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ColossalAI/colossalai/legacy/context/process_group_initializer/initializer_sequence.py

108 lines
4.1 KiB

#!/usr/bin/env python
# -*- encoding: utf-8 -*-
import torch.distributed as dist
from colossalai.legacy.registry import DIST_GROUP_INITIALIZER
from ..parallel_mode import ParallelMode
from .initializer_tensor import Initializer_Tensor
from .process_group_initializer import ProcessGroupInitializer
@DIST_GROUP_INITIALIZER.register_module
class Initializer_Sequence_DP(ProcessGroupInitializer):
"""A ProcessGroupInitializer for sequence parallelism all-reduce.
In Sequence Parallelism, each GPU holds the full copy of model weights,
thus, gradient all-reduce occurs across all processes in the same pipeline stage
Args:
rank (int): The rank of current process
world_size (int): Size of whole communication world
config (Config): Running configuration
data_parallel_size (int): Size of data parallel
pipeline_parallel_size (int): Size of pipeline parallel
tensor_parallel_size (int): Size of tensor parallel
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.dp_size = self.world_size // self.pipeline_parallel_size
self.num_group = self.pipeline_parallel_size
def init_dist_group(self):
"""Initialize Sequence Parallel process groups used for gradient all-reduce.
Returns:
Tuple: A tuple (local_rank, group_world_size, process_group, ranks_in_group, mode).
"""
local_rank = None
ranks_in_group = None
process_group = None
cpu_group = None
group_world_size = None
mode = ParallelMode.SEQUENCE_DP
for i in range(self.num_group):
ranks = [i * self.dp_size + j for j in range(self.dp_size)]
group = dist.new_group(ranks)
group_cpu = dist.new_group(ranks, backend="gloo") if dist.get_backend() != "gloo" else group
if self.rank in ranks:
local_rank = ranks.index(self.rank)
group_world_size = len(ranks)
process_group = group
cpu_group = group_cpu
ranks_in_group = ranks
return local_rank, group_world_size, process_group, cpu_group, ranks_in_group, mode
@DIST_GROUP_INITIALIZER.register_module
class Initializer_Sequence(ProcessGroupInitializer):
"""A ProcessGroupInitializer for sequence parallelism.
Args:
rank (int): The rank of current process.
world_size (int): Size of whole communication world.
config (Config): Running configuration.
data_parallel_size (int): Size of data parallel.
pipeline_parallel_size (int): Size of pipeline parallel.
tensor_parallel_size (int): Size of tensor parallel.
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# reuse tensor parallel initializer code
self._sequence_initializer = Initializer_Tensor(*args, **kwargs)
self._sequence_dp_initializer = Initializer_Sequence_DP(*args, **kwargs)
def init_dist_group(self):
"""Initialize Sequence parallel process groups and assign local_ranks and groups to each gpu.
Sequence parallelism requires 2 process groups. The first is for model forward where several processes
exchange partial query, key and value embedding to compute self attention values. The second is for
all-reduce to synchronize the model parameters.
Returns:
List[Tuple (local_rank, group_world_size, process_group, ranks_in_group, mode)]:
A Sequence parallelism's information in list of tuples.
"""
parallel_setting = []
(
local_rank,
group_world_size,
process_group,
cpu_group,
ranks_in_group,
mode,
) = self._sequence_initializer.init_dist_group()
# change mode to sequence
mode = ParallelMode.SEQUENCE
parallel_setting.append((local_rank, group_world_size, process_group, cpu_group, ranks_in_group, mode))
parallel_setting.append(self._sequence_dp_initializer.init_dist_group())
return parallel_setting