# 在线量化示例

本示例介绍如何使用在线量化接口，来对训练好的分类模型进行量化, 可以减少模型的存储空间和显存占用。

## 接口介绍

请参考 量化API文档。

## 分类模型的离线量化流程

### 1. 配置量化参数

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    quant_config = {
        'weight_quantize_type': 'abs_max',
        'activation_quantize_type': 'moving_average_abs_max',
        'weight_bits': 8,
        'activation_bits': 8,
        'not_quant_pattern': ['skip_quant'],
        'quantize_op_types': ['conv2d', 'depthwise_conv2d', 'mul'],
        'dtype': 'int8',
        'window_size': 10000,
        'moving_rate': 0.9,
        'quant_weight_only': False
    }

### 2. 对训练和测试program插入可训练量化op

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    val_program = quant_aware(val_program, place, quant_config, scope=None, for_test=True)

    compiled_train_prog = quant_aware(train_prog, place, quant_config, scope=None, for_test=False)

### 3.关掉指定build策略

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    build_strategy = fluid.BuildStrategy()
    build_strategy.fuse_all_reduce_ops = False
    build_strategy.sync_batch_norm = False
    exec_strategy = fluid.ExecutionStrategy()
    compiled_train_prog = compiled_train_prog.with_data_parallel(
            loss_name=avg_cost.name,
            build_strategy=build_strategy,
            exec_strategy=exec_strategy)

### 4. freeze program

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    float_program, int8_program = convert(val_program,
                                          place,
                                          quant_config,
                                          scope=None,
                                          save_int8=True)

### 5.保存预测模型

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    fluid.io.save_inference_model(
        dirname=float_path,
        feeded_var_names=[image.name],
        target_vars=[out], executor=exe,
        main_program=float_program,
        model_filename=float_path + '/model',
        params_filename=float_path + '/params')

    fluid.io.save_inference_model(
        dirname=int8_path,
        feeded_var_names=[image.name],
        target_vars=[out], executor=exe,
        main_program=int8_program,
        model_filename=int8_path + '/model',
        params_filename=int8_path + '/params')

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