cyclic_40e.py

# Copyright (c) OpenMMLab. All rights reserved.
from mmengine.optim.optimizer.optimizer_wrapper import OptimWrapper
from mmengine.optim.scheduler.lr_scheduler import CosineAnnealingLR
from mmengine.optim.scheduler.momentum_scheduler import CosineAnnealingMomentum
from torch.optim.adamw import AdamW

# The schedule is usually used by models trained on KITTI dataset
# The learning rate set in the cyclic schedule is the initial learning rate
# rather than the max learning rate. Since the target_ratio is (10, 1e-4),
# the learning rate will change from 0.0018 to 0.018, than go to 0.0018*1e-4
lr = 0.0018
# The optimizer follows the setting in SECOND.Pytorch, but here we use
# the official AdamW optimizer implemented by PyTorch.
optim_wrapper = dict(
    type=OptimWrapper,
    optimizer=dict(type=AdamW, lr=lr, betas=(0.95, 0.99), weight_decay=0.01),
    clip_grad=dict(max_norm=10, norm_type=2))
# learning rate
param_scheduler = [
    # learning rate scheduler
    # During the first 16 epochs, learning rate increases from 0 to lr * 10
    # during the next 24 epochs, learning rate decreases from lr * 10 to
    # lr * 1e-4
    dict(
        type=CosineAnnealingLR,
        T_max=16,
        eta_min=lr * 10,
        begin=0,
        end=16,
        by_epoch=True,
        convert_to_iter_based=True),
    dict(
        type=CosineAnnealingLR,
        T_max=24,
        eta_min=lr * 1e-4,
        begin=16,
        end=40,
        by_epoch=True,
        convert_to_iter_based=True),
    # momentum scheduler
    # During the first 16 epochs, momentum increases from 0 to 0.85 / 0.95
    # during the next 24 epochs, momentum increases from 0.85 / 0.95 to 1
    dict(
        type=CosineAnnealingMomentum,
        T_max=16,
        eta_min=0.85 / 0.95,
        begin=0,
        end=16,
        by_epoch=True,
        convert_to_iter_based=True),
    dict(
        type=CosineAnnealingMomentum,
        T_max=24,
        eta_min=1,
        begin=16,
        end=40,
        by_epoch=True,
        convert_to_iter_based=True)
]

# Runtime settings，training schedule for 40e
# Although the max_epochs is 40, this schedule is usually used we
# RepeatDataset with repeat ratio N, thus the actual max epoch
# number could be Nx40
train_cfg = dict(by_epoch=True, max_epochs=40, val_interval=1)
val_cfg = dict()
test_cfg = dict()

# Default setting for scaling LR automatically
#   - `enable` means enable scaling LR automatically
#       or not by default.
#   - `base_batch_size` = (8 GPUs) x (6 samples per GPU).
auto_scale_lr = dict(enable=False, base_batch_size=48)