mirror of
https://github.com/zebrajr/pytorch.git
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a58ff186e8
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/65443 Test Plan: Imported from OSS Reviewed By: dagitses, supriyar Differential Revision: D31456445 Pulled By: b-koopman fbshipit-source-id: 0edda6e272d9005fce65f2ba6a5e6abc831836de
405 lines
18 KiB
Python
405 lines
18 KiB
Python
import torch
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from torch.nn import Module
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from torch.ao.quantization.observer import (
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MovingAverageMinMaxObserver,
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HistogramObserver,
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MovingAveragePerChannelMinMaxObserver,
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PerChannelMinMaxObserver,
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_with_args,
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)
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import re
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from abc import ABC, abstractmethod
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from typing import Any, Tuple
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def _is_per_channel(qscheme: 'torch.qscheme') -> bool:
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return qscheme in [torch.per_channel_symmetric, torch.per_channel_affine, torch.per_channel_affine_float_qparams]
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def _is_per_tensor(qscheme: 'torch.qscheme') -> bool:
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return qscheme in [torch.per_tensor_symmetric, torch.per_tensor_affine]
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def _is_symmetric_quant(qscheme: 'torch.qscheme') -> bool:
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return qscheme in [torch.per_tensor_symmetric, torch.per_channel_symmetric]
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class FakeQuantizeBase(ABC, Module):
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r""" Base fake quantize module
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Any fake quantize implementation should derive from this class.
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Concrete fake quantize module should follow the same API. In forward, they will update
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the statistics of the observed Tensor and fake quantize the input. They should also provide a
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`calculate_qparams` function that computes the quantization parameters given
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the collected statistics.
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"""
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fake_quant_enabled: torch.Tensor
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observer_enabled: torch.Tensor
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def __init__(self):
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super().__init__()
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# fake_quant_enabled and observer_enabled are buffers to support their
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# replication in DDP. Data type is uint8 because NCCL does not support
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# bool tensors.
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self.register_buffer('fake_quant_enabled', torch.tensor([1], dtype=torch.uint8))
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self.register_buffer('observer_enabled', torch.tensor([1], dtype=torch.uint8))
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@abstractmethod
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def forward(self, x):
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pass
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@abstractmethod
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def calculate_qparams(self, **kwargs):
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pass
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@torch.jit.export
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def enable_fake_quant(self, enabled: bool = True) -> None:
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self.fake_quant_enabled[0] = 1 if enabled else 0
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@torch.jit.export
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def disable_fake_quant(self):
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self.enable_fake_quant(False)
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@torch.jit.export
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def enable_observer(self, enabled: bool = True) -> None:
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self.observer_enabled[0] = 1 if enabled else 0
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@torch.jit.export
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def disable_observer(self):
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self.enable_observer(False)
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with_args = classmethod(_with_args)
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class FakeQuantize(FakeQuantizeBase):
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r""" Simulate the quantize and dequantize operations in training time.
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The output of this module is given by
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x_out = (clamp(round(x/scale + zero_point), quant_min, quant_max)-zero_point)*scale
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* :attr:`scale` defines the scale factor used for quantization.
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* :attr:`zero_point` specifies the quantized value to which 0 in floating point maps to
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* :attr:`quant_min` specifies the minimum allowable quantized value.
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* :attr:`quant_max` specifies the maximum allowable quantized value.
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* :attr:`fake_quant_enable` controls the application of fake quantization on tensors, note that
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statistics can still be updated.
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* :attr:`observer_enable` controls statistics collection on tensors
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* :attr:`dtype` specifies the quantized dtype that is being emulated with fake-quantization,
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allowable values are torch.qint8 and torch.quint8. The values of quant_min and
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quant_max should be chosen to be consistent with the dtype
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Args:
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observer (module): Module for observing statistics on input tensors and calculating scale
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and zero-point.
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quant_min (int): The minimum allowable quantized value.
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quant_max (int): The maximum allowable quantized value.
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observer_kwargs (optional): Arguments for the observer module
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Attributes:
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observer (Module): User provided module that collects statistics on the input tensor and
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provides a method to calculate scale and zero-point.
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"""
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scale: torch.Tensor
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zero_point: torch.Tensor
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def __init__(self, observer=MovingAverageMinMaxObserver, quant_min=0, quant_max=255, **observer_kwargs):
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super().__init__()
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assert quant_min <= quant_max, \
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'quant_min must be less than or equal to quant_max'
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self.quant_min = quant_min
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self.quant_max = quant_max
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self.activation_post_process = observer(**observer_kwargs)
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assert torch.iinfo(self.activation_post_process.dtype).min <= quant_min, 'quant_min out of bound'
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assert quant_max <= torch.iinfo(self.activation_post_process.dtype).max, 'quant_max out of bound'
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self.register_buffer('scale', torch.tensor([1.0], dtype=torch.float))
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self.register_buffer('zero_point', torch.tensor([0], dtype=torch.int))
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self.dtype = self.activation_post_process.dtype
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self.qscheme = self.activation_post_process.qscheme
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self.ch_axis = self.activation_post_process.ch_axis \
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if hasattr(self.activation_post_process, 'ch_axis') else -1
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assert _is_per_channel(self.qscheme) or \
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_is_per_tensor(self.qscheme), \
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'Only per channel and per tensor quantization are supported in fake quantize' + \
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' got qscheme: ' + str(self.qscheme)
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self.is_per_channel = _is_per_channel(self.qscheme)
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@torch.jit.export
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def calculate_qparams(self):
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return self.activation_post_process.calculate_qparams()
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def forward(self, X):
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if self.observer_enabled[0] == 1:
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self.activation_post_process(X.detach())
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_scale, _zero_point = self.calculate_qparams()
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_scale, _zero_point = _scale.to(self.scale.device), _zero_point.to(self.zero_point.device)
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if self.scale.shape != _scale.shape:
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self.scale.resize_(_scale.shape)
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self.zero_point.resize_(_zero_point.shape)
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self.scale.copy_(_scale)
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self.zero_point.copy_(_zero_point)
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if self.fake_quant_enabled[0] == 1:
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if self.is_per_channel:
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X = torch.fake_quantize_per_channel_affine(
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X, self.scale, self.zero_point,
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self.ch_axis, self.quant_min, self.quant_max)
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else:
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X = torch.fake_quantize_per_tensor_affine(
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X, self.scale, self.zero_point,
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self.quant_min, self.quant_max)
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return X
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@torch.jit.export
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def extra_repr(self):
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return 'fake_quant_enabled={}, observer_enabled={}, ' \
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'quant_min={}, quant_max={}, dtype={}, qscheme={}, ch_axis={}, ' \
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'scale={}, zero_point={}'.format(
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self.fake_quant_enabled, self.observer_enabled,
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self.quant_min, self.quant_max,
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self.dtype, self.qscheme, self.ch_axis, self.scale, self.zero_point)
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def _save_to_state_dict(self, destination, prefix, keep_vars):
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# We cannot currently register scalar values as buffers, so need to manually
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# specify serialization here.
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super(FakeQuantize, self)._save_to_state_dict(destination, prefix, keep_vars)
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destination[prefix + 'scale'] = self.scale
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destination[prefix + 'zero_point'] = self.zero_point
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def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict,
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missing_keys, unexpected_keys, error_msgs):
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# Removing this function throws an error that the the size of the loaded tensor does not match the original size
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# i.e., These buffers start out with numel 0 and become numel 1 once they have their first forward pass.
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local_state = ['scale', 'zero_point']
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for name in local_state:
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key = prefix + name
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if key in state_dict:
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val = state_dict[key]
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# Custom handling to allow loading scale and zero_point
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# of size N into uninitialized buffers of size 0. The
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# buffers are resized here, and the values are copied in
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# the default state_dict loading code of the parent.
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if name == 'scale':
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self.scale.resize_(val.shape)
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else:
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assert name == 'zero_point'
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self.zero_point.resize_(val.shape)
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# For torchscript module we need to update the attributes here since we do not
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# call the `_load_from_state_dict` function defined module.py
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if torch.jit.is_scripting():
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if name == 'scale':
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self.scale.copy_(val)
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else:
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assert name == 'zero_point'
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self.zero_point.copy_(val)
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elif strict:
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missing_keys.append(key)
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super(FakeQuantize, self)._load_from_state_dict(state_dict, prefix, local_metadata, strict,
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missing_keys, unexpected_keys, error_msgs)
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class FixedQParamsFakeQuantize(FakeQuantizeBase):
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""" Simulate quantize and dequantize with fixed quantization
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parameters in training time. Only per tensor quantization
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is supported.
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Args:
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`scale` (float): fixed scale for the fake quantize module
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`zero_point` (int): fixed zero point for the fake quantize module
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`dtype`, `qscheme`, `quant_min`, `quant_max`
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"""
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scale: torch.Tensor
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zero_point: torch.Tensor
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def __init__(self,
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scale,
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zero_point,
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dtype=torch.quint8,
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qscheme=torch.per_tensor_affine,
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quant_min=0,
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quant_max=255):
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super().__init__()
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assert quant_min <= quant_max, 'quant_min should be less than or equal to quant_max'
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self.quant_min = quant_min
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self.quant_max = quant_max
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self.register_buffer('scale', torch.tensor([scale], dtype=torch.float))
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self.register_buffer('zero_point', torch.tensor([zero_point], dtype=torch.int))
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self.dtype = dtype
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self.qscheme = qscheme
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assert _is_per_tensor(self.qscheme), 'Only per tensor quantization is supported' + \
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' FixedQParamsFakeQuantize module, got qscheme:' + str(self.qscheme)
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def forward(self, X):
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if self.fake_quant_enabled[0] == 1:
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X = torch.fake_quantize_per_tensor_affine(X, self.scale,
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self.zero_point, self.quant_min,
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self.quant_max)
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return X
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@torch.jit.export
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def calculate_qparams(self):
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return self.scale, self.zero_point
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@torch.jit.export
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def extra_repr(self):
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return 'fake_quant_enabled={}, observer_enabled={}, scale={}, zero_point={}, ' \
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'dtype={}, quant_min={}, quant_max={}, qscheme={}'.format(
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self.fake_quant_enabled, self.observer_enabled,
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self.scale, self.zero_point, self.dtype,
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self.quant_min, self.quant_max, self.qscheme)
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class FusedMovingAvgObsFakeQuantize(FakeQuantize):
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r"""Fused module that is used to observe the input tensor (compute min/max), compute
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scale/zero_point and fake_quantize the tensor.
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This module uses calculation similar MovingAverageMinMaxObserver for the inputs,
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to compute the min/max values in order to compute the scale/zero_point.
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The qscheme input in the observer is used to differentiate between symmetric/affine
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quantization scheme.
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The output of this module is given by
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x_out = (clamp(round(x/scale + zero_point), quant_min, quant_max)-zero_point)*scale
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Similar to :class:`~torch.ao.quantization.FakeQuantize`, and accepts the same attributes as the
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base class.
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"""
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def __init__(
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self,
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observer: Any = MovingAverageMinMaxObserver,
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quant_min: int = 0,
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quant_max: int = 255,
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**observer_kwargs: Any
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) -> None:
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super().__init__(observer, quant_min, quant_max, **observer_kwargs)
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assert isinstance(self.activation_post_process, (MovingAverageMinMaxObserver, MovingAveragePerChannelMinMaxObserver)),\
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"Fused observer+fake_quant module only works with MovingAverageMinMaxObserver"
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self.quant_min: int = quant_min
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self.quant_max: int = quant_max
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self.register_buffer("fake_quant_enabled", torch.tensor([1], dtype=torch.long))
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self.register_buffer("observer_enabled", torch.tensor([1], dtype=torch.long))
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self.is_symmetric_quant = _is_symmetric_quant(self.activation_post_process.qscheme)
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self.quant_min, self.quant_max = self.activation_post_process.quant_min, self.activation_post_process.quant_max
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@torch.jit.export
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def calculate_qparams(self) -> Tuple[torch.Tensor, torch.Tensor]:
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return self.activation_post_process.calculate_qparams()
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@torch.jit.export
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def extra_repr(self) -> str:
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return (
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"fake_quant_enabled={}, observer_enabled={}, scale={}, zero_point={}, "
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"dtype={}, quant_min={}, quant_max={}, qscheme={}, reduce_range={}".format(
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self.fake_quant_enabled,
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self.observer_enabled,
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self.scale,
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self.zero_point,
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self.dtype,
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self.quant_min,
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self.quant_max,
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self.qscheme,
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self.activation_post_process.reduce_range,
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)
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)
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def forward(self, X: torch.Tensor) -> torch.Tensor:
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return torch.fused_moving_avg_obs_fake_quant(
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X,
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self.observer_enabled,
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self.fake_quant_enabled,
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self.activation_post_process.min_val,
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self.activation_post_process.max_val,
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self.scale,
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self.zero_point,
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self.activation_post_process.averaging_constant,
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self.quant_min,
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self.quant_max,
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self.ch_axis,
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self.is_per_channel,
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self.is_symmetric_quant,
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)
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default_fake_quant = FakeQuantize.with_args(observer=MovingAverageMinMaxObserver, quant_min=0, quant_max=255,
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dtype=torch.quint8, qscheme=torch.per_tensor_affine, reduce_range=True)
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default_weight_fake_quant = FakeQuantize.with_args(observer=MovingAverageMinMaxObserver, quant_min=-128, quant_max=127,
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dtype=torch.qint8, qscheme=torch.per_tensor_symmetric, reduce_range=False)
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# TODO(future PR): remove these defaults and enforce activation functions
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# to explicitly specify their output range
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default_symmetric_fixed_qparams_fake_quant = FixedQParamsFakeQuantize.with_args(
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scale=2.0 / 256.0, zero_point=128, dtype=torch.quint8, quant_min=0, quant_max=255)
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default_affine_fixed_qparams_fake_quant = FixedQParamsFakeQuantize.with_args(
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scale=1.0 / 256.0, zero_point=0, dtype=torch.quint8, quant_min=0, quant_max=255)
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default_per_channel_weight_fake_quant = FakeQuantize.with_args(observer=MovingAveragePerChannelMinMaxObserver,
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quant_min=-128,
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quant_max=127,
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dtype=torch.qint8,
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qscheme=torch.per_channel_symmetric,
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reduce_range=False,
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ch_axis=0)
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default_embedding_fake_quant = FakeQuantize.with_args(observer=PerChannelMinMaxObserver,
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qscheme=torch.per_channel_affine_float_qparams,
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ch_axis=0,
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memoryless=True)
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default_histogram_fake_quant = FakeQuantize.with_args(observer=HistogramObserver,
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quant_min=0,
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quant_max=255,
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dtype=torch.quint8,
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qscheme=torch.per_tensor_affine,
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reduce_range=True)
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default_fused_act_fake_quant = FusedMovingAvgObsFakeQuantize.with_args(observer=MovingAverageMinMaxObserver,
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quant_min=0,
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quant_max=255,
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dtype=torch.quint8,)
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default_fused_wt_fake_quant = FusedMovingAvgObsFakeQuantize.with_args(observer=MovingAverageMinMaxObserver,
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quant_min=-128,
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quant_max=127,
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dtype=torch.qint8,
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qscheme=torch.per_tensor_symmetric)
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default_fused_per_channel_wt_fake_quant = FusedMovingAvgObsFakeQuantize.with_args(observer=MovingAveragePerChannelMinMaxObserver,
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quant_min=-128,
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quant_max=127,
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dtype=torch.qint8,
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qscheme=torch.per_channel_symmetric)
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def _is_fake_quant_script_module(mod):
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''' Returns true if given mod is an instance of FakeQuantize script module.
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'''
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if isinstance(mod, torch.jit.RecursiveScriptModule):
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# qualified name looks like '__torch__.torch.ao.quantization.fake_quantize.___torch_mangle_2.FakeQuantize'
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suffix = mod._c.qualified_name.split('.', 1)[1]
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name = re.sub(r'\.___torch_mangle_\d+', '', suffix)
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return name == 'torch.ao.quantization.fake_quantize.FakeQuantize' or \
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name == 'torch.ao.quantization.fake_quantize.FusedMovingAvgObsFakeQuantize'
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return False
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def disable_fake_quant(mod):
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if isinstance(mod, FakeQuantizeBase) or _is_fake_quant_script_module(mod):
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mod.disable_fake_quant()
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def enable_fake_quant(mod):
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if isinstance(mod, FakeQuantizeBase) or _is_fake_quant_script_module(mod):
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mod.enable_fake_quant()
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def disable_observer(mod):
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if isinstance(mod, FakeQuantizeBase) or _is_fake_quant_script_module(mod):
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mod.disable_observer()
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def enable_observer(mod):
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if isinstance(mod, FakeQuantizeBase) or _is_fake_quant_script_module(mod):
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mod.enable_observer()
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