/usr/local/lib64/python3.6/site-packages/torch/distributed/algorithms/model_averaging
Edit: /usr/local/lib64/python3.6/site-packages/torch/distributed/algorithms/model_averaging/utils.py (1392B)
# flake8: noqa C101
import itertools
from typing import Iterator
import torch
import torch.distributed as dist
def average_parameters(
params: Iterator[torch.nn.Parameter], process_group: dist.ProcessGroup
):
"""
Averages all the given parameters.
For allreduce efficiency, all the parameters are flattened into a contiguous buffer.
Thus, it requires extra memory of the same size as the given parameters.
"""
group_to_use = process_group if process_group is not None else dist.group.WORLD
# Do not update any parameter if not in the process group.
if dist._rank_not_in_group(group_to_use):
return
params_it1, params_it2 = itertools.tee(params)
# If the input parameters have different data types,
# packing these parameters will trigger an implicit type up-casting.
# The original parameter data types will be restored during the subsequent unpacking.
flat_params = torch.cat([p.data.view(-1) for p in params_it1])
flat_params /= dist.get_world_size(group_to_use)
# Make sure the allreduce will not conflict with any other ongoing process group.
if torch.cuda.is_available():
torch.cuda.synchronize()
dist.all_reduce(flat_params, group=group_to_use)
offset = 0
for p in params_it2:
p.data = flat_params[offset : offset + p.numel()].view_as(p).type_as(p)
offset += p.numel()