Vidur: LLM Inference Simulator

Vidur is a high-fidelity LLM inference simulator, designed to aid capacity planning and deployment configuration optimization. Please refer to our MLSys'24 paper for more details.
We have a live demo that captures the capabilities of the system.

Difference in 95th percentile Request E2E Normalized time showing fidelity of Vidur's execution time predictions across four models and three dynamic workload traces, using request load at 85% of the maximum serving capacity for each scenario. Capacity per dollar for different deployment configurations vs TTFT-P90 (left) and TBT-P99 (middle) for LLaMA2-70B.

Setup

Using mamba

To run the simulator, create a mamba environment with the given dependency file.

mamba env create -p ./env -f ./environment.yml
mamba env update -f environment-dev.yml

Using venv

1. Ensure that you have Python 3.10 installed on your system. Refer https://www.bitecode.dev/p/installing-python-the-bare-minimum
2. cd into the repository root
3. Create a virtual environment using venv module using python3.10 -m venv .venv
4. Activate the virtual environment using source .venv/bin/activate
5. Install the dependencies using python -m pip install -r requirements.txt
6. Run deactivate to deactivate the virtual environment

Using conda (Least recommended)

To run the simulator, create a conda environment with the given dependency file.

conda env create -p ./env -f ./environment.yml
conda env update -f environment-dev.yml

Setting up wandb (Optional)

First, setup your account on https://<your-org>.wandb.io/ or public wandb, obtain the api key and then run the following command,

wandb login --host https://<your-org>.wandb.io

To opt out of wandb, pick any one of the following methods:

1. export WANDB_MODE=disabled in your shell or add this in ~/.zshrc or ~/.bashrc. Remember to reload using source ~/.zshrc.
2. Set wandb_project and wandb_group as "" in vidur/config/default.yml. Also, remove these CLI params from the shell command with which the simulator is invoked.

Running the simulator

To run the simulator, execute the following command from the repository root,

python -m vidur.main

or a big example with all the parameters,

python -m vidur.main  \
--replica_device a100 \
--replica_model_name meta-llama/Llama-2-7b-hf  \
--cluster_num_replicas 1 \
--replica_num_tensor_parallel_workers 1 \
--replica_num_pipeline_stages 1 \
--request_generator_provider synthetic \
--synthetic_request_generator_length_provider trace \
--synthetic_request_generator_interval_provider static \
--request_generator_max_tokens 4096 \
--trace_request_length_generator_trace_file ./data/processed_traces/arxiv_summarization_stats_llama2_tokenizer_filtered_v2.csv \
--synthetic_request_generator_num_requests 128  \
--request_generator_provider synthetic \
--synthetic_request_generator_length_provider trace \
--synthetic_request_generator_interval_provider static \
--request_generator_max_tokens 4096 \
--trace_request_length_generator_trace_file ./data/processed_traces/arxiv_summarization_stats_llama2_tokenizer_filtered_v2.csv \
--synthetic_request_generator_num_requests 128  \
--replica_scheduler_provider vllm  \
--replica_scheduler_batch_size_cap 256  \
--vllm_scheduler_max_tokens_in_batch 4096

The simulator supports a plethora of parameters for the simulation description which can be found here.

The metrics will be logged to wandb directly and a copy will be stored in the simulator_output directory along with the chrome trace. A description of all the logged metrics can be found here.

Supported Models

• Pipeline parallelism is supported for all models. The PP dimension should divide the number of layers in the model.
• In DGX nodes, there are 8 GPUs, fully connected via NVLink. So TP1, TP2, TP4 and TP8 are supported.
• In 4x pairwise NVLink nodes, there are 4 GPUs, so TP1, TP2 and TP4 are supported. TP4 here is less performant than TP4 in DGX nodes because (GPU1, GPU2) are connected via NVLink and (GPU3, GPU4) are connected via NVLink. but between these layers, the interconnect is slower.
• You can use any combination of TP and PP. For example, you can run LLaMA2-70B on TP2-PP2 on a 4xA100 80GB Pairwise NVLink Node.
• Instructions on adding a new model to existing or new SKUs can be found here.

Chrome Trace

Vidur exports chrome traces of each simulation. The trace can be found in the simulator_output directory. The trace can be opened by navigating to chrome://tracing/ or edge://tracing/ and loading the trace.

Formatting Code

To run the code formatters execute the following command,

make format

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

Trademarks

This project may contain trademarks or logos for projects, products, or services. Authorized use of Microsoft trademarks or logos is subject to and must follow Microsoft's Trademark & Brand Guidelines. Use of Microsoft trademarks or logos in modified versions of this project must not cause confusion or imply Microsoft sponsorship. Any use of third-party trademarks or logos are subject to those third-party's policies.