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53 lines
2.7 KiB
53 lines
2.7 KiB
from typing import List
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from torch.optim.lr_scheduler import MultiStepLR as _MultiStepLR
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from colossalai.registry import LR_SCHEDULERS
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from .delayed import WarmupScheduler
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@LR_SCHEDULERS.register_module
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class MultiStepLR(_MultiStepLR):
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"""Decays the learning rate of each parameter group by gamma once the
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number of epoch reaches one of the milestones. Notice that such decay can
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happen simultaneously with other changes to the learning rate from outside
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this scheduler. When last_epoch=-1, sets initial lr as lr.
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Args:
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optimizer (:class:`torch.optim.Optimizer`): Wrapped optimizer.
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total_steps (int): Number of total training steps.
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milestones (List[int], optional): List of epoch indices. Must be increasing, defaults to None.
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gamma (float, optional): Multiplicative factor of learning rate decay, defaults to 0.1.
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last_epoch (int, optional): The index of last epoch, defaults to -1. When last_epoch=-1,
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the schedule is started from the beginning or When last_epoch=-1, sets initial lr as lr.
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"""
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def __init__(self, optimizer, total_steps: int, milestones: List[int] = None, gamma: float = 0.1, last_epoch: int = -1, **kwargs):
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super().__init__(optimizer, milestones, gamma=gamma, last_epoch=last_epoch)
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@LR_SCHEDULERS.register_module
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class MultiStepWarmupLR(WarmupScheduler):
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"""Multistep learning rate scheduler with warmup.
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Args:
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optimizer (:class:`torch.optim.Optimizer`): Wrapped optimizer.
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total_steps (int): Number of total training steps.
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warmup_steps (int, optional): Number of warmup steps, defaults to 0.
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milestones (List[int], optional): List of epoch indices. Must be increasing, defaults to None.
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gamma (float, optional): Multiplicative factor of learning rate decay, defaults to 0.1.
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num_steps_per_epoch (int, optional): Number of steps per epoch, defaults to -1.
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last_epoch (int, optional): The index of last epoch, defaults to -1. When last_epoch=-1,
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the schedule is started from the beginning or When last_epoch=-1, sets initial lr as lr.
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"""
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def __init__(self, optimizer, total_steps: int, warmup_steps: int = 0, milestones: List[int] = None,
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gamma: float = 0.1, last_epoch: int = -1, **kwargs):
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if len(milestones) == 0:
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raise ValueError('milestones cannot be empty')
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milestones = [
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v - warmup_steps for v in milestones if v >= warmup_steps]
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base_scheduler = _MultiStepLR(optimizer, milestones=milestones,
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gamma=gamma)
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super().__init__(optimizer, warmup_steps, base_scheduler, last_epoch=last_epoch)
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