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add new post-quant methods #32208

Merged
merged 3 commits into from
Apr 14, 2021
Merged

add new post-quant methods #32208

merged 3 commits into from
Apr 14, 2021

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XGZhang11
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@XGZhang11 XGZhang11 commented Apr 12, 2021

PR types

Performance optimization

PR changes

APIs

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1.Add new methods: 'mse', 'hist', 'avg' of getting threshold values of activations for post-training quantization in 'post_training_quantization.py'.
2.Add bias correction method in of https://arxiv.org/abs/1810.05723 for post-training quantization in 'quantization_pass.py'. Bias correction changes the quantized weights by the following formulation:
image

Experimental results on 6-bit MobileNetV1 which calibrated by a batch of 32 images:
abs_max: 44.99 abs_max+bias_correction: 47.91
avg: 56.34 avg+bias_correction: 56.17
mse: 61.32 mse+bias_correction: 61.42
hist(0.9999): 60.72 hist+bias_correction: 62.44
KL: 53.11 KL+bias_correction: 58.46

Time cost: Abs_max and avg cost about 1 minute; hist and KL cost about 6 minutes; mse cost about 10 minutes. Bias correction cost little time.

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Thanks for your contribution!
Please wait for the result of CI firstly. See Paddle CI Manual for details.

@wanghaoshuang
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请为新增代码补充下单测。

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@juncaipeng juncaipeng left a comment

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请添加相应单侧,要不然代码覆盖率达不到,参考../tests/下面的单侧示例。

不同方法的实验数据最好贴到pr上,包括量化模型精度、量化过程的时间等。

@@ -138,8 +138,10 @@ def __init__(self,
batch_size=10,
batch_nums=None,
algo="KL",
hist_perc=0.99999,
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建议用完整的hist_percent

quantizable_op_type=["conv2d", "depthwise_conv2d", "mul"],
is_full_quantize=False,
bias_correct=False,
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bias_correction?

@@ -373,14 +389,17 @@ def quantize(self):
batch_id += 1
if self._batch_nums and batch_id >= self._batch_nums:
break

if self._algo == 'avg':
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这是获取阈值的逻辑,后面计算阈值的部分。

if self._algo == "abs_max":
self._sample_abs_max()
if self._algo in ["avg", "abs_max"]:
self._sample_abs_max_avg()
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两个不相同的采样方式,分开成两个函数。

if mse_loss <= self._best_mse_loss[var_name]:
self._best_mse_loss[var_name] = mse_loss
best_scale = scale
if best_scale > 0.0:
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这个判断没有必要,self._quantized_threshold[var_name] = best_scale 可以放到if mse_loss <= self._best_mse_loss[var_name]:中

save_info(
op_node, out_var_name, self._quantized_threshold,
argname_index[0] + str(argname_index[1]) + "_threshold",
"post_absmax")
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三种方法有点点差别,建议区分开来

if self._algo == 'avg':
if (var_name not in self._quantized_var_avg):
self._quantized_var_avg[var_name] = []
abs_avg_value = float(np.mean(np.max(np.abs(var_tensor.reshape(var_tensor.shape[0], -1)), axis=(1))))
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注意代码每行的长度

@@ -1154,7 +1158,35 @@ def apply(self, graph):
else:
quant_axis = 0
quantized_param_v = self._quant(
param_v, scale_v, self._weight_bits, quant_axis)
param_v.copy(), scale_v, self._weight_bits, quant_axis)
if self._bias_correct == True:
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将bias_correction功能独立为一个函数实现

if isinstance(scale_v, list):
if quant_axis == 0:
for i, s in enumerate(scale_v):
quantized_param_v[i] = quantized_param_v[i] * s / bnt
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这是dequantized_param_v了

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LGTM

@wanghaoshuang wanghaoshuang merged commit 4281eb4 into PaddlePaddle:develop Apr 14, 2021
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3 participants