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333 lines
16 KiB
333 lines
16 KiB
import torch
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import torch.distributed as dist
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from enum import Enum
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from torch.optim import Optimizer
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from colossalai.nn.parallel.data_parallel import ZeroDDP
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from typing import Dict
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from colossalai.amp.naive_amp.grad_scaler import DynamicGradScaler
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from colossalai.logging import get_dist_logger
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from colossalai.nn.optimizer import ColossalaiOptimizer
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from colossalai.utils import get_current_device, disposable
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from colossalai.utils.common import _compute_grad_lp, compute_grad_norm, _clip_grad_norm
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from collections import defaultdict, abc as container_abcs
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from copy import deepcopy
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from itertools import chain
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from torch._six import inf
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class OptimState(Enum):
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SCALED = 0
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UNSCALED = 1
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class ZeroOptimizer(ColossalaiOptimizer):
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"""A wrapper for optimizer. ``ZeroDDP`` and ``ZeroOptimizer`` implement Zero Redundancy Optimizer (ZeRO state-3).
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Note:
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You must use ``ZeroDDP`` with ``ZeroOptimizer``.
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Note:
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Make sure you set ``placement_policy`` of ``GeminiManager`` to `"auto"`,
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if you set ``gpu_margin_mem_ratio > 0``.
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Args:
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optim (Optimizer): An Optimizer instance.
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module (ZeroDDP): A ``ZeroDDP`` instance.
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gpu_margin_mem_ratio (float, optional): The ratio of GPU remaining memory (after the first forward-backward)
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which will be used when using hybrid CPU optimizer.
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This argument is meaningless when `placement_policy` of `GeminiManager` is not "auto".
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Defaults to 0.0.
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initial_scale (float, optional): Initial scale used by DynamicGradScaler. Defaults to 2**32.
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min_scale (float, optional): Min scale used by DynamicGradScaler. Defaults to 1.
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growth_factor (float, optional): growth_factor used by DynamicGradScaler. Defaults to 2.
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backoff_factor (float, optional): backoff_factor used by DynamicGradScaler. Defaults to 0.5.
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growth_interval (float, optional): growth_interval used by DynamicGradScaler. Defaults to 1000.
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hysteresis (float, optional): hysteresis used by DynamicGradScaler. Defaults to 2.
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max_scale (int, optional): max_scale used by DynamicGradScaler. Defaults to 2**32.
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"""
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def __init__(self,
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optim: Optimizer,
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module: ZeroDDP,
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gpu_margin_mem_ratio: float = 0.0,
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initial_scale: float = 2**32,
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min_scale: float = 1,
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growth_factor: float = 2,
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backoff_factor: float = 0.5,
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growth_interval: int = 1000,
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hysteresis: int = 2,
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max_scale: float = 2**32):
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super().__init__(optim)
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assert isinstance(module, ZeroDDP)
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self.module = module
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self.gemini_manager = module.gemini_manager
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self.chunk_manager = self.gemini_manager.chunk_manager
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self.optim_state = OptimState.UNSCALED
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self.fp16_param_to_fp32_param: Dict[torch.Tensor, torch.Tensor] = {}
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for p, fp32_p in zip(module.parameters(), module.fp32_params):
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self.fp16_param_to_fp32_param[p] = fp32_p
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# Grad scaler
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self.grad_scaler = DynamicGradScaler(initial_scale=initial_scale,
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min_scale=min_scale,
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growth_factor=growth_factor,
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backoff_factor=backoff_factor,
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growth_interval=growth_interval,
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hysteresis=hysteresis,
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max_scale=max_scale)
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self._found_overflow: torch.Tensor = torch.zeros(1, dtype=torch.int64, device=torch.cuda.current_device())
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self._logger = get_dist_logger()
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self.gpu_margin_mem_ratio: float = float(gpu_margin_mem_ratio)
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assert 0.0 <= self.gpu_margin_mem_ratio <= 1.0, f'gpu_margin_mem_ratio must >=0.0 and <=1.0'
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# Only move fp32 shards from CPU to GPU when user allows and inner optimizer is valid
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# Inner optimizer must support optimizing hybrid (CPU and CUDA) tensors,
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# and it must set `num_fp32_shards_per_param` correctly
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self._should_move_fp32_params_h2d: bool = self.gemini_manager.is_cuda_margin_mem_avail and self.gpu_margin_mem_ratio > 0.0 and getattr(
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optim, 'num_fp32_shards_per_param', 0) >= 2
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if self.gpu_margin_mem_ratio > 0.0 and not self.gemini_manager.is_cuda_margin_mem_avail:
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self._logger.warning(f'gpu_margin_mem_ratio is meaningless when placement_policy is not "auto"', ranks=[0])
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self._register_states = disposable(self._register_states_)
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def _update_params_ptr(self):
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for group in self.optim.param_groups:
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for p in group['params']:
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if not self.module.chunk_manager.get_chunk(p).is_empty:
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p.data = self.fp16_param_to_fp32_param[p]
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else:
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assert p.grad is None
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def _update_fp16_params(self):
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self.module.chunk_manager.copy_chunk_group('fp16_param', 'fp32_param')
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def _check_overflow(self):
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# clear previous overflow record
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self._found_overflow.fill_(self.module.overflow_counter)
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# all-reduce across global group
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dist.all_reduce(self._found_overflow)
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return self._found_overflow.item() > 0
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def _unscale_grads(self):
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assert self.optim_state == OptimState.SCALED
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for group in self.optim.param_groups:
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for p in group['params']:
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if p.grad is not None:
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p.grad.data.div_(self.loss_scale)
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self.optim_state = OptimState.UNSCALED
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@property
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def loss_scale(self):
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return self.grad_scaler.scale.item()
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def zero_grad(self, *args, **kwargs):
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self.module.overflow_counter = 0
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return self.optim.zero_grad(set_to_none=True)
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def step(self, *args, **kwargs):
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self._maybe_move_fp32_params()
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# unscale grads if scaled
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if self.optim_state == OptimState.SCALED:
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self._unscale_grads()
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found_inf = self._check_overflow()
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self.grad_scaler.update(found_inf)
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if found_inf:
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self._logger.info(f'Found overflow. Skip step')
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self.zero_grad()
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self._update_fp16_params()
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return
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self._update_params_ptr()
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ret = self.optim.step(*args, **kwargs)
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self._register_states()
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self.zero_grad()
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self._update_fp16_params()
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return ret
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def compute_grad_norm(self, norm_type: float = 2.0) -> float:
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norm_type = float(norm_type)
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if not self.chunk_manager.enable_distributed_storage:
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return compute_grad_norm(self.module.parameters(), norm_type)
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non_distributed_params = []
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distributed_params = []
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for p in self.module.parameters():
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if getattr(p, '_ddp_to_ignore', False):
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non_distributed_params.append(p)
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else:
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distributed_params.append(p)
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non_distributed_norm = _compute_grad_lp(non_distributed_params, norm_type)
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distributed_norm_tensor = torch.tensor([_compute_grad_lp(distributed_params, norm_type)],
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device=get_current_device())
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if norm_type == inf:
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dist.all_reduce(distributed_norm_tensor,
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op=dist.ReduceOp.MAX,
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group=self.chunk_manager.process_group.dp_process_group())
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total_norm = max(non_distributed_norm, distributed_norm_tensor.item())
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else:
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dist.all_reduce(distributed_norm_tensor, group=self.chunk_manager.process_group.dp_process_group())
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total_norm = non_distributed_norm + distributed_norm_tensor.item()
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total_norm = total_norm**(1 / norm_type)
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return total_norm
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def clip_grad_norm(self, model: torch.nn.Module, max_norm: float, norm_type: float = 2.0):
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if self.optim_state == OptimState.SCALED:
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self._unscale_grads()
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total_norm = self.compute_grad_norm(norm_type)
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_clip_grad_norm(self.module.parameters(), max_norm, total_norm)
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return total_norm
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def backward(self, loss: torch.Tensor):
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loss = self.loss_scale * loss
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self.optim_state = OptimState.SCALED
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self.module.backward(loss)
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def backward_by_grad(self, tensor: torch.Tensor, grad: torch.Tensor):
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# This function is called except the last stage of pipeline parallel
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# It receives the scaled grad from the previous rank
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# No need to scale the grad again
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# Need to unscale when optimizing
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self.optim_state = OptimState.SCALED
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self.module.backward_by_grad(tensor, grad)
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def _maybe_move_fp32_params(self):
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if self._should_move_fp32_params_h2d:
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self._should_move_fp32_params_h2d = False
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available_cuda_margin_mem = self.gemini_manager.cuda_margin_mem * self.gpu_margin_mem_ratio
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fp32_params_available_cuda_margin_mem = available_cuda_margin_mem / self.optim.num_fp32_shards_per_param
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fp32_params_used_cuda_margin_mem = 0
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for fp16_param_chunk, fp32_param_chunk in zip(self.chunk_manager.chunk_groups['fp16_param'],
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self.chunk_manager.chunk_groups['fp32_param']):
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if fp32_param_chunk.is_empty:
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continue
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if fp32_params_used_cuda_margin_mem + fp32_param_chunk.mem < fp32_params_available_cuda_margin_mem:
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self.chunk_manager.move_chunk(fp32_param_chunk, get_current_device())
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# stores grad now
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self.chunk_manager.move_chunk(fp16_param_chunk, get_current_device())
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self.module._set_chunk_grad_device(fp16_param_chunk, get_current_device())
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fp32_params_used_cuda_margin_mem += fp32_param_chunk.mem
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for p in fp16_param_chunk.get_tensors():
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state = self.optim.state[p]
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for k, v in state.items():
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if isinstance(v, torch.Tensor):
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state[k] = v.to(get_current_device())
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self.module._setup_grads_ptr()
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def _register_states_(self):
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for group in self.optim.param_groups:
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for p in group['params']:
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state = self.optim.state[p]
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for val in state.values():
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if isinstance(val, torch.Tensor):
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self.chunk_manager.add_extern_static_tensor(val)
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def state_dict(self, only_rank_0: bool = True):
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r"""Returns the state of the optimizer as a :class:`dict`. If only_rank_0 is True, for DP rank != 0, this function returns None.
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This saves memory usage.
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It contains two entries:
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* state - a dict holding current optimization state. Its content
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differs between optimizer classes.
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* param_groups - a list containing all parameter groups where each
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parameter group is a dict
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"""
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is_rank_0 = self.chunk_manager.process_group.dp_local_rank() == 0
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if not self.chunk_manager.enable_distributed_storage and only_rank_0 and not is_rank_0:
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return
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optim_state_dict = super().state_dict()
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scaler_state_dict = self.grad_scaler.state_dict()
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optim_state_dict['scaler'] = scaler_state_dict
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if not self.chunk_manager.enable_distributed_storage:
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return optim_state_dict
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local_state = {k: convert_state_dict_to_cpu(v) for k, v in optim_state_dict['state'].items() if len(v) > 0}
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if not self.chunk_manager.process_group.has_cpu_groups:
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self.chunk_manager.process_group.set_cpu_groups()
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output = [None for _ in range(self.chunk_manager.process_group.dp_world_size())]
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if only_rank_0:
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dst_rank = self.chunk_manager.process_group.dp_rank_list()[0]
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dist.gather_object(local_state,
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output if self.chunk_manager.process_group.dp_local_rank() == 0 else None,
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dst=dst_rank,
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group=self.chunk_manager.process_group.cpu_dp_process_group())
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if not is_rank_0:
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return
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else:
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dist.all_gather_object(output, local_state, group=self.chunk_manager.process_group.cpu_dp_process_group())
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for state in output:
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optim_state_dict['state'].update(state)
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return optim_state_dict
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def load_state_dict(self, state_dict):
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r"""Loads the optimizer state.
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Args:
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state_dict (dict): optimizer state. Should be an object returned
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from a call to :meth:`state_dict`.
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"""
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if 'scaler' not in state_dict:
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self._logger.warning('Missing scaler when loading optimizer state dict', ranks=[0])
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else:
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self.grad_scaler.load_state_dict(deepcopy(state_dict['scaler']))
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# Validate the state_dict
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groups = self.param_groups
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saved_groups = deepcopy(state_dict['param_groups'])
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if len(groups) != len(saved_groups):
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raise ValueError("loaded state dict has a different number of "
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"parameter groups")
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param_lens = (len(g['params']) for g in groups)
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saved_lens = (len(g['params']) for g in saved_groups)
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if any(p_len != s_len for p_len, s_len in zip(param_lens, saved_lens)):
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raise ValueError("loaded state dict contains a parameter group "
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"that doesn't match the size of optimizer's group")
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# Update the state
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id_map = {
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old_id: p for old_id, p in zip(chain.from_iterable((g['params'] for g in saved_groups
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)), chain.from_iterable((g['params'] for g in groups)))
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}
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def cast(param, value):
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r"""Make a deep copy of value, casting all tensors to device of param."""
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if isinstance(value, torch.Tensor):
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# Floating-point types are a bit special here. They are the only ones
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# that are assumed to always match the type of params.
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if param.is_floating_point():
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value = value.to(param.dtype)
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value = value.to(param.device)
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return value
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elif isinstance(value, dict):
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return {k: cast(param, v) for k, v in value.items()}
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elif isinstance(value, container_abcs.Iterable):
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return type(value)(cast(param, v) for v in value)
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else:
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return value
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# Copy state assigned to params (and cast tensors to appropriate types).
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# State that is not assigned to params is copied as is (needed for
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# backward compatibility).
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state = defaultdict(dict)
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for k, v in state_dict['state'].items():
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if k in id_map:
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param = self.fp16_param_to_fp32_param[id_map[k]]
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if param.storage().size() > 0:
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state[param] = cast(param, deepcopy(v))
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else:
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state[k] = deepcopy(v)
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# Update parameter groups, setting their 'params' value
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def update_group(group, new_group):
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new_group['params'] = group['params']
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return new_group
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param_groups = [update_group(g, ng) for g, ng in zip(groups, saved_groups)]
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self.__setstate__({'state': state, 'param_groups': param_groups})
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def convert_state_dict_to_cpu(state: Dict[str, torch.Tensor]):
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return {k: v.cpu() if isinstance(v, torch.Tensor) else v for k, v in state.items()}
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