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Model-Optimizer/examples/specdec_bench
Izzy PuttermanandKeval Morabia 5adb9ba0fc Add Spec dec Bench example (#474)
## What does this PR do?

**Type of change:** New feature <!-- Use one of the following: Bug fix,
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**Overview:** Specdec bench example

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```python
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---------

Signed-off-by: Izzy Putterman <iputterman@nvidia.com>
Signed-off-by: Keval Morabia <28916987+kevalmorabia97@users.noreply.github.com>
Co-authored-by: Keval Morabia <28916987+kevalmorabia97@users.noreply.github.com>
2025-11-06 21:21:26 +00:00
..
2025-11-06 21:21:26 +00:00
2025-11-06 21:21:26 +00:00

Speculative Decoding (SpecDec) Bench

Installation

This benchmark is meant to be a lightweight layer ontop of an existing vLLM/SGLang/TRTLLM installation. For example, no install is required if one is running in the following dockers: vllm/vllm-openai:v0.11.0 (vLLM), lmsysorg/sglang:v0.5.4.post2 (SGLang), or nvcr.io/nvidia/tensorrt-llm/release:1.2.0rc1 (TRT-LLM).

Next

cd examples/specdec_bench

Purpose

Collect relevant metrics on acceptance rate, timing, and outputs for Speculative Decoding methods. Acceptance rate refers to the number of tokens generated on every iteration. For a standard Autoregressive LLM, this number is just 1.

Getting Started

A basic example run script is provided which benchmarks MTBench (a standard 160 prompts spanning 8 categories). MTBench is available here

Running MTBench on GPT OSS + Eagle3

Download nvidia/gpt-oss-120b-Eagle3 to a local directory /path/to/eagle.

python3 run.py --model_dir openai/gpt-oss-120b --tokenizer openai/gpt-oss-120b --draft_model_dir /path/to/eagle --mtbench question.jsonl --tp_size 1 --ep_size 1 --draft_length 3 --output_length 4096 --num_requests 80 --engine TRTLLM --concurrency 1

Running Random ids on GPT OSS + Eagle3

Download nvidia/gpt-oss-120b-Eagle3 to a local directory /path/to/eagle.

python3 run.py --model_dir openai/gpt-oss-120b --tokenizer openai/gpt-oss-120b --draft_model_dir /path/to/eagle --random_isl 1024 --tp_size 1 --ep_size 1 --draft_length 3 --output_length 4096 --num_requests 40 --engine TRTLLM --concurrency 1

Notes

The goal of this benchmark is to provide an easy way to configure, run, and compare speculative implementations across frameworks in an apples-to-apples method. This benchmark sends request in a single-threaded fashion, so running large concurrency (>256) may result in python async scheduling delays and skew metrics. If larger concurrency is needed, it is recommended to fully deploy the model using vllm serve, python -m sglang.launch_server, or trtllm-serve (for vLLM, SGlang, or TRTLLM respectively) and use a more robust benchmarking client like NVIDIA AI Perf.