Unverified Commit 32aa2059 authored by Rafael Vasquez's avatar Rafael Vasquez Committed by GitHub
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[Docs] Convert rST to MyST (Markdown) (#11145)


Signed-off-by: default avatarRafael Vasquez <rafvasq21@gmail.com>
parent 94d545a1
(debugging)=
# Debugging Tips
This document outlines some debugging strategies you can consider. If you think you've discovered a bug, please [search existing issues](https://github.com/vllm-project/vllm/issues?q=is%3Aissue) first to see if it has already been reported. If not, please [file a new issue](https://github.com/vllm-project/vllm/issues/new/choose), providing as much relevant information as possible.
```{note}
Once you've debugged a problem, remember to turn off any debugging environment variables defined, or simply start a new shell to avoid being affected by lingering debugging settings. Otherwise, the system might be slow with debugging functionalities left activated.
```
## Hangs downloading a model
If the model isn't already downloaded to disk, vLLM will download it from the internet which can take time and depend on your internet connection.
It's recommended to download the model first using the [huggingface-cli](https://huggingface.co/docs/huggingface_hub/en/guides/cli) and passing the local path to the model to vLLM. This way, you can isolate the issue.
## Hangs loading a model from disk
If the model is large, it can take a long time to load it from disk. Pay attention to where you store the model. Some clusters have shared filesystems across nodes, e.g. a distributed filesystem or a network filesystem, which can be slow.
It'd be better to store the model in a local disk. Additionally, have a look at the CPU memory usage, when the model is too large it might take a lot of CPU memory, slowing down the operating system because it needs to frequently swap between disk and memory.
```{note}
To isolate the model downloading and loading issue, you can use the `--load-format dummy` argument to skip loading the model weights. This way, you can check if the model downloading and loading is the bottleneck.
```
## Model is too large
If the model is too large to fit in a single GPU, you might want to [consider tensor parallelism](https://docs.vllm.ai/en/latest/serving/distributed_serving.html#distributed-inference-and-serving) to split the model across multiple GPUs. In that case, every process will read the whole model and split it into chunks, which makes the disk reading time even longer (proportional to the size of tensor parallelism). You can convert the model checkpoint to a sharded checkpoint using [this example](https://docs.vllm.ai/en/latest/getting_started/examples/save_sharded_state.html) . The conversion process might take some time, but later you can load the sharded checkpoint much faster. The model loading time should remain constant regardless of the size of tensor parallelism.
## Enable more logging
If other strategies don't solve the problem, it's likely that the vLLM instance is stuck somewhere. You can use the following environment variables to help debug the issue:
- `export VLLM_LOGGING_LEVEL=DEBUG` to turn on more logging.
- `export CUDA_LAUNCH_BLOCKING=1` to identify which CUDA kernel is causing the problem.
- `export NCCL_DEBUG=TRACE` to turn on more logging for NCCL.
- `export VLLM_TRACE_FUNCTION=1` to record all function calls for inspection in the log files to tell which function crashes or hangs.
## Incorrect network setup
The vLLM instance cannot get the correct IP address if you have a complicated network config. You can find a log such as `DEBUG 06-10 21:32:17 parallel_state.py:88] world_size=8 rank=0 local_rank=0 distributed_init_method=tcp://xxx.xxx.xxx.xxx:54641 backend=nccl` and the IP address should be the correct one.
If it's not, override the IP address using the environment variable `export VLLM_HOST_IP=<your_ip_address>`.
You might also need to set `export NCCL_SOCKET_IFNAME=<your_network_interface>` and `export GLOO_SOCKET_IFNAME=<your_network_interface>` to specify the network interface for the IP address.
## Error near `self.graph.replay()`
If vLLM crashes and the error trace captures it somewhere around `self.graph.replay()` in `vllm/worker/model_runner.py`, it is a CUDA error inside CUDAGraph.
To identify the particular CUDA operation that causes the error, you can add `--enforce-eager` to the command line, or `enforce_eager=True` to the {class}`~vllm.LLM` class to disable the CUDAGraph optimization and isolate the exact CUDA operation that causes the error.
## Incorrect hardware/driver
If GPU/CPU communication cannot be established, you can use the following Python script and follow the instructions below to confirm whether the GPU/CPU communication is working correctly.
```python
# Test PyTorch NCCL
import torch
import torch.distributed as dist
dist.init_process_group(backend="nccl")
local_rank = dist.get_rank() % torch.cuda.device_count()
torch.cuda.set_device(local_rank)
data = torch.FloatTensor([1,] * 128).to("cuda")
dist.all_reduce(data, op=dist.ReduceOp.SUM)
torch.cuda.synchronize()
value = data.mean().item()
world_size = dist.get_world_size()
assert value == world_size, f"Expected {world_size}, got {value}"
print("PyTorch NCCL is successful!")
# Test PyTorch GLOO
gloo_group = dist.new_group(ranks=list(range(world_size)), backend="gloo")
cpu_data = torch.FloatTensor([1,] * 128)
dist.all_reduce(cpu_data, op=dist.ReduceOp.SUM, group=gloo_group)
value = cpu_data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("PyTorch GLOO is successful!")
if world_size <= 1:
exit()
# Test vLLM NCCL, with cuda graph
from vllm.distributed.device_communicators.pynccl import PyNcclCommunicator
pynccl = PyNcclCommunicator(group=gloo_group, device=local_rank)
# pynccl is enabled by default for 0.6.5+,
# but for 0.6.4 and below, we need to enable it manually.
# keep the code for backward compatibility when because people
# prefer to read the latest documentation.
pynccl.disabled = False
s = torch.cuda.Stream()
with torch.cuda.stream(s):
data.fill_(1)
pynccl.all_reduce(data, stream=s)
value = data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("vLLM NCCL is successful!")
g = torch.cuda.CUDAGraph()
with torch.cuda.graph(cuda_graph=g, stream=s):
pynccl.all_reduce(data, stream=torch.cuda.current_stream())
data.fill_(1)
g.replay()
torch.cuda.current_stream().synchronize()
value = data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("vLLM NCCL with cuda graph is successful!")
dist.destroy_process_group(gloo_group)
dist.destroy_process_group()
```
If you are testing with a single node, adjust `--nproc-per-node` to the number of GPUs you want to use:
```console
$ NCCL_DEBUG=TRACE torchrun --nproc-per-node=<number-of-GPUs> test.py
```
If you are testing with multi-nodes, adjust `--nproc-per-node` and `--nnodes` according to your setup and set `MASTER_ADDR` to the correct IP address of the master node, reachable from all nodes. Then, run:
```console
$ NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --rdzv_backend=c10d --rdzv_endpoint=$MASTER_ADDR test.py
```
If the script runs successfully, you should see the message `sanity check is successful!`.
If the test script hangs or crashes, usually it means the hardware/drivers are broken in some sense. You should try to contact your system administrator or hardware vendor for further assistance. As a common workaround, you can try to tune some NCCL environment variables, such as `export NCCL_P2P_DISABLE=1` to see if it helps. Please check [their documentation](https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/env.html) for more information. Please only use these environment variables as a temporary workaround, as they might affect the performance of the system. The best solution is still to fix the hardware/drivers so that the test script can run successfully.
```{note}
A multi-node environment is more complicated than a single-node one. If you see errors such as `torch.distributed.DistNetworkError`, it is likely that the network/DNS setup is incorrect. In that case, you can manually assign node rank and specify the IP via command line arguments:
- In the first node, run `NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --node-rank 0 --master_addr $MASTER_ADDR test.py`.
- In the second node, run `NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --node-rank 1 --master_addr $MASTER_ADDR test.py`.
Adjust `--nproc-per-node`, `--nnodes`, and `--node-rank` according to your setup, being sure to execute different commands (with different `--node-rank`) on different nodes.
```
## Python multiprocessing
### `RuntimeError` Exception
If you have seen a warning in your logs like this:
```console
WARNING 12-11 14:50:37 multiproc_worker_utils.py:281] CUDA was previously
initialized. We must use the `spawn` multiprocessing start method. Setting
VLLM_WORKER_MULTIPROC_METHOD to 'spawn'. See
https://docs.vllm.ai/en/latest/getting_started/debugging.html#python-multiprocessing
for more information.
```
or an error from Python that looks like this:
```console
RuntimeError:
An attempt has been made to start a new process before the
current process has finished its bootstrapping phase.
This probably means that you are not using fork to start your
child processes and you have forgotten to use the proper idiom
in the main module:
if __name__ == '__main__':
freeze_support()
...
The "freeze_support()" line can be omitted if the program
is not going to be frozen to produce an executable.
To fix this issue, refer to the "Safe importing of main module"
section in https://docs.python.org/3/library/multiprocessing.html
```
then you must update your Python code to guard usage of `vllm` behind a `if
__name__ == '__main__':` block. For example, instead of this:
```python
import vllm
llm = vllm.LLM(...)
```
try this instead:
```python
if __name__ == '__main__':
import vllm
llm = vllm.LLM(...)
```
## Known Issues
- In `v0.5.2`, `v0.5.3`, and `v0.5.3.post1`, there is a bug caused by [zmq](https://github.com/zeromq/pyzmq/issues/2000) , which can occasionally cause vLLM to hang depending on the machine configuration. The solution is to upgrade to the latest version of `vllm` to include the [fix](https://github.com/vllm-project/vllm/pull/6759).
- To circumvent a NCCL [bug](https://github.com/NVIDIA/nccl/issues/1234) , all vLLM processes will set an environment variable ``NCCL_CUMEM_ENABLE=0`` to disable NCCL's ``cuMem`` allocator. It does not affect performance but only gives memory benefits. When external processes want to set up a NCCL connection with vLLM's processes, they should also set this environment variable, otherwise, inconsistent environment setup will cause NCCL to hang or crash, as observed in the [RLHF integration](https://github.com/OpenRLHF/OpenRLHF/pull/604) and the [discussion](https://github.com/vllm-project/vllm/issues/5723#issuecomment-2554389656) .
.. _debugging:
===============
Debugging Tips
===============
This document outlines some debugging strategies you can consider. If you think you've discovered a bug, please `search existing issues <https://github.com/vllm-project/vllm/issues?q=is%3Aissue>`_ first to see if it has already been reported. If not, please `file a new issue <https://github.com/vllm-project/vllm/issues/new/choose>`_, providing as much relevant information as possible.
.. note::
Once you've debugged a problem, remember to turn off any debugging environment variables defined, or simply start a new shell to avoid being affected by lingering debugging settings. Otherwise, the system might be slow with debugging functionalities left activated.
Hangs downloading a model
----------------------------------------
If the model isn't already downloaded to disk, vLLM will download it from the internet which can take time and depend on your internet connection.
It's recommended to download the model first using the `huggingface-cli <https://huggingface.co/docs/huggingface_hub/en/guides/cli>`_ and passing the local path to the model to vLLM. This way, you can isolate the issue.
Hangs loading a model from disk
----------------------------------------
If the model is large, it can take a long time to load it from disk. Pay attention to where you store the model. Some clusters have shared filesystems across nodes, e.g. a distributed filesystem or a network filesystem, which can be slow.
It'd be better to store the model in a local disk. Additionally, have a look at the CPU memory usage, when the model is too large it might take a lot of CPU memory, slowing down the operating system because it needs to frequently swap between disk and memory.
.. note::
To isolate the model downloading and loading issue, you can use the ``--load-format dummy`` argument to skip loading the model weights. This way, you can check if the model downloading and loading is the bottleneck.
Model is too large
----------------------------------------
If the model is too large to fit in a single GPU, you might want to `consider tensor parallelism <https://docs.vllm.ai/en/latest/serving/distributed_serving.html#distributed-inference-and-serving>`_ to split the model across multiple GPUs. In that case, every process will read the whole model and split it into chunks, which makes the disk reading time even longer (proportional to the size of tensor parallelism). You can convert the model checkpoint to a sharded checkpoint using `this example <https://docs.vllm.ai/en/latest/getting_started/examples/save_sharded_state.html>`_ . The conversion process might take some time, but later you can load the sharded checkpoint much faster. The model loading time should remain constant regardless of the size of tensor parallelism.
Enable more logging
----------------------------------------
If other strategies don't solve the problem, it's likely that the vLLM instance is stuck somewhere. You can use the following environment variables to help debug the issue:
- ``export VLLM_LOGGING_LEVEL=DEBUG`` to turn on more logging.
- ``export CUDA_LAUNCH_BLOCKING=1`` to identify which CUDA kernel is causing the problem.
- ``export NCCL_DEBUG=TRACE`` to turn on more logging for NCCL.
- ``export VLLM_TRACE_FUNCTION=1`` to record all function calls for inspection in the log files to tell which function crashes or hangs.
Incorrect network setup
----------------------------------------
The vLLM instance cannot get the correct IP address if you have a complicated network config. You can find a log such as ``DEBUG 06-10 21:32:17 parallel_state.py:88] world_size=8 rank=0 local_rank=0 distributed_init_method=tcp://xxx.xxx.xxx.xxx:54641 backend=nccl`` and the IP address should be the correct one.
If it's not, override the IP address using the environment variable ``export VLLM_HOST_IP=<your_ip_address>``.
You might also need to set ``export NCCL_SOCKET_IFNAME=<your_network_interface>`` and ``export GLOO_SOCKET_IFNAME=<your_network_interface>`` to specify the network interface for the IP address.
Error near ``self.graph.replay()``
----------------------------------------
If vLLM crashes and the error trace captures it somewhere around ``self.graph.replay()`` in ``vllm/worker/model_runner.py``, it is a CUDA error inside CUDAGraph.
To identify the particular CUDA operation that causes the error, you can add ``--enforce-eager`` to the command line, or ``enforce_eager=True`` to the :class:`~vllm.LLM` class to disable the CUDAGraph optimization and isolate the exact CUDA operation that causes the error.
Incorrect hardware/driver
----------------------------------------
If GPU/CPU communication cannot be established, you can use the following Python script and follow the instructions below to confirm whether the GPU/CPU communication is working correctly.
.. code-block:: python
# Test PyTorch NCCL
import torch
import torch.distributed as dist
dist.init_process_group(backend="nccl")
local_rank = dist.get_rank() % torch.cuda.device_count()
torch.cuda.set_device(local_rank)
data = torch.FloatTensor([1,] * 128).to("cuda")
dist.all_reduce(data, op=dist.ReduceOp.SUM)
torch.cuda.synchronize()
value = data.mean().item()
world_size = dist.get_world_size()
assert value == world_size, f"Expected {world_size}, got {value}"
print("PyTorch NCCL is successful!")
# Test PyTorch GLOO
gloo_group = dist.new_group(ranks=list(range(world_size)), backend="gloo")
cpu_data = torch.FloatTensor([1,] * 128)
dist.all_reduce(cpu_data, op=dist.ReduceOp.SUM, group=gloo_group)
value = cpu_data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("PyTorch GLOO is successful!")
if world_size <= 1:
exit()
# Test vLLM NCCL, with cuda graph
from vllm.distributed.device_communicators.pynccl import PyNcclCommunicator
pynccl = PyNcclCommunicator(group=gloo_group, device=local_rank)
# pynccl is enabled by default for 0.6.5+,
# but for 0.6.4 and below, we need to enable it manually.
# keep the code for backward compatibility when because people
# prefer to read the latest documentation.
pynccl.disabled = False
s = torch.cuda.Stream()
with torch.cuda.stream(s):
data.fill_(1)
pynccl.all_reduce(data, stream=s)
value = data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("vLLM NCCL is successful!")
g = torch.cuda.CUDAGraph()
with torch.cuda.graph(cuda_graph=g, stream=s):
pynccl.all_reduce(data, stream=torch.cuda.current_stream())
data.fill_(1)
g.replay()
torch.cuda.current_stream().synchronize()
value = data.mean().item()
assert value == world_size, f"Expected {world_size}, got {value}"
print("vLLM NCCL with cuda graph is successful!")
dist.destroy_process_group(gloo_group)
dist.destroy_process_group()
If you are testing with a single node, adjust ``--nproc-per-node`` to the number of GPUs you want to use:
.. code-block:: console
$ NCCL_DEBUG=TRACE torchrun --nproc-per-node=<number-of-GPUs> test.py
If you are testing with multi-nodes, adjust ``--nproc-per-node`` and ``--nnodes`` according to your setup and set ``MASTER_ADDR`` to the correct IP address of the master node, reachable from all nodes. Then, run:
.. code-block:: console
$ NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --rdzv_backend=c10d --rdzv_endpoint=$MASTER_ADDR test.py
If the script runs successfully, you should see the message ``sanity check is successful!``.
If the test script hangs or crashes, usually it means the hardware/drivers are broken in some sense. You should try to contact your system administrator or hardware vendor for further assistance. As a common workaround, you can try to tune some NCCL environment variables, such as ``export NCCL_P2P_DISABLE=1`` to see if it helps. Please check `their documentation <https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/env.html>`__ for more information. Please only use these environment variables as a temporary workaround, as they might affect the performance of the system. The best solution is still to fix the hardware/drivers so that the test script can run successfully.
.. note::
A multi-node environment is more complicated than a single-node one. If you see errors such as ``torch.distributed.DistNetworkError``, it is likely that the network/DNS setup is incorrect. In that case, you can manually assign node rank and specify the IP via command line arguments:
- In the first node, run ``NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --node-rank 0 --master_addr $MASTER_ADDR test.py``.
- In the second node, run ``NCCL_DEBUG=TRACE torchrun --nnodes 2 --nproc-per-node=2 --node-rank 1 --master_addr $MASTER_ADDR test.py``.
Adjust ``--nproc-per-node``, ``--nnodes``, and ``--node-rank`` according to your setup, being sure to execute different commands (with different ``--node-rank``) on different nodes.
Python multiprocessing
----------------------
`RuntimeError` Exception
^^^^^^^^^^^^^^^^^^^^^^^^
If you have seen a warning in your logs like this:
.. code-block:: console
WARNING 12-11 14:50:37 multiproc_worker_utils.py:281] CUDA was previously
initialized. We must use the `spawn` multiprocessing start method. Setting
VLLM_WORKER_MULTIPROC_METHOD to 'spawn'. See
https://docs.vllm.ai/en/latest/getting_started/debugging.html#python-multiprocessing
for more information.
or an error from Python that looks like this:
.. code-block:: console
RuntimeError:
An attempt has been made to start a new process before the
current process has finished its bootstrapping phase.
This probably means that you are not using fork to start your
child processes and you have forgotten to use the proper idiom
in the main module:
if __name__ == '__main__':
freeze_support()
...
The "freeze_support()" line can be omitted if the program
is not going to be frozen to produce an executable.
To fix this issue, refer to the "Safe importing of main module"
section in https://docs.python.org/3/library/multiprocessing.html
then you must update your Python code to guard usage of ``vllm`` behind a ``if
__name__ == '__main__':`` block. For example, instead of this:
.. code-block:: python
import vllm
llm = vllm.LLM(...)
try this instead:
.. code-block:: python
if __name__ == '__main__':
import vllm
llm = vllm.LLM(...)
Known Issues
----------------------------------------
- In ``v0.5.2``, ``v0.5.3``, and ``v0.5.3.post1``, there is a bug caused by `zmq <https://github.com/zeromq/pyzmq/issues/2000>`_ , which can occasionally cause vLLM to hang depending on the machine configuration. The solution is to upgrade to the latest version of ``vllm`` to include the `fix <https://github.com/vllm-project/vllm/pull/6759>`_.
- To circumvent a NCCL `bug <https://github.com/NVIDIA/nccl/issues/1234>`__ , all vLLM processes will set an environment variable ``NCCL_CUMEM_ENABLE=0`` to disable NCCL's ``cuMem`` allocator. It does not affect performance but only gives memory benefits. When external processes want to set up a NCCL connection with vLLM's processes, they should also set this environment variable, otherwise, inconsistent environment setup will cause NCCL to hang or crash, as observed in `the RLHF integration <https://github.com/OpenRLHF/OpenRLHF/pull/604>`__ and the `discussion <https://github.com/vllm-project/vllm/issues/5723#issuecomment-2554389656>`__ .
# Examples
```{toctree}
:maxdepth: 1
:caption: Scripts
%EXAMPLE_DOCS%
```
\ No newline at end of file
Examples
=================================
.. toctree::
:maxdepth: 1
:caption: Scripts
%EXAMPLE_DOCS%
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(installation)=
# Installation
vLLM is a Python library that also contains pre-compiled C++ and CUDA (12.1) binaries.
## Requirements
- OS: Linux
- Python: 3.9 -- 3.12
- GPU: compute capability 7.0 or higher (e.g., V100, T4, RTX20xx, A100, L4, H100, etc.)
## Install released versions
You can install vLLM using pip:
```console
$ # (Recommended) Create a new conda environment.
$ conda create -n myenv python=3.12 -y
$ conda activate myenv
$ # Install vLLM with CUDA 12.1.
$ pip install vllm
```
```{note}
Although we recommend using `conda` to create and manage Python environments, it is highly recommended to use `pip` to install vLLM. This is because `pip` can install `torch` with separate library packages like `NCCL`, while `conda` installs `torch` with statically linked `NCCL`. This can cause issues when vLLM tries to use `NCCL`. See [this issue](https://github.com/vllm-project/vllm/issues/8420) for more details.
```
````{note}
As of now, vLLM's binaries are compiled with CUDA 12.1 and public PyTorch release versions by default.
We also provide vLLM binaries compiled with CUDA 11.8 and public PyTorch release versions:
```console
$ # Install vLLM with CUDA 11.8.
$ export VLLM_VERSION=0.6.1.post1
$ export PYTHON_VERSION=310
$ pip install https://github.com/vllm-project/vllm/releases/download/v${VLLM_VERSION}/vllm-${VLLM_VERSION}+cu118-cp${PYTHON_VERSION}-cp${PYTHON_VERSION}-manylinux1_x86_64.whl --extra-index-url https://download.pytorch.org/whl/cu118
```
In order to be performant, vLLM has to compile many cuda kernels. The compilation unfortunately introduces binary incompatibility with other CUDA versions and PyTorch versions, even for the same PyTorch version with different building configurations.
Therefore, it is recommended to install vLLM with a **fresh new** conda environment. If either you have a different CUDA version or you want to use an existing PyTorch installation, you need to build vLLM from source. See below for instructions.
````
(install-the-latest-code)=
## Install the latest code
LLM inference is a fast-evolving field, and the latest code may contain bug fixes, performance improvements, and new features that are not released yet. To allow users to try the latest code without waiting for the next release, vLLM provides wheels for Linux running on a x86 platform with CUDA 12 for every commit since `v0.5.3`. You can download and install it with the following command:
```console
$ pip install https://vllm-wheels.s3.us-west-2.amazonaws.com/nightly/vllm-1.0.0.dev-cp38-abi3-manylinux1_x86_64.whl
```
If you want to access the wheels for previous commits, you can specify the commit hash in the URL:
```console
$ export VLLM_COMMIT=33f460b17a54acb3b6cc0b03f4a17876cff5eafd # use full commit hash from the main branch
$ pip install https://vllm-wheels.s3.us-west-2.amazonaws.com/${VLLM_COMMIT}/vllm-1.0.0.dev-cp38-abi3-manylinux1_x86_64.whl
```
Note that the wheels are built with Python 3.8 ABI (see [PEP 425](https://peps.python.org/pep-0425/) for more details about ABI), so **they are compatible with Python 3.8 and later**. The version string in the wheel file name (`1.0.0.dev`) is just a placeholder to have a unified URL for the wheels. The actual versions of wheels are contained in the wheel metadata. Although we don't support Python 3.8 any more (because PyTorch 2.5 dropped support for Python 3.8), the wheels are still built with Python 3.8 ABI to keep the same wheel name as before.
Another way to access the latest code is to use the docker images:
```console
$ export VLLM_COMMIT=33f460b17a54acb3b6cc0b03f4a17876cff5eafd # use full commit hash from the main branch
$ docker pull public.ecr.aws/q9t5s3a7/vllm-ci-postmerge-repo:${VLLM_COMMIT}
```
These docker images are used for CI and testing only, and they are not intended for production use. They will be expired after several days.
The latest code can contain bugs and may not be stable. Please use it with caution.
(build-from-source)=
## Build from source
(python-only-build)=
### Python-only build (without compilation)
If you only need to change Python code, you can build and install vLLM without compilation. Using `pip`'s [`--editable` flag](https://pip.pypa.io/en/stable/topics/local-project-installs/#editable-installs), changes you make to the code will be reflected when you run vLLM:
```console
$ git clone https://github.com/vllm-project/vllm.git
$ cd vllm
$ VLLM_USE_PRECOMPILED=1 pip install --editable .
```
This will download the latest nightly wheel and use the compiled libraries from there in the install.
The `VLLM_PRECOMPILED_WHEEL_LOCATION` environment variable can be used instead of `VLLM_USE_PRECOMPILED` to specify a custom path or URL to the wheel file. For example, to use the [0.6.1.post1 PyPi wheel](https://pypi.org/project/vllm/#files):
```console
$ export VLLM_PRECOMPILED_WHEEL_LOCATION=https://files.pythonhosted.org/packages/4a/4c/ee65ba33467a4c0de350ce29fbae39b9d0e7fcd887cc756fa993654d1228/vllm-0.6.3.post1-cp38-abi3-manylinux1_x86_64.whl
$ pip install --editable .
```
You can find more information about vLLM's wheels [above](#install-the-latest-code).
```{note}
There is a possibility that your source code may have a different commit ID compared to the latest vLLM wheel, which could potentially lead to unknown errors.
It is recommended to use the same commit ID for the source code as the vLLM wheel you have installed. Please refer to [the section above](#install-the-latest-code) for instructions on how to install a specified wheel.
```
### Full build (with compilation)
If you want to modify C++ or CUDA code, you'll need to build vLLM from source. This can take several minutes:
```console
$ git clone https://github.com/vllm-project/vllm.git
$ cd vllm
$ pip install -e .
```
```{tip}
Building from source requires a lot of compilation. If you are building from source repeatedly, it's more efficient to cache the compilation results.
For example, you can install [ccache](https://github.com/ccache/ccache) using `conda install ccache` or `apt install ccache` .
As long as `which ccache` command can find the `ccache` binary, it will be used automatically by the build system. After the first build, subsequent builds will be much faster.
[sccache](https://github.com/mozilla/sccache) works similarly to `ccache`, but has the capability to utilize caching in remote storage environments.
The following environment variables can be set to configure the vLLM `sccache` remote: `SCCACHE_BUCKET=vllm-build-sccache SCCACHE_REGION=us-west-2 SCCACHE_S3_NO_CREDENTIALS=1`. We also recommend setting `SCCACHE_IDLE_TIMEOUT=0`.
```
#### Use an existing PyTorch installation
There are scenarios where the PyTorch dependency cannot be easily installed via pip, e.g.:
- Building vLLM with PyTorch nightly or a custom PyTorch build.
- Building vLLM with aarch64 and CUDA (GH200), where the PyTorch wheels are not available on PyPI. Currently, only the PyTorch nightly has wheels for aarch64 with CUDA. You can run `pip3 install --pre torch torchvision torchaudio --index-url https://download.pytorch.org/whl/nightly/cu124` to [install PyTorch nightly](https://pytorch.org/get-started/locally/), and then build vLLM on top of it.
To build vLLM using an existing PyTorch installation:
```console
$ git clone https://github.com/vllm-project/vllm.git
$ cd vllm
$ python use_existing_torch.py
$ pip install -r requirements-build.txt
$ pip install -e . --no-build-isolation
```
#### Use the local cutlass for compilation
Currently, before starting the build process, vLLM fetches cutlass code from GitHub. However, there may be scenarios where you want to use a local version of cutlass instead.
To achieve this, you can set the environment variable VLLM_CUTLASS_SRC_DIR to point to your local cutlass directory.
```console
$ git clone https://github.com/vllm-project/vllm.git
$ cd vllm
$ VLLM_CUTLASS_SRC_DIR=/path/to/cutlass pip install -e .
```
#### Troubleshooting
To avoid your system being overloaded, you can limit the number of compilation jobs
to be run simultaneously, via the environment variable `MAX_JOBS`. For example:
```console
$ export MAX_JOBS=6
$ pip install -e .
```
This is especially useful when you are building on less powerful machines. For example, when you use WSL it only [assigns 50% of the total memory by default](https://learn.microsoft.com/en-us/windows/wsl/wsl-config#main-wsl-settings), so using `export MAX_JOBS=1` can avoid compiling multiple files simultaneously and running out of memory.
A side effect is a much slower build process.
Additionally, if you have trouble building vLLM, we recommend using the NVIDIA PyTorch Docker image.
```console
$ # Use `--ipc=host` to make sure the shared memory is large enough.
$ docker run --gpus all -it --rm --ipc=host nvcr.io/nvidia/pytorch:23.10-py3
```
If you don't want to use docker, it is recommended to have a full installation of CUDA Toolkit. You can download and install it from [the official website](https://developer.nvidia.com/cuda-toolkit-archive). After installation, set the environment variable `CUDA_HOME` to the installation path of CUDA Toolkit, and make sure that the `nvcc` compiler is in your `PATH`, e.g.:
```console
$ export CUDA_HOME=/usr/local/cuda
$ export PATH="${CUDA_HOME}/bin:$PATH"
```
Here is a sanity check to verify that the CUDA Toolkit is correctly installed:
```console
$ nvcc --version # verify that nvcc is in your PATH
$ ${CUDA_HOME}/bin/nvcc --version # verify that nvcc is in your CUDA_HOME
```
### Unsupported OS build
vLLM can fully run only on Linux but for development purposes, you can still build it on other systems (for example, macOS), allowing for imports and a more convenient development environment. The binaries will not be compiled and won't work on non-Linux systems.
Simply disable the `VLLM_TARGET_DEVICE` environment variable before installing:
```console
$ export VLLM_TARGET_DEVICE=empty
$ pip install -e .
```
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(installation-neuron)=
# Installation with Neuron
vLLM 0.3.3 onwards supports model inferencing and serving on AWS Trainium/Inferentia with Neuron SDK with continuous batching.
Paged Attention and Chunked Prefill are currently in development and will be available soon.
Data types currently supported in Neuron SDK are FP16 and BF16.
## Requirements
- OS: Linux
- Python: 3.9 -- 3.11
- Accelerator: NeuronCore_v2 (in trn1/inf2 instances)
- Pytorch 2.0.1/2.1.1
- AWS Neuron SDK 2.16/2.17 (Verified on python 3.8)
Installation steps:
- [Build from source](#build-from-source-neuron)
- [Step 0. Launch Trn1/Inf2 instances](#launch-instances)
- [Step 1. Install drivers and tools](#install-drivers)
- [Step 2. Install transformers-neuronx and its dependencies](#install-tnx)
- [Step 3. Install vLLM from source](#install-vllm)
(build-from-source-neuron)=
```{note}
The currently supported version of Pytorch for Neuron installs `triton` version `2.1.0`. This is incompatible with vLLM >= 0.5.3. You may see an error `cannot import name 'default_dump_dir...`. To work around this, run a `pip install --upgrade triton==3.0.0` after installing the vLLM wheel.
```
## Build from source
Following instructions are applicable to Neuron SDK 2.16 and beyond.
(launch-instances)=
### Step 0. Launch Trn1/Inf2 instances
Here are the steps to launch trn1/inf2 instances, in order to install [PyTorch Neuron ("torch-neuronx") Setup on Ubuntu 22.04 LTS](https://awsdocs-neuron.readthedocs-hosted.com/en/latest/general/setup/neuron-setup/pytorch/neuronx/ubuntu/torch-neuronx-ubuntu22.html).
- Please follow the instructions at [launch an Amazon EC2 Instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EC2_GetStarted.html#ec2-launch-instance) to launch an instance. When choosing the instance type at the EC2 console, please make sure to select the correct instance type.
- To get more information about instances sizes and pricing see: [Trn1 web page](https://aws.amazon.com/ec2/instance-types/trn1/), [Inf2 web page](https://aws.amazon.com/ec2/instance-types/inf2/)
- Select Ubuntu Server 22.04 TLS AMI
- When launching a Trn1/Inf2, please adjust your primary EBS volume size to a minimum of 512GB.
- After launching the instance, follow the instructions in [Connect to your instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AccessingInstancesLinux.html) to connect to the instance
(install-drivers)=
### Step 1. Install drivers and tools
The installation of drivers and tools wouldn't be necessary, if [Deep Learning AMI Neuron](https://docs.aws.amazon.com/dlami/latest/devguide/appendix-ami-release-notes.html) is installed. In case the drivers and tools are not installed on the operating system, follow the steps below:
```console
# Configure Linux for Neuron repository updates
. /etc/os-release
sudo tee /etc/apt/sources.list.d/neuron.list > /dev/null <<EOF
deb https://apt.repos.neuron.amazonaws.com ${VERSION_CODENAME} main
EOF
wget -qO - https://apt.repos.neuron.amazonaws.com/GPG-PUB-KEY-AMAZON-AWS-NEURON.PUB | sudo apt-key add -
# Update OS packages
sudo apt-get update -y
# Install OS headers
sudo apt-get install linux-headers-$(uname -r) -y
# Install git
sudo apt-get install git -y
# install Neuron Driver
sudo apt-get install aws-neuronx-dkms=2.* -y
# Install Neuron Runtime
sudo apt-get install aws-neuronx-collectives=2.* -y
sudo apt-get install aws-neuronx-runtime-lib=2.* -y
# Install Neuron Tools
sudo apt-get install aws-neuronx-tools=2.* -y
# Add PATH
export PATH=/opt/aws/neuron/bin:$PATH
```
(install-tnx)=
### Step 2. Install transformers-neuronx and its dependencies
[transformers-neuronx](https://github.com/aws-neuron/transformers-neuronx) will be the backend to support inference on trn1/inf2 instances.
Follow the steps below to install transformer-neuronx package and its dependencies.
```console
# Install Python venv
sudo apt-get install -y python3.10-venv g++
# Create Python venv
python3.10 -m venv aws_neuron_venv_pytorch
# Activate Python venv
source aws_neuron_venv_pytorch/bin/activate
# Install Jupyter notebook kernel
pip install ipykernel
python3.10 -m ipykernel install --user --name aws_neuron_venv_pytorch --display-name "Python (torch-neuronx)"
pip install jupyter notebook
pip install environment_kernels
# Set pip repository pointing to the Neuron repository
python -m pip config set global.extra-index-url https://pip.repos.neuron.amazonaws.com
# Install wget, awscli
python -m pip install wget
python -m pip install awscli
# Update Neuron Compiler and Framework
python -m pip install --upgrade neuronx-cc==2.* --pre torch-neuronx==2.1.* torchvision transformers-neuronx
```
(install-vllm)=
### Step 3. Install vLLM from source
Once neuronx-cc and transformers-neuronx packages are installed, we will be able to install vllm as follows:
```console
$ git clone https://github.com/vllm-project/vllm.git
$ cd vllm
$ pip install -U -r requirements-neuron.txt
$ VLLM_TARGET_DEVICE="neuron" pip install .
```
If neuron packages are detected correctly in the installation process, `vllm-0.3.0+neuron212` will be installed.
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