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paddlepaddle--paddle/python/paddle/quantization/imperative/ptq_quantizer.py
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2026-07-13 12:40:42 +08:00

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Python

# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
#
# 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.
import abc
import math
import numpy as np
import paddle
from ...static.quantization.cal_kl_threshold import cal_kl_threshold
from . import utils
def abs_max_value(tensor):
return float(paddle.max(paddle.abs(tensor)))
def merge_max_value(old, new):
"""
Merge the max element one by one in two lists.
"""
assert isinstance(old, list) and isinstance(new, list)
if old != []:
assert len(old) == len(new)
for i in range(len(old)):
assert type(old[i]) == type(new[i])
if isinstance(old[i], list):
new[i] = merge_max_value(old[i], new[i])
else:
new[i] = max(new[i], old[i])
return new
def combine_abs_max_and_hist(
tensor, origin_max, origin_hist, bins, upsample_bins
):
""" """
new_max = abs_max_value(tensor)
if new_max == 0.0:
return origin_max, origin_hist
elif origin_max == 0.0:
new_hist, _ = np.histogram(
paddle.abs(tensor).numpy(False), range=(0, new_max), bins=bins
)
new_hist = new_hist.astype(np.float32)
return new_max, new_hist
elif new_max <= origin_max:
new_hist, _ = np.histogram(
paddle.abs(tensor).numpy(False), range=(0, origin_max), bins=bins
)
new_hist = new_hist.astype(np.float32)
new_hist += origin_hist
return origin_max, new_hist
else:
# bin_width = origin_max / (bins * upsample_bins)
# = new_max / (bins * downsample_bins)
bin_width = origin_max / (bins * upsample_bins)
downsample_bins = int(math.ceil(new_max / (bins * bin_width)))
new_max = bins * bin_width * downsample_bins
upsampled_hist = np.repeat(origin_hist, upsample_bins)
expanded_hist = np.zeros((bins * downsample_bins), dtype=np.float32)
expanded_hist[0 : bins * upsample_bins] = upsampled_hist
cumsumed_hist = np.cumsum(expanded_hist, dtype=np.float64)[
downsample_bins - 1 :: downsample_bins
]
shift_cumsumed_hist = np.zeros((bins), dtype=np.float64)
shift_cumsumed_hist[1:] = cumsumed_hist[0:-1]
sampled_hist = (cumsumed_hist - shift_cumsumed_hist) / upsample_bins
sampled_hist = sampled_hist.astype(np.float32)
new_hist, _ = np.histogram(
paddle.abs(tensor).numpy(False), range=(0, new_max), bins=bins
)
new_hist = new_hist.astype(np.float32)
new_hist += sampled_hist
return new_max, new_hist
class BaseQuantizer(metaclass=abc.ABCMeta):
"""
Base quantizer for activation and weight.
"""
def __init__(self, quant_bits=8):
super().__init__()
assert isinstance(quant_bits, int)
assert quant_bits > 0 and quant_bits <= 16
self.quant_bits = quant_bits
self.abs_max_vals = []
self.thresholds = []
@abc.abstractmethod
def sample_data(self, layer, tensors):
pass
@abc.abstractmethod
def cal_thresholds(self):
pass
class AbsmaxQuantizer(BaseQuantizer):
"""
Per-tensor abs max quantizer.
"""
def __init__(self, quant_bits=8):
super().__init__(quant_bits)
def sample_data(self, layer, tensors):
assert isinstance(tensors, tuple)
abs_max_vals = [abs_max_value(t) for t in tensors]
self.abs_max_vals = merge_max_value(self.abs_max_vals, abs_max_vals)
def cal_thresholds(self):
self.thresholds = self.abs_max_vals
class PerChannelAbsmaxQuantizer(BaseQuantizer):
"""
Per channel abs max quantizer.
"""
def __init__(self, quant_bits=8):
super().__init__(quant_bits)
def sample_data(self, layer, tensors):
assert isinstance(layer, paddle.nn.Layer)
assert isinstance(tensors, tuple)
abs_max_vals_list = []
for idx, tensor in enumerate(tensors):
if isinstance(layer, tuple(utils.spec_channel_axis_layers)):
abs_max_vals = [
abs_max_value(tensor[:, i]) for i in range(tensor.shape[1])
]
abs_max_vals_list.append(abs_max_vals)
else:
abs_max_vals = [
abs_max_value(tensor[i]) for i in range(tensor.shape[0])
]
abs_max_vals_list.append(abs_max_vals)
self.abs_max_vals = merge_max_value(
self.abs_max_vals, abs_max_vals_list
)
def cal_thresholds(self):
self.thresholds = self.abs_max_vals
class BaseHistQuantizer(BaseQuantizer, metaclass=abc.ABCMeta):
""" """
def __init__(self, quant_bits=8, bins=1024, upsample_bins=64):
super().__init__(quant_bits)
self.bins = bins
self.upsample_bins = upsample_bins
self.hists = []
def sample_data(self, layer, tensors):
assert isinstance(tensors, tuple)
if self.abs_max_vals == []:
abs_max_vals = [abs_max_value(t) for t in tensors]
self.abs_max_vals = abs_max_vals
for idx, tensor in enumerate(tensors):
if abs_max_vals[idx] == 0.0:
self.hists.append(None)
else:
hist, _ = np.histogram(
paddle.abs(tensor).numpy(False),
range=(0.0, abs_max_vals[idx]),
bins=self.bins,
)
hist = hist.astype(np.float32)
self.hists.append(hist)
else:
assert len(self.abs_max_vals) == len(tensors)
assert len(self.hists) == len(tensors)
for idx, tensor in enumerate(tensors):
new_abs_max, new_hist = combine_abs_max_and_hist(
tensor,
self.abs_max_vals[idx],
self.hists[idx],
self.bins,
self.upsample_bins,
)
self.abs_max_vals[idx] = new_abs_max
self.hists[idx] = new_hist
@abc.abstractmethod
def cal_thresholds(self):
pass
class HistQuantizer(BaseHistQuantizer):
""" """
def __init__(
self, quant_bits=8, bins=1024, upsample_bins=64, hist_percent=0.99999
):
super().__init__(quant_bits, bins, upsample_bins)
self.hist_percent = hist_percent
def cal_thresholds(self):
def _helper(abs_max, hist, percent):
assert hist.ndim == 1 and percent < 1.0
hist = hist / np.sum(hist, dtype=np.float64)
cumsumed_hist = np.cumsum(hist)
index = np.argwhere(cumsumed_hist >= percent)[0]
return float((index - 0.5) * (abs_max / hist.shape[0]))
for idx in range(len(self.hists)):
if self.hists[idx] is None:
self.thresholds.append(self.abs_max_vals[idx])
else:
threshold = _helper(
self.abs_max_vals[idx], self.hists[idx], self.hist_percent
)
self.thresholds.append(threshold)
class KLQuantizer(BaseHistQuantizer):
""" """
def __init__(self, quant_bits=8, bins=1024, upsample_bins=64):
super().__init__(quant_bits, bins, upsample_bins)
def cal_thresholds(self):
for idx in range(len(self.hists)):
if self.hists[idx] is None:
self.thresholds.append(self.abs_max_vals[idx])
else:
hist = self.hists[idx]
abs_max_val = self.abs_max_vals[idx]
bin_width = abs_max_val / hist.shape[0]
threshold = cal_kl_threshold(hist, bin_width, self.quant_bits)
self.thresholds.append(threshold)
SUPPORT_ACT_QUANTIZERS = [AbsmaxQuantizer, HistQuantizer, KLQuantizer]
SUPPORT_WT_QUANTIZERS = [AbsmaxQuantizer, PerChannelAbsmaxQuantizer]