torch-ccl
This repository holds PyTorch bindings maintained by Intel for the Intel® oneAPI Collective Communications Library (oneCCL).
Introduction
PyTorch is an open-source machine learning framework.
Intel® oneCCL (collective commnications library) is a library for efficient distributed deep learning training implementing such collectives like allreduce, allgather, alltoall. For more information on oneCCL, please refer to the oneCCL documentation and oneCCL specification.
torch-ccl module implements PyTorch C10D ProcessGroup API and can be dynamically loaded as external ProcessGroup and only works on Linux platform now.
Pytorch API Align
We recommend Anaconda as Python package management system. The following is the corresponding branchs (tags) of torch-ccl and supported Pytorch.
torch |
torch-ccl |
|---|---|
master |
master |
| v1.7.1 | ccl_torch1.7 |
| v1.6.0 | ccl_torch1.6 |
| v1.5-rc3 | beta09 |
The usage details can be found in the README of corresponding branch. The following part is about the usage of v1.7 tag. if you want to use other version of torch-ccl please checkout to that branch(tag). For pytorch-1.5.0-rc3, the #PR28068 and #PR32361 are need to dynamicall register external ProcessGroup and enable alltoall collective communication primitive. The patch file about these two PRs is in patches directory and you can use it directly.
Requirements
Python 3.6 or later and a C++14 compiler
pytorch-v1.7.1.
Installation
To install torch-ccl:
- clone the
torch-ccl.
git clone https://github.com/intel/torch-ccl.git && cd torch-ccl
git submodule sync
git submodule update --init --recursive- Install torch-ccl
python setup.py installUsage
example.py
import torch.nn.parallel
import torch.distributed as dist
import torch_ccl
...
os.environ['MASTER_ADDR'] = '127.0.0.1'
os.environ['MASTER_PORT'] = '29500'
os.environ['RANK'] = os.environ.get('PMI_RANK', -1)
os.environ['WORLD_SIZE'] = os.environ.get('PMI_SIZE', -1)
backend = 'ccl'
dist.init_process_group(backend, ...)
my_rank = dist.get_rank()
my_size = dist.get_world_size()
print("my rank = %d my size = %d" % (my_rank, my_size))
...
model = torch.nn.parallel.DistributedDataParallel(model, ...)
...(torch_ccl is installed along with the MPI toolset.)
$ source <torch_ccl_path>/env/setvars.sh
eg:
$ torch_ccl_path=$(python -c "import torch; import torch_ccl; import os; print(os.path.abspath(os.path.dirname(torch_ccl.__file__)))")
$ source $torch_ccl_path/env/setvars.sh
$ mpirun -n <N> -ppn <PPN> -f <hostfile> python example.py
Performance Debugging
For debugging performance of communication primitives PyTorch's Autograd profiler can be used to inspect time spent inside oneCCL calls.
Example:
profiling.py
import torch.nn.parallel
import torch.distributed as dist
import torch_ccl
import os
os.environ['MASTER_ADDR'] = '127.0.0.1'
os.environ['MASTER_PORT'] = '29500'
os.environ['RANK'] = os.environ.get('PMI_RANK', -1)
os.environ['WORLD_SIZE'] = os.environ.get('PMI_SIZE', -1)
backend = 'ccl'
dist.init_process_group(backend, ...)
my_rank = dist.get_rank()
my_size = dist.get_world_size()
print("my rank = %d my size = %d" % (my_rank, my_size))
x = torch.ones([2, 2])
y = torch.ones([4, 4])
with torch.autograd.profiler.profile(record_shapes=True) as prof:
for _ in range(10):
dist.all_reduce(x)
dist.all_reduce(y)
dist.barrier()
print(prof.key_averages(group_by_input_shape=True).table(sort_by="self_cpu_time_total"))$ mpirun -n 2 -l python profiling.py
[0] rank = 0, size = 2
[0] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[0] Name Self CPU total % Self CPU total CPU total % CPU total CPU time avg Number of Calls Input Shapes
[0] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[0] pg::allreduce 37.70% 61.935us 37.70% 61.935us 6.194us 10 [[2, 2]]
[0] pg::allreduce 23.40% 38.438us 23.40% 38.438us 3.844us 10 [[4, 4]]
[0] pg::wait::allreduce::sz:16 19.64% 32.258us 19.64% 32.258us 3.226us 10 []
[0] pg::wait::allreduce::sz:4 19.26% 31.634us 19.26% 31.634us 3.163us 10 []
[0] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[0] Self CPU time total: 164.265us
[0]
[1] rank = 1, size = 2
[1] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[1] Name Self CPU total % Self CPU total CPU total % CPU total CPU time avg Number of Calls Input Shapes
[1] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[1] pg::allreduce 50.27% 62.730us 50.27% 62.730us 6.273us 10 [[2, 2]]
[1] pg::allreduce 28.96% 36.133us 28.96% 36.133us 3.613us 10 [[4, 4]]
[1] pg::wait::allreduce::sz:4 13.83% 17.254us 13.83% 17.254us 1.725us 10 []
[1] pg::wait::allreduce::sz:16 6.95% 8.672us 6.95% 8.672us 0.867us 10 []
[1] ------------------------------ --------------- --------------- --------------- --------------- --------------- --------------- ---------------
[1] Self CPU time total: 124.789us
[1]