CPU Servers

CPU Servers#

The document addresses how to set up the SGLang environment and run LLM inference on CPU servers. SGLang is enabled and optimized on the CPUs equipped with Intel® AMX® Instructions, which are 4th generation or newer Intel® Xeon® Scalable Processors.

Optimized Model List#

A list of popular LLMs are optimized and run efficiently on CPU, including the most notable open-source models like Llama series, Qwen series, and DeepSeek series like DeepSeek-R1 and DeepSeek-V3.1-Terminus.

Model Name

BF16

W8A8_INT8

FP8

DeepSeek-R1

meituan/DeepSeek-R1-Channel-INT8

deepseek-ai/DeepSeek-R1

DeepSeek-V3.1-Terminus

IntervitensInc/DeepSeek-V3.1-Terminus-Channel-int8

deepseek-ai/DeepSeek-V3.1-Terminus

Llama-3.2-3B

meta-llama/Llama-3.2-3B-Instruct

RedHatAI/Llama-3.2-3B-quantized.w8a8

Llama-3.1-8B

meta-llama/Llama-3.1-8B-Instruct

RedHatAI/Meta-Llama-3.1-8B-quantized.w8a8

QwQ-32B

RedHatAI/QwQ-32B-quantized.w8a8

DeepSeek-Distilled-Llama

RedHatAI/DeepSeek-R1-Distill-Llama-70B-quantized.w8a8

Qwen3-235B

Qwen/Qwen3-235B-A22B-FP8

Note: The model identifiers listed in the table above have been verified on 6th Gen Intel® Xeon® P-core platforms.

Installation#

Install Using Docker#

It is recommended to use Docker for setting up the SGLang environment. A Dockerfile is provided to facilitate the installation. Replace <secret> below with your HuggingFace access token.

# Clone the SGLang repository
git clone https://github.com/sgl-project/sglang.git
cd sglang/docker

# Build the docker image
docker build -t sglang-cpu:latest -f xeon.Dockerfile .

# Initiate a docker container
docker run \
    -it \
    --privileged \
    --ipc=host \
    --network=host \
    -v /dev/shm:/dev/shm \
    -v ~/.cache/huggingface:/root/.cache/huggingface \
    -p 30000:30000 \
    -e "HF_TOKEN=<secret>" \
    sglang-cpu:latest /bin/bash

Install From Source#

If you prefer to install SGLang in a bare metal environment, the setup process is as follows:

Please install the required packages and libraries beforehand if they are not already present on your system. You can refer to the Ubuntu-based installation commands in the Dockerfile for guidance.

  1. Install uv package manager, then create and activate a virtual environment:

# Taking '/opt' as the example uv env folder, feel free to change it as needed
cd /opt
curl -LsSf https://astral.sh/uv/install.sh | sh
source $HOME/.local/bin/env
uv venv --python 3.12
source .venv/bin/activate

  1. Create a config file to direct the installation channel (a.k.a. index-url) of torch related packages:

vim .venv/uv.toml

Press ‘a’ to enter insert mode of vim, paste the following content into the created file

[[index]]
name = "torch"
url = "https://download.pytorch.org/whl/cpu"

[[index]]
name = "torchvision"
url = "https://download.pytorch.org/whl/cpu"

[[index]]
name = "triton"
url = "https://download.pytorch.org/whl/cpu"

Save the file (in vim, press ‘esc’ to exit insert mode, then ‘:x+Enter’), and set it as the default uv config.

export UV_CONFIG_FILE=/opt/.venv/uv.toml

  1. Clone the sglang source code and build the packages

# Clone the SGLang code
git clone https://github.com/sgl-project/sglang.git
cd sglang
git checkout <YOUR-DESIRED-VERSION>

# Use dedicated toml file
cd python
cp pyproject_cpu.toml pyproject.toml
# Install SGLang dependent libs, and build SGLang main package
uv pip install --upgrade pip setuptools
uv pip install .
uv pip install torch==2.9.0 torchvision==0.24.0 triton==3.5.0 --force-reinstall

# Build the CPU backend kernels
cd ../sgl-kernel
cp pyproject_cpu.toml pyproject.toml
uv pip install .

  1. Set the required environment variables

export SGLANG_USE_CPU_ENGINE=1

# Set 'LD_LIBRARY_PATH' and 'LD_PRELOAD' to ensure the libs can be loaded by sglang processes
export LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu
export LD_PRELOAD=${LD_PRELOAD}:/opt/.venv/lib/libiomp5.so:${LD_LIBRARY_PATH}/libtcmalloc.so.4:${LD_LIBRARY_PATH}/libtbbmalloc.so.2

Notes:

  • Note that the environment variable SGLANG_USE_CPU_ENGINE=1 is required to enable the SGLang service with the CPU engine.

  • If you encounter code compilation issues during the sgl-kernel building process, please check your gcc and g++ versions and upgrade them if they are outdated. It is recommended to use gcc-13 and g++-13 as they have been verified in the official Docker container.

  • The system library path is typically located in one of the following directories: ~/.local/lib/, /usr/local/lib/, /usr/local/lib64/, /usr/lib/, /usr/lib64/ and /usr/lib/x86_64-linux-gnu/. In the above example commands, /usr/lib/x86_64-linux-gnu is used. Please adjust the path according to your server configuration.

  • It is recommended to add the following to your ~/.bashrc file to avoid setting these variables every time you open a new terminal:

    source .venv/bin/activate
export SGLANG_USE_CPU_ENGINE=1
export LD_LIBRARY_PATH=<YOUR-SYSTEM-LIBRARY-FOLDER>
export LD_PRELOAD=<YOUR-LIBS-PATHS>

Launch of the Serving Engine#

Example command to launch SGLang serving:

python -m sglang.launch_server   \
    --model <MODEL_ID_OR_PATH>   \
    --trust-remote-code          \
    --disable-overlap-schedule   \
    --device cpu                 \
    --host 0.0.0.0               \
    --tp 6

Notes:

  1. For running W8A8 quantized models, please add the flag --quantization w8a8_int8.

  2. The flag --tp 6 specifies that tensor parallelism will be applied using 6 ranks (TP6). The number of TP specified is how many TP ranks will be used during the execution. On a CPU platform, a TP rank means a sub-NUMA cluster (SNC). Usually we can get the SNC information (How many available) from the Operating System. Users can specify TP to be no more than the total available SNCs in current system.

    If the specified TP rank number differs from the total SNC count, the system will automatically utilize the first n SNCs. Note that n cannot exceed the total SNC number, doing so will result in an error.

    To specify the cores to be used, we need to explicitly set the environment variable SGLANG_CPU_OMP_THREADS_BIND. For example, if we want to run the SGLang service using the first 40 cores of each SNC on a Xeon® 6980P server, which has 43-43-42 cores on the 3 SNCs of a socket, we should set:

    export SGLANG_CPU_OMP_THREADS_BIND="0-39|43-82|86-125|128-167|171-210|214-253"

    Please beware that with SGLANG_CPU_OMP_THREADS_BIND set, the available memory amounts of the ranks may not be determined in prior. You may need to set proper --max-total-tokens to avoid the out-of-memory error.

  3. For optimizing decoding with torch.compile, please add the flag --enable-torch-compile. To specify the maximum batch size when using torch.compile, set the flag --torch-compile-max-bs. For example, --enable-torch-compile --torch-compile-max-bs 4 means using torch.compile and setting the maximum batch size to 4. Currently the maximum applicable batch size for optimizing with torch.compile is 16.

  4. A warmup step is automatically triggered when the service is started. The server is ready when you see the log The server is fired up and ready to roll!.

Benchmarking with Requests#

You can benchmark the performance via the bench_serving script. Run the command in another terminal. An example command would be:

python -m sglang.bench_serving   \
    --dataset-name random        \
    --random-input-len 1024      \
    --random-output-len 1024     \
    --num-prompts 1              \
    --request-rate inf           \
    --random-range-ratio 1.0

Detailed parameter descriptions are available via the command:

python -m sglang.bench_serving -h

Additionally, requests can be formatted using the OpenAI Completions API and sent via the command line (e.g., using curl) or through your own scripts.

Example Usage Commands#

Large Language Models can range from fewer than 1 billion to several hundred billion parameters. Dense models larger than 20B are expected to run on flagship 6th Gen Intel® Xeon® processors with dual sockets and a total of 6 sub-NUMA clusters. Dense models of approximately 10B parameters or fewer, or MoE (Mixture of Experts) models with fewer than 10B activated parameters, can run on more common 4th generation or newer Intel® Xeon® processors, or utilize a single socket of the flagship 6th Gen Intel® Xeon® processors.

Example: Running DeepSeek-V3.1-Terminus#

An example command to launch service of W8A8_INT8 DeepSeek-V3.1-Terminus on a Xeon® 6980P server:

python -m sglang.launch_server                                 \
    --model IntervitensInc/DeepSeek-V3.1-Terminus-Channel-int8 \
    --trust-remote-code                                        \
    --disable-overlap-schedule                                 \
    --device cpu                                               \
    --quantization w8a8_int8                                   \
    --host 0.0.0.0                                             \
    --enable-torch-compile                                     \
    --torch-compile-max-bs 4                                   \
    --tp 6

Similarly, an example command to launch service of FP8 DeepSeek-V3.1-Terminus would be:

python -m sglang.launch_server                     \
    --model deepseek-ai/DeepSeek-V3.1-Terminus     \
    --trust-remote-code                            \
    --disable-overlap-schedule                     \
    --device cpu                                   \
    --host 0.0.0.0                                 \
    --enable-torch-compile                         \
    --torch-compile-max-bs 4                       \
    --tp 6

Note: Please set --torch-compile-max-bs to the maximum desired batch size for your deployment, which can be up to 16. The value 4 in the examples is illustrative.

Example: Running Llama-3.2-3B#

An example command to launch service of Llama-3.2-3B with BF16 precision:

python -m sglang.launch_server                     \
    --model meta-llama/Llama-3.2-3B-Instruct       \
    --trust-remote-code                            \
    --disable-overlap-schedule                     \
    --device cpu                                   \
    --host 0.0.0.0                                 \
    --enable-torch-compile                         \
    --torch-compile-max-bs 16                      \
    --tp 2

The example command to launch service of W8A8_INT8 version of Llama-3.2-3B:

python -m sglang.launch_server                     \
    --model RedHatAI/Llama-3.2-3B-quantized.w8a8   \
    --trust-remote-code                            \
    --disable-overlap-schedule                     \
    --device cpu                                   \
    --quantization w8a8_int8                       \
    --host 0.0.0.0                                 \
    --enable-torch-compile                         \
    --torch-compile-max-bs 16                      \
    --tp 2

Note: The --torch-compile-max-bs and --tp settings are examples that should be adjusted for your setup. For instance, use --tp 3 to utilize 1 socket with 3 sub-NUMA clusters on an Intel® Xeon® 6980P server.

Once the server have been launched, you can test it using the bench_serving command or create your own commands or scripts following the benchmarking example.

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