

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hey @ukannika Can you check pre-commit locally really quick? I know it's not running here, but I think there may be some errors

Sorry for that. we missed to push some code change. Fixed now. Thank you

raise ValueError("Block size must be a multiple of 16.")

if rocm_aiter_ops.is_shuffle_kv_cache_enabled():
return (num_blocks, 2, block_size, num_kv_heads, head_size)

@tjtanaa tjtanaa Aug 20, 2026

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Should we update this?

get_kv_cache_shape is used by gpu runner to determine how the kvcache is packed in the kvcache buffers/pool/management system. It is not referring to the kvcache shape expect by the kernels.

The KVCACHE is reshaped on the fly in the attention forward pass from (num_blocks, num_kv_heads, block_size, 2 * head_size) to (num_blocks, 2, block_size, num_kv_heads, head_size) every time.

                    num_blocks, block_size, num_kv_heads, _ = key_cache.shape
                    x = 16 // key_cache.element_size()
                    new_key_cache = key_cache.reshape(
                        num_blocks, num_kv_heads, head_size // x, block_size, x
                    )
                    new_value_cache = value_cache.reshape(
                        num_blocks, num_kv_heads, block_size // x, head_size, x
                    )

However, the kvcache stored in the kvcache management system is still (num_blocks, num_kv_heads, block_size, 2 * head_size)

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@tjtanaa we see an issue if we don't define the shape and stride order when the shuffle layout is enabled: the pool is then labeled (num_blocks, num_kv_heads, block_size, 2*head_size), where each tokens K is immediately followed by its own V, head_size elements apart. The cache write kernel still writes each blocks K in the shuffle layout because of shuffle layout flag enabled, which assumes K and V are kept apart. Looking into how is it working with shuffle layout enabled for asm pa kernel before this change.

@ukannika ukannika Aug 21, 2026

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@tjtanaa Enabled the shuffle layout flag and tested the Llama2 70B model using the asm_pa code path. I am seeing an accuracy issue, and the current state of this file is broken due to the layout changes introduced in this PR #44455. AITER assembly paged-attention kernels require independently contiguous K and V storage. This PR addresses the accuracy issue as well.
Here's the command to reproduce accuracy issue

export VLLM_ROCM_USE_AITER=1
export VLLM_ROCM_SHUFFLE_KV_CACHE_LAYOUT=1

vllm serve /model/llama2-70b-chat-hf/fp4_quantized_gptq \
  --dtype bfloat16 \
  --quantization quark \
  --tensor-parallel-size 1 \
  --max-model-len 2048 \
  --gpu-memory-utilization 0.94 \
  --attention-backend ROCM_AITER_FA \
  --kv-cache-dtype fp8 \
  --block-size 16 \
  --max-num-batched-tokens 32768 \
  --max-num-seqs 6400 \
  --enable-chunked-prefill \
  --async-scheduling \
  --host 0.0.0.0 \
  --port 8000

curl -s http://127.0.0.1:8000/v1/completions   -H "Content-Type: application/json"   -d '{
    "model": "/model/llama2-70b-chat-hf/fp4_quantized_gptq",
    "prompt": "The capital of France is",
    "max_tokens": 32,
    "temperature": 0
  }'```

@mergify

mergify Bot commented Aug 22, 2026

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This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @ukannika.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

@mergify mergify Bot added the needs-rebase label Aug 22, 2026
@ukannika
ukannika requested a review from tjtanaa August 22, 2026 23:03
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