vllm/tests/distributed/test_pynccl.py
2024-03-27 00:33:26 -07:00

91 lines
3.0 KiB
Python

import multiprocessing
import os
import pytest
import torch
from vllm.model_executor.parallel_utils.pynccl import (NCCLCommunicator,
ncclGetUniqueId)
def distributed_run(fn, world_size):
number_of_processes = world_size
processes = []
for i in range(number_of_processes):
env = os.environ.copy()
env['RANK'] = str(i)
env['WORLD_SIZE'] = str(number_of_processes)
env['MASTER_ADDR'] = 'localhost'
env['MASTER_PORT'] = '12345'
p = multiprocessing.Process(target=fn, args=(env, ))
processes.append(p)
p.start()
for p in processes:
p.join()
def update_env(fn):
# `multiprocessing.Process` cannot accept environment variables directly
# so we need to pass the environment variables as arguments
# and update the environment variables in the function
def wrapper(env):
import os
os.environ.update(env)
fn()
return wrapper
@update_env
def worker_fn():
comm = NCCLCommunicator()
tensor = torch.ones(16, 1024, 1024, dtype=torch.float32).cuda(comm.rank)
comm.all_reduce(tensor)
result = tensor.mean().cpu().item()
assert result == comm.world_size
@pytest.mark.skipif(torch.cuda.device_count() < 2,
reason="Need at least 2 GPUs to run the test.")
def test_pynccl():
distributed_run(worker_fn, 2)
@update_env
def worker_fn_with_cudagraph():
with torch.no_grad():
graph = torch.cuda.CUDAGraph()
comm = NCCLCommunicator()
# run something in the default stream to initialize torch engine
a = torch.ones((4, 4), device=f'cuda:{comm.rank}')
torch.cuda.synchronize()
with torch.cuda.graph(graph, stream=comm.stream):
# operation during the graph capture is recorded but not executed
# see https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#creating-a-graph-using-stream-capture # noqa
comm.all_reduce(a)
comm.stream.synchronize()
assert a.mean().cpu().item() == comm.world_size**0
graph.replay()
comm.stream.synchronize()
assert a.mean().cpu().item() == comm.world_size**1
@pytest.mark.skipif(torch.cuda.device_count() < 2,
reason="Need at least 2 GPUs to run the test.")
def test_pynccl_with_cudagraph():
distributed_run(worker_fn_with_cudagraph, 2)
def test_ncclGetUniqueId():
unique_id = ncclGetUniqueId()
# `list(unique_id.internal)` is something like this:
# [34, -16, 23, 83, 109, -19, 59, 95, 2, 0, -86, 55, 10, -128, 0, 29, 0,
# 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
# 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
# 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
# 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
# 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
# as long as the function doesn't raise an exception, we're good
assert unique_id is not None