[ROCm] [V1] [SpecDec] Enable Speculative Decoding on ROCm V1 Engine

[tjtanaa]

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

Purpose

Fix #21308

• after PR
• server command:

export VLLM_USE_V1=1
export VLLM_ROCM_USE_AITER=0
export VLLM_V1_USE_PREFILL_DECODE_ATTENTION=0
vllm serve meta-llama/Llama-3.1-8B-Instruct --trust-remote-code --swap-space 16 --disable-log-requests --tensor-parallel-size 1 --distributed-executor-backend mp --dtype float16 --quantization fp8 --no-enable-chunked-prefill --max-num-seqs 300  --max-num-batched-tokens 131072 --gpu-memory-utilization 0.8 --enforce-eager --speculative_config '{"method": "eagle3", "model": "yuhuili/EAGLE3-LLaMA3.1-Instruct-8B", "num_speculative_tokens": 2, "draft_tensor_parallel_size": 1, "dtype": "float16"}' --port 8001

• server log

INFO 07-27 13:23:18 [loggers.py:122] Engine 000: Avg prompt throughput: 7.9 tokens/s, Avg generation throughput: 1.8 tokens/s, Running: 0 reqs, Waiting: 0 reqs, GPU KV cache usage: 0.0%, Prefix cache hit rate: 0.0%
INFO 07-27 13:23:18 [metrics.py:87] SpecDecoding metrics: Draft acceptance rate: 56.2%, Mean acceptance length: 2.12, Accepted: 9 tokens, Drafted: 16 tokens, Per-position acceptance rate: 0.750, 0.375

Enable Speculative Decoding on ROCm V1 Engine:

• Eagle
• NGram

Test Plan

Enable and pass the unit tests:

• tests/v1/spec_decode/test_ngram.py
• tests/v1/spec_decode/test_max_len.py
• tests/v1/spec_decode/test_eagle.py
• tests/v1/e2e/test_spec_decode.py

Test Result

Pass status

• tests/v1/spec_decode/test_ngram.py
• tests/v1/spec_decode/test_max_len.py
• tests/v1/spec_decode/test_eagle.py
• tests/v1/e2e/test_spec_decode.py

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Code Review

This pull request enables speculative decoding on the ROCm V1 Engine, which is a great enhancement. The changes primarily involve updating test configurations to support different attention backends on ROCm and relaxing an assertion to allow for this.

I've found a critical issue in a test utility function where a try...except block is ineffective, potentially causing tests to run with incorrect configurations. I've also pointed out a misleading comment in the core logic that could cause confusion for future developers. Addressing these points will improve the correctness and maintainability of the code.

[SageMoore]

Just one minor suggestion. The rest looks good.

[mergify]

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

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

[mergify]

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

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

[DarkLight1337]

LGTM