Created by: dzhwinter

fix https://github.com/PaddlePaddle/Paddle/issues/9460 There are some conclusions.

1. profiler count the max time cost is not accurate. Inside PushEvent, PopEvent, it uses the mutex lock, and make it sometime have peak value happens.
2. The Eigen operation will degrade when process large input data. For example, the scale_op implement based on Eigen scalar * Tensor operation.

The input data has an instance longer than others noteblely, its' max value goes to 2.95648.

Event                                     Calls       Total       Min.        Max.        Ave.
thread0::scale                            64100       1743.01     0.016128    2.95648     0.0271921

If we crop the input size to the same length. Then it goes

Event                                     Calls       Total       Min.        Max.        Ave.
thread0::scale                            5200        123.396     0.019424    0.071616    0.02373```