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ColossalAI/colossalai/cluster/device_mesh_manager.py

118 lines
4.1 KiB

from dataclasses import dataclass
from typing import Dict, List, Tuple, Union
import torch
import torch.distributed as dist
from colossalai.device.alpha_beta_profiler import AlphaBetaProfiler
from colossalai.device.device_mesh import DeviceMesh
@dataclass
class DeviceMeshInfo:
'''
This class is used to store the information used to initialize the device mesh.
Args:
physical_ids (List[int]): The physical ids of the current booster. For example, if we have the last 4 GPUs on a 8-devices cluster, then the physical ids should be [4, 5, 6, 7].
mesh_shapes (List[Union[torch.Size, List[int], Tuple[int]]]): The shape of the mesh. For example, if we have 4 GPUs and we want to use 2D mesh with mesh shape [2, 2], then the mesh shape should be [2, 2].
'''
physical_ids: List[int]
mesh_shape: Union[torch.Size, List[int], Tuple[int]] = None
def __post_init__(self):
if self.mesh_shape is not None:
world_size = len(self.physical_ids)
mesh_shape_numel = torch.Size(self.mesh_shape).numel()
assert world_size == mesh_shape_numel, f'the numel of mesh_shape should be equal to world size, but got {world_size} != {mesh_shape_numel}'
def initialize_device_mesh(device_mesh_info: DeviceMeshInfo):
'''
This method is used to initialize the device mesh.
Args:
device_mesh_info (DeviceMeshInfo): The information used to initialize device mesh.
'''
# parse the device mesh info
physical_devices = device_mesh_info.physical_ids
physical_mesh = torch.tensor(physical_devices)
logical_mesh_shape = device_mesh_info.mesh_shape
if logical_mesh_shape is None:
ab_profiler = AlphaBetaProfiler(physical_devices)
# search for the best logical mesh shape
logical_mesh_id = ab_profiler.search_best_logical_mesh()
logical_mesh_id = torch.Tensor(logical_mesh_id).to(torch.int)
else:
logical_mesh_id = physical_mesh.reshape(logical_mesh_shape)
device_mesh = DeviceMesh(physical_mesh_id=physical_mesh, logical_mesh_id=logical_mesh_id, init_process_group=True)
return device_mesh
class DeviceMeshManager:
"""
Device mesh manager is responsible for creating and managing device meshes.
"""
def __init__(self):
self.device_mesh_store: Dict[str, DeviceMesh] = dict()
def create_device_mesh(self, name, device_mesh_info: DeviceMeshInfo) -> DeviceMesh:
"""
Create a device mesh and store it in the manager.
Args:
name (str): name of the device mesh
device_mesh_info (DeviceMeshInfo): the information used to initialize the device mesh
"""
if name not in self.device_mesh_store:
device_mesh = initialize_device_mesh(device_mesh_info)
self.device_mesh_store[name] = device_mesh
return device_mesh
else:
raise ValueError(f'Device mesh {name} already exists.')
def get(self, name: str) -> DeviceMesh:
"""
Get a device mesh by name.
Args:
name (str): name of the device mesh
Returns:
DeviceMesh: the device mesh
"""
if name in self.device_mesh_store:
return self.device_mesh_store[name]
else:
raise ValueError(f'Device mesh {name} does not exist.')
def destroy(self, name: str) -> None:
"""
Destroy a device mesh by name.
Args:
name (str): name of the device mesh
"""
if name in self.device_mesh_store:
for pgs in self.device_mesh_store[name].process_groups_dict.values():
for pg in pgs:
dist.destroy_process_group(pg)
del self.device_mesh_store[name]
else:
raise ValueError(f'Device mesh {name} does not exist.')
def destroy_all(self):
"""
Destroy all device meshes.
"""
for name in self.device_mesh_store:
for pgs in self.device_mesh_store[name].process_groups_dict.values():
for pg in pgs:
dist.destroy_process_group(pg)
self.device_mesh_store.clear()