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130 lines
4.5 KiB
130 lines
4.5 KiB
from typing import Tuple
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import torch
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import torch.distributed as dist
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from colossalai.context.parallel_mode import ParallelMode
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from colossalai.context.singleton_meta import SingletonMeta
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from colossalai.tensor import ProcessGroup
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def _check_sanity():
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from colossalai.core import global_context as gpc
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if gpc.tensor_parallel_size > 1 or gpc.pipeline_parallel_size > 1:
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raise NotImplementedError("Moe is not compatible with tensor or "
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"pipeline parallel at present.")
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class MoeParallelInfo:
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"""Moe parallelism information, storing parallel sizes and groups.
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"""
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def __init__(self, ep_size: int, dp_size: int):
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_check_sanity()
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self.ep_size = ep_size
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self.dp_size = dp_size
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self.pg = ProcessGroup(tp_degree=ep_size, dp_degree=dp_size)
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self.ep_group = self.pg.tp_process_group()
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self.dp_group = self.pg.dp_process_group()
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class MoeContext(metaclass=SingletonMeta):
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"""MoE parallel context manager. This class manages different
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parallel groups in MoE context and MoE loss in training.
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"""
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def __init__(self):
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self.world_size = 1
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# Users may want to set maximum expert parallel size smaller than the world size
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# since very low bandwidth across nodes may constrain the performance of MoE
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# When we have a maximum expert parallel size, we have a minimum data parallel size naturally
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self.max_ep_size = 1
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self.min_dp_size = 1
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self.aux_loss = None
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self.use_kernel_optim = True
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self.has_setup = False
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self._parallel_info_dict = dict()
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@property
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def parallel_info_dict(self):
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return self._parallel_info_dict
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@property
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def is_initialized(self):
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return self.has_setup
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def setup(self, seed: int, use_kernel_optim: bool = True):
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assert not self.is_initialized, "MoE distributed context shouldn't be set up again"
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_check_sanity()
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assert torch.cuda.is_available(), "MoE requires to enable CUDA first"
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self.world_size = dist.get_world_size()
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from colossalai.core import global_context as gpc
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self.max_ep_size = gpc.config.get('max_ep_size', self.world_size)
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assert self.world_size % self.max_ep_size == 0, \
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"Maximum epxert parallel size must be a factor of the number of GPUs"
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self.min_dp_size = self.world_size // self.max_ep_size
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# Enabling kernel optimization may raise error in some cases
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# Users can close kernel optimization manually
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self.use_kernel_optim = use_kernel_optim
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from .random import moe_set_seed
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moe_set_seed(seed)
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self.has_setup = True
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def get_info(self, num_experts: int) -> Tuple[int, MoeParallelInfo]:
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"""Calculate the Data Parallel Group and Expert Parallel Group.
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Parameters
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----------
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num_experts : int
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The number experts
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Returns
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-------
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int, MoeParallelInfo
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number of local experts, the MoeParallelInfo of the current ep_size
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"""
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gt_flag = num_experts % self.max_ep_size == 0 # check whether num_experts is greater
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lt_flag = self.max_ep_size % num_experts == 0 # check whether num_experts is less
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assert gt_flag or lt_flag, "Automatic experts placement dose not not support expert number" \
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" is not a multiple of ep size or vice versa."
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# If the number of experts is greater than maximum expert parallel size. a.k.a ep_size,
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# there are multiple experts in each GPU and each GPU has different experts
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# So it's data parallel size is 1
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# Otherwise, there is only one expert in each GPU
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# The data parallel size should be calculated
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dp_size = 1 if gt_flag else self.max_ep_size // num_experts
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ep_size = self.max_ep_size // dp_size
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# Calculate the number of experts for each GPU
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num_local_experts = 1 if lt_flag else num_experts // self.max_ep_size
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# Don't forget to multiply minimum data parallel size
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dp_size *= self.min_dp_size
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if not (ep_size in self.parallel_info_dict):
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self.parallel_info_dict[ep_size] = MoeParallelInfo(ep_size, dp_size)
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return num_local_experts, self.parallel_info_dict[ep_size]
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def set_kernel_not_use(self):
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self.use_kernel_optim = False
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def reset_loss(self):
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self.aux_loss = 0
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def add_loss(self, loss):
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self.aux_loss += loss
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def get_loss(self):
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return self.aux_loss
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MOE_CONTEXT = MoeContext()
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