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from abc import abstractmethod |
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from contextlib import contextmanager |
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from typing import Tuple |
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import torch |
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import torch.nn as nn |
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import numpy as np |
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class MemoryController: |
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""" |
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Base class for memory management during training. |
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""" |
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_last_input_size = None |
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_last_mem_ratio = [] |
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@contextmanager |
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def record(self): |
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pass |
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def update_run_states(self, input_size=None, mem_ratio=None): |
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if self._last_input_size is None: |
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self._last_input_size = input_size |
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elif self._last_input_size!= input_size: |
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raise ValueError(f'Input size should not change for different ElasticModules.') |
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self._last_mem_ratio.append(mem_ratio) |
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@abstractmethod |
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def get_mem_ratio(self, input_size): |
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pass |
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@abstractmethod |
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def state_dict(self): |
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pass |
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@abstractmethod |
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def log(self): |
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pass |
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class LinearMemoryController(MemoryController): |
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""" |
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A simple controller for memory management during training. |
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The memory usage is modeled as a linear function of: |
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- the number of input parameters |
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- the ratio of memory the model use compared to the maximum usage (with no checkpointing) |
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memory_usage = k * input_size * mem_ratio + b |
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The controller keeps track of the memory usage and gives the |
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expected memory ratio to keep the memory usage under a target |
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""" |
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def __init__( |
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self, |
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buffer_size=1000, |
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update_every=500, |
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target_ratio=0.8, |
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available_memory=None, |
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max_mem_ratio_start=0.1, |
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params=None, |
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device=None |
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): |
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self.buffer_size = buffer_size |
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self.update_every = update_every |
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self.target_ratio = target_ratio |
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self.device = device or torch.cuda.current_device() |
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self.available_memory = available_memory or torch.cuda.get_device_properties(self.device).total_memory / 1024**3 |
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self._memory = np.zeros(buffer_size, dtype=np.float32) |
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self._input_size = np.zeros(buffer_size, dtype=np.float32) |
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self._mem_ratio = np.zeros(buffer_size, dtype=np.float32) |
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self._buffer_ptr = 0 |
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self._buffer_length = 0 |
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self._params = tuple(params) if params is not None else (0.0, 0.0) |
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self._max_mem_ratio = max_mem_ratio_start |
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self.step = 0 |
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def __repr__(self): |
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return f'LinearMemoryController(target_ratio={self.target_ratio}, available_memory={self.available_memory})' |
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def _add_sample(self, memory, input_size, mem_ratio): |
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self._memory[self._buffer_ptr] = memory |
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self._input_size[self._buffer_ptr] = input_size |
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self._mem_ratio[self._buffer_ptr] = mem_ratio |
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self._buffer_ptr = (self._buffer_ptr + 1) % self.buffer_size |
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self._buffer_length = min(self._buffer_length + 1, self.buffer_size) |
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@contextmanager |
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def record(self): |
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torch.cuda.reset_peak_memory_stats(self.device) |
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self._last_input_size = None |
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self._last_mem_ratio = [] |
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yield |
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self._last_memory = torch.cuda.max_memory_allocated(self.device) / 1024**3 |
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self._last_mem_ratio = sum(self._last_mem_ratio) / len(self._last_mem_ratio) |
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self._add_sample(self._last_memory, self._last_input_size, self._last_mem_ratio) |
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self.step += 1 |
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if self.step % self.update_every == 0: |
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self._max_mem_ratio = min(1.0, self._max_mem_ratio + 0.1) |
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self._fit_params() |
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def _fit_params(self): |
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memory_usage = self._memory[:self._buffer_length] |
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input_size = self._input_size[:self._buffer_length] |
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mem_ratio = self._mem_ratio[:self._buffer_length] |
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x = input_size * mem_ratio |
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y = memory_usage |
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k, b = np.polyfit(x, y, 1) |
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self._params = (k, b) |
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def _visualize(self): |
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import matplotlib.pyplot as plt |
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memory_usage = self._memory[:self._buffer_length] |
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input_size = self._input_size[:self._buffer_length] |
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mem_ratio = self._mem_ratio[:self._buffer_length] |
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k, b = self._params |
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plt.scatter(input_size * mem_ratio, memory_usage, c=mem_ratio, cmap='viridis') |
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x = np.array([0.0, 20000.0]) |
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plt.plot(x, k * x + b, c='r') |
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plt.savefig(f'linear_memory_controller_{self.step}.png') |
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plt.cla() |
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def get_mem_ratio(self, input_size): |
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k, b = self._params |
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if k == 0: return np.random.rand() * self._max_mem_ratio |
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pred = (self.available_memory * self.target_ratio - b) / (k * input_size) |
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return min(self._max_mem_ratio, max(0.0, pred)) |
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def state_dict(self): |
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return { |
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'params': self._params, |
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} |
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def load_state_dict(self, state_dict): |
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self._params = tuple(state_dict['params']) |
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def log(self): |
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return { |
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'params/k': self._params[0], |
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'params/b': self._params[1], |
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'memory': self._last_memory, |
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'input_size': self._last_input_size, |
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'mem_ratio': self._last_mem_ratio, |
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} |
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class ElasticModule(nn.Module): |
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""" |
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Module for training with elastic memory management. |
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""" |
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def __init__(self): |
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super().__init__() |
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self._memory_controller: MemoryController = None |
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@abstractmethod |
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def _get_input_size(self, *args, **kwargs) -> int: |
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""" |
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Get the size of the input data. |
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Returns: |
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int: The size of the input data. |
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""" |
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pass |
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@abstractmethod |
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def _forward_with_mem_ratio(self, *args, mem_ratio=0.0, **kwargs) -> Tuple[float, Tuple]: |
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""" |
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Forward with a given memory ratio. |
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""" |
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pass |
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def register_memory_controller(self, memory_controller: MemoryController): |
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self._memory_controller = memory_controller |
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def forward(self, *args, **kwargs): |
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if self._memory_controller is None or not torch.is_grad_enabled() or not self.training: |
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_, ret = self._forward_with_mem_ratio(*args, **kwargs) |
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else: |
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input_size = self._get_input_size(*args, **kwargs) |
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mem_ratio = self._memory_controller.get_mem_ratio(input_size) |
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mem_ratio, ret = self._forward_with_mem_ratio(*args, mem_ratio=mem_ratio, **kwargs) |
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self._memory_controller.update_run_states(input_size, mem_ratio) |
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return ret |
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class ElasticModuleMixin: |
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""" |
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Mixin for training with elastic memory management. |
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""" |
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def __init__(self, *args, **kwargs): |
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super().__init__(*args, **kwargs) |
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self._memory_controller: MemoryController = None |
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@abstractmethod |
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def _get_input_size(self, *args, **kwargs) -> int: |
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""" |
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Get the size of the input data. |
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Returns: |
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int: The size of the input data. |
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""" |
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pass |
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@abstractmethod |
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@contextmanager |
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def with_mem_ratio(self, mem_ratio=1.0) -> float: |
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""" |
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Context manager for training with a reduced memory ratio compared to the full memory usage. |
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Returns: |
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float: The exact memory ratio used during the forward pass. |
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""" |
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pass |
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def register_memory_controller(self, memory_controller: MemoryController): |
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self._memory_controller = memory_controller |
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def forward(self, *args, **kwargs): |
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if self._memory_controller is None or not torch.is_grad_enabled() or not self.training: |
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ret = super().forward(*args, **kwargs) |
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else: |
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input_size = self._get_input_size(*args, **kwargs) |
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mem_ratio = self._memory_controller.get_mem_ratio(input_size) |
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with self.with_mem_ratio(mem_ratio) as exact_mem_ratio: |
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ret = super().forward(*args, **kwargs) |
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self._memory_controller.update_run_states(input_size, exact_mem_ratio) |
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return ret |
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