[ROCm][AMD] GLM5.2/5.3 Performance Optimization on gfx950 / MI355X

This feature page tracks the peformance optimization of [amd/GLM-5.2-MXFP4](https://huggingface.co/amd/GLM-5.2-MXFP4) / [amd/GLM-5.3-Quark-MXFP4-AttnFP8](https://huggingface.co/amd/GLM-5.3-Quark-MXFP4-AttnFP8) on gf950/MI355X
The following list of PRs lands as stacked PRs on vllm-project/vllm main.

CC:
@tjtanaa, @jhartika-amd, @maeehart, @nholmber

Nvidia equivalence
- [In review] Index Share feature (1% E2E TTFT improvement) - vllm-project/vllm#51309
- [In review] Remove aten fill functor in prefill MQA logits (1% E2E TTFT improvement) - vllm-project/vllm#51314

AITER kernel optimization:
- [In review] use AITER kernel for `cp_gather_indexer_k_quant_cache` and `indexer_k_quant_and_cache` and `top_k_per_row_decode` instead of triton - vllm-project/vllm#46172
- [In review] Sparse indexer kernel fusion for K normalization, Q/K RoPE, FP8 quantization, and K-cache write - `indexer_qk_rope_quant_and_cache` (1% E2E throughput improvement) - vllm-project/vllm#51315
- [In review] MLA fused kernel for rope, query concat, KV concat, fp8 cache write -` fused_qk_rope_concat_and_cache_mla` - vllm-project/vllm#47757
- [In review] Replace ATen gemm with tuned AITER gemm `aiter.tuned_gemm.tgemm.mm` (3% E2E throughput improvement) - vllm-project/vllm#50535
- [closed] fMoE tuning for gfx950 (5% E2E throughput improvement) - ROCm/aiter#4629
- [open in aiter] Dispatch to FlyDSL MQA logits in prefill `flydsl_fp8_mqa_logits` (1.5% E2E throughput improvement)

Additional optimization
- [ready] FP8 dtype hoist - vllm-project/vllm#53792

AITER dependencies that need to be merged
- FlyDSL paged MQA logits in decode - ROCm/aiter#4221
- FlyDSL MQA logits in prefill - ROCm/aiter#4538
- FlyDSL topk - ROCm/aiter#4355

Planned tasks
- [open in aiter] Dispatch to FlyDSL paged MQA logits in decode `flydsl_fp8_paged_mqa_logits` (1 week ETA, expected 1.5% E2E throughput improvement)
- MTP enablement:
- support next_n > 2
- AITER kernel support
- FlyDSL kernel for quick all reduce (INT4) - ROCm/aiter#4970​

This issue is a tracking page rather than a single change. Start by reviewing the listed vLLM and ROCm/aiter PRs and planned tasks, then identify one unclaimed optimization with a defined benchmark target. Done means the selected task and its required dependency are implemented, merged, and show the stated performance improvement.

Written by the indexing model from the issue text.