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# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved. | |
# SPDX-License-Identifier: Apache-2.0 | |
# | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
from typing import Optional | |
import numpy as np | |
from cosmos_predict1.utils import distributed, log | |
class TeroPolyScheduler: | |
def __init__( | |
self, | |
total_Mimg: int, | |
batch_size: int, | |
ref_Mimg: Optional[int] = None, | |
ref_batches: float = 70e3 / 1024, | |
max_lr_ratio: Optional[float] = 1.0, | |
min_lr_ratio: Optional[float] = None, | |
rampup_Mimg: float = 0, | |
rampdown_Mimg: int = 0, | |
verbosity_interval: int = 0, | |
formula: str = "poly", | |
poly_exp: float = 0.5, | |
): | |
self.total_Mimg = total_Mimg | |
self.batch_size = batch_size * distributed.get_world_size() | |
self.ref_Mimg = ref_Mimg or ref_batches * batch_size / 1e6 | |
self.ref_batches = ref_batches | |
self.max_lr_ratio = max_lr_ratio | |
self.min_lr_ratio = min_lr_ratio | |
self.rampup_Mimg = rampup_Mimg | |
self.rampdown_Mimg = rampdown_Mimg | |
self.verbosity_interval = verbosity_interval | |
self.formula = formula | |
self.poly_exp = poly_exp | |
self._model = None | |
def model(self): | |
return self._model | |
def model(self, model): | |
self._model = model | |
def schedule(self, n, **kwargs): | |
cur_Mimg = getattr(self.model, "sample_counter", 0) / 1e6 | |
if self.formula == "constant": | |
lr = 1.0 | |
elif self.formula == "poly": | |
lr = max(cur_Mimg / self.ref_Mimg, 1e-8) ** -self.poly_exp | |
else: | |
raise ValueError(f'Invalid learning rate formula "{self.formula}"') | |
if self.max_lr_ratio is not None: | |
lr = min(lr, self.max_lr_ratio) | |
if self.min_lr_ratio is not None: | |
lr = max(lr, self.min_lr_ratio) | |
if self.rampup_Mimg > 0 and cur_Mimg < self.rampup_Mimg: | |
lr *= cur_Mimg / self.rampup_Mimg | |
if self.rampdown_Mimg > 0 and cur_Mimg > self.total_Mimg - self.rampdown_Mimg: | |
lr *= (self.total_Mimg - cur_Mimg) / self.rampdown_Mimg | |
return lr | |
def __call__(self, n, **kwargs): | |
return self.schedule(n, **kwargs) | |
class LambdaWarmUpCosineScheduler: | |
""" | |
A learning rate scheduler that combines warm-up with a cosine decay schedule for multiple cycles. | |
It supports different configurations for each cycle, including the number of warm-up steps, minimum | |
and maximum scaling factors for the learning rate. | |
The scheduler is intended to be used with a base learning rate of 1.0, where the actual learning | |
rate at any step is the base learning rate multiplied by the scaling factor computed by the scheduler. | |
Parameters: | |
warm_up_steps (list[int]): List of integers where each element represents the number of warm-up | |
steps for the corresponding cycle. | |
f_min (list[float]): List of the minimum scaling factors for each cycle after warm-up. | |
f_max (list[float]): List of the maximum scaling factors at the start and end of each cosine cycle. | |
f_start (list[float]): List of starting scaling factors for each warm-up phase. | |
cycle_lengths (list[int]): List of the total lengths of each cycle, including warm-up steps. | |
verbosity_interval (int, optional): Interval of training steps at which to print current step and | |
scaling factor information. Set to 0 by default to disable verbosity. | |
Examples: | |
>>> scheduler = LambdaWarmUpCosineScheduler2( | |
warm_up_steps=[10, 10], | |
f_min=[0.1, 0.1], | |
f_max=[1.0, 1.0], | |
f_start=[0.01, 0.01], | |
cycle_lengths=[50, 50], | |
verbosity_interval=10) | |
>>> for step in range(100): | |
>>> lr_multiplier = scheduler(step) | |
>>> print(f"Step {step}: LR Multiplier = {lr_multiplier}") | |
""" | |
def __init__(self, warm_up_steps, f_min, f_max, f_start, cycle_lengths, verbosity_interval=0): | |
assert len(warm_up_steps) == len(f_min) == len(f_max) == len(f_start) == len(cycle_lengths) | |
self.lr_warm_up_steps = warm_up_steps | |
self.f_start = f_start | |
self.f_min = f_min | |
self.f_max = f_max | |
self.cycle_lengths = cycle_lengths | |
self.cum_cycles = np.cumsum([0] + list(self.cycle_lengths)) | |
self.last_f = 0.0 | |
self.verbosity_interval = verbosity_interval | |
def find_in_interval(self, n): | |
interval = 0 | |
for cl in self.cum_cycles[1:]: | |
if n <= cl: | |
return interval | |
interval += 1 | |
def schedule(self, n, **kwargs): | |
cycle = self.find_in_interval(n) | |
n = n - self.cum_cycles[cycle] | |
if self.verbosity_interval > 0: | |
if n % self.verbosity_interval == 0: | |
log.info(f"current step: {n}, recent lr-multiplier: {self.last_f}, " f"current cycle {cycle}") | |
if n < self.lr_warm_up_steps[cycle]: | |
f = (self.f_max[cycle] - self.f_start[cycle]) / self.lr_warm_up_steps[cycle] * n + self.f_start[cycle] | |
self.last_f = f | |
return f | |
else: | |
t = (n - self.lr_warm_up_steps[cycle]) / (self.cycle_lengths[cycle] - self.lr_warm_up_steps[cycle]) | |
t = min(t, 1.0) | |
f = self.f_min[cycle] + 0.5 * (self.f_max[cycle] - self.f_min[cycle]) * (1 + np.cos(t * np.pi)) | |
self.last_f = f | |
return f | |
def __call__(self, n, **kwargs): | |
return self.schedule(n, **kwargs) | |
class LambdaLinearScheduler(LambdaWarmUpCosineScheduler): | |
""" | |
Linear instead of cosine decay for the main part of the cycle. | |
""" | |
def schedule(self, n, **kwargs): | |
cycle = self.find_in_interval(n) | |
n = n - self.cum_cycles[cycle] | |
if self.verbosity_interval > 0: | |
if n % self.verbosity_interval == 0: | |
log.info(f"current step: {n}, recent lr-multiplier: {self.last_f}, " f"current cycle {cycle}") | |
if n < self.lr_warm_up_steps[cycle]: | |
f = (self.f_max[cycle] - self.f_start[cycle]) / self.lr_warm_up_steps[cycle] * n + self.f_start[cycle] | |
self.last_f = f | |
return f | |
else: | |
f = self.f_min[cycle] + (self.f_max[cycle] - self.f_min[cycle]) * (self.cycle_lengths[cycle] - n) / ( | |
self.cycle_lengths[cycle] - self.lr_warm_up_steps[cycle] | |
) | |
self.last_f = f | |
return f | |