ColossalAI/colossalai/communication/collective.py

262 lines
11 KiB
Python

#!/usr/bin/env python
# -*- encoding: utf-8 -*-
import torch
import torch.distributed as dist
from torch.distributed import ReduceOp
from torch import Tensor
from colossalai.context import ParallelMode
from colossalai.core import global_context as gpc
def all_gather(tensor: Tensor,
dim: int,
parallel_mode: ParallelMode,
on_cpu: bool = False,
async_op: bool = False) -> Tensor:
r"""Gathers all tensors from the parallel group and concatenates them in a
specific dimension.
Note:
The parallel_mode should be concluded in ``ParallelMode``. More details about ``ParallelMode`` could be found
in `parallel_mode <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/context/parallel_mode.py>`_.
Args:
tensor (:class:`torch.Tensor`): Tensor to be gathered.
dim (int): The dimension concatenating in.
parallel_mode (:class:`colossalai.context.ParallelMode`): Parallel group mode used in this communication.
on_cpu (bool, optional): Whether to communicate with Gloo backend.
async_op (bool, optional): Whether operations are asynchronous.
Returns:
Union[tuple(:class:`torch.Tensor`, work handle), :class:`torch.Tensor`]: The result of all-together only,
if async_op is set to False. A tuple of output of all-gather and Async work handle, if async_op is set to True.
"""
depth = gpc.get_world_size(parallel_mode)
if depth == 1:
out = tensor
work = None
else:
shape = list(tensor.shape)
shape[0], shape[dim] = shape[dim], shape[0]
shape[0] *= depth
out = torch.empty(shape, dtype=tensor.dtype, device=tensor.device)
temp = list(torch.chunk(out, depth, dim=0))
group = gpc.get_cpu_group(parallel_mode) if on_cpu else gpc.get_group(parallel_mode)
work = dist.all_gather(tensor_list=temp,
tensor=tensor.transpose(0, dim).contiguous(),
group=group,
async_op=async_op)
out = torch.transpose(out, 0, dim)
if async_op:
return out, work
else:
return out
def reduce_scatter(tensor: Tensor,
dim: int,
parallel_mode: ParallelMode,
op: ReduceOp = ReduceOp.SUM,
on_cpu: bool = False,
async_op: bool = False) -> Tensor:
r"""Reduces all tensors then scatters it in a specific dimension to all
members in the parallel group.
Note:
The parallel_mode should be concluded in ``ParallelMode``. More details about ``ParallelMode`` could be found
in `parallel_mode <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/context/parallel_mode.py>`_.
Args:
tensor (:class:`torch.Tensor`): Tensor to be reduce_scattered.
dim (int): The dimension concatenating in.
parallel_mode (:class:`colossalai.context.ParallelMode`): Parallel group mode used in this communication.
op (torch.distributed.ReduceOp, optional): The type of reduce operation,
should be included in [SUM, AVG, PRODUCT, MIN, MAX, BAND, BOR, BXOR].
More details about ReduceOp please refer to
`ReduceOp <https://pytorch.org/docs/stable/distributed.html#torch.distributed.ReduceOp>`_.
on_cpu (bool, optional): Whether to communicate with Gloo backend.
async_op (bool, optional): Whether operations are asynchronous.
Returns:
Union[tuple(:class:`torch.Tensor`, work handle), :class:`torch.Tensor`]: The result of reduce_scatter only,
if async_op is set to False. A tuple of output of all-gather and Async work handle, if async_op is set to True.
"""
depth = gpc.get_world_size(parallel_mode)
if depth == 1:
out = tensor
work = None
else:
temp = list(map(lambda x: x.contiguous(), torch.chunk(tensor, depth, dim=dim)))
out = torch.empty(temp[0].shape, dtype=tensor.dtype, device=tensor.device)
group = gpc.get_cpu_group(parallel_mode) if on_cpu else gpc.get_group(parallel_mode)
work = dist.reduce_scatter(output=out, input_list=temp, op=op, group=group, async_op=async_op)
if async_op:
return out, work
else:
return out
def all_reduce(tensor: Tensor,
parallel_mode: ParallelMode,
op: ReduceOp = ReduceOp.SUM,
on_cpu: bool = False,
async_op: bool = False) -> Tensor:
r"""Reduces the tensor data across whole parallel group in such a way that all get the final result.
Note:
The parallel_mode should be concluded in ``ParallelMode``. More details about ``ParallelMode`` could be found
in `parallel_mode <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/context/parallel_mode.py>`_.
Args:
tensor (:class:`torch.Tensor`): Tensor to be all-reduced.
parallel_mode (:class:`colossalai.context.ParallelMode`): Parallel group mode used in this communication.
op (torch.distributed.ReduceOp, optional): The type of reduce operation,
should be included in [SUM, AVG, PRODUCT, MIN, MAX, BAND, BOR, BXOR].
More details about ReduceOp please refer to
`ReduceOp <https://pytorch.org/docs/stable/distributed.html#torch.distributed.ReduceOp>`_.
on_cpu (bool, optional): Whether to communicate with Gloo backend.
async_op (bool, optional): Whether operations are asynchronous.
Returns:
Union[tuple(:class:`torch.Tensor`, work handle), :class:`torch.Tensor`]: The result of all-gather only,
if async_op is set to False. A tuple of output of all-gather and Async work handle, if async_op is set to True.
"""
depth = gpc.get_world_size(parallel_mode)
if depth == 1:
out = tensor
work = None
else:
out = tensor.contiguous()
group = gpc.get_cpu_group(parallel_mode) if on_cpu else gpc.get_group(parallel_mode)
work = dist.all_reduce(out, op=op, group=group, async_op=async_op)
if async_op:
return out, work
else:
return out
def broadcast(tensor: Tensor, src: int, parallel_mode: ParallelMode, on_cpu: bool = False, async_op: bool = False):
r"""Broadcast tensors to whole parallel group. Tensor must have the same
number of elements in all processes participating in the collective.
Note:
The parallel_mode should be concluded in ``ParallelMode``. More details about ``ParallelMode`` could be found
in `parallel_mode <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/context/parallel_mode.py>`_.
Args:
tensor (:class:`torch.Tensor`): Tensor to be broadcast.
src (int): Source rank.
parallel_mode (:class:`colossalai.context.ParallelMode`): Parallel group mode used in this communication.
on_cpu (bool, optional): Whether to communicate with Gloo backend.
async_op (bool, optional): Whether operations are asynchronous.
Returns:
Union[tuple(:class:`torch.Tensor`, work handle), :class:`torch.Tensor`]: The tensor need to be broadcast only,
if async_op is set to False. A tuple of output of all-gather and Async work handle, if async_op is set to True.
"""
depth = gpc.get_world_size(parallel_mode)
if depth == 1:
out = tensor
work = None
else:
out = tensor.contiguous()
group = gpc.get_cpu_group(parallel_mode) if on_cpu else gpc.get_group(parallel_mode)
work = dist.broadcast(out, src=src, group=group, async_op=async_op)
if async_op:
return out, work
else:
return out
def reduce(tensor: Tensor,
dst: int,
parallel_mode: ParallelMode,
op: ReduceOp = ReduceOp.SUM,
on_cpu: bool = False,
async_op: bool = False):
r"""Reduce tensors across whole parallel group. Only the process with
rank ``dst`` is going to receive the final result.
Note:
The parallel_mode should be concluded in ``ParallelMode``. More details about ``ParallelMode`` could be found
in `parallel_mode <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/context/parallel_mode.py>`_.
Args:
tensor (:class:`torch.Tensor`): Tensor to be reduced.
dst (int): Destination rank.
parallel_mode (:class:`colossalai.context.ParallelMode`): Parallel group mode used in this communication.
on_cpu (bool, optional): Whether to communicate with Gloo backend.
async_op (bool, optional): Whether operations are asynchronous.
Returns:
Union[tuple(:class:`torch.Tensor`, work handle), :class:`torch.Tensor`]: The result of reduce only,
if async_op is set to False. A tuple of output of all-gather and Async work handle, if async_op is set to True.
"""
depth = gpc.get_world_size(parallel_mode)
if depth == 1:
out = tensor
work = None
else:
out = tensor.contiguous()
group = gpc.get_cpu_group(parallel_mode) if on_cpu else gpc.get_group(parallel_mode)
work = dist.reduce(out, dst=dst, op=op, group=group, async_op=async_op)
if async_op:
return out, work
else:
return out
def scatter_object_list(scatter_object_output_list, scatter_object_input_list, src=0, group=None):
r"""Modified from `torch.distributed.scatter_object_list <https://pytorch.org/docs/stable/_modules/torch/distributed/distributed_c10d.html#scatter_object_list>` to fix issues
"""
if dist._rank_not_in_group(group):
return
if (not isinstance(scatter_object_output_list, list) or len(scatter_object_output_list) < 1):
raise RuntimeError("Expected argument scatter_object_output_list to be a list of size at least 1.")
# set tensor device to cuda if backend is nccl
device = torch.cuda.current_device() if dist.get_backend(group) == 'nccl' else torch.device("cpu")
my_rank = dist.get_rank() # use global rank
if my_rank == src:
tensor_list, tensor_sizes = zip(
*[dist.distributed_c10d._object_to_tensor(obj) for obj in scatter_object_input_list])
tensor_list = list(map(lambda x: x.to(device), tensor_list))
tensor_sizes = list(map(lambda x: x.to(device), tensor_sizes))
# Src rank broadcasts the maximum tensor size. This is because all ranks are
# expected to call into scatter() with equal-sized tensors.
if my_rank == src:
max_tensor_size = max(tensor_sizes)
for tensor in tensor_list:
tensor.resize_(max_tensor_size)
else:
max_tensor_size = torch.tensor([0], dtype=torch.long).to(device)
dist.broadcast(max_tensor_size, src=src, group=group)
# Scatter actual serialized objects
output_tensor = torch.empty(max_tensor_size.item(), dtype=torch.uint8).to(device)
dist.scatter(
output_tensor,
scatter_list=None if my_rank != src else tensor_list,
src=src,
group=group,
)
# Scatter per-object sizes to trim tensors when deserializing back to object
obj_tensor_size = torch.tensor([0], dtype=torch.long).to(device)
dist.scatter(
obj_tensor_size,
scatter_list=None if my_rank != src else tensor_sizes,
src=src,
group=group,
)
output_tensor, obj_tensor_size = output_tensor.cpu(), obj_tensor_size.cpu()
# Deserialize back to object
scatter_object_output_list[0] = dist.distributed_c10d._tensor_to_object(output_tensor, obj_tensor_size)