demo gpu模式测试

[Anglechina]

感谢，测试CPU已经通过，耗时大约0.3s，然后自己想测试GPU版本效果的时候发现时间和CPU效果一致，VisualizationDemo初始化的时候已经修改parallel为true，且开启了多次循环测试，发现时间还是和CPU相当。添加日志证明确实是调用的AsyncPredictor，您是否方便给些指导？已确认环境安装无误

[lucasjinreal]

@Anglechina Your test is already GPU mode not GPU mode, since in SOTR class it will convert model to cuda:

default is GPU.

In another words, this model, GPU speed is 100ms above. quite slow.