[eigen] Different computation time when using Eige

[tuch s <tuchfly@xxxxxxxxx>]

I have used eigen to do the following computation in a deep learning programme，

Code: Select all

  cur->i = this->bi;
  cur->i.noalias() += this->Wxi*xt + this->Whi*prev->h;
  cur->f = this->bf;
  cur->f.noalias() += this->Wxf*xt + this->Whf*prev->h;
  cur->o = this->bo;
  cur->o.noalias() += this->Wxo*xt + this->Who*prev->h;
  cur->u = this->bu;
  cur->u.noalias() += this->Wxu*xt + this->Whu*prev->h;


W* is a matrix, and h, f, i, o, u are all vectors.

But I tried several times with the same input data， the time consuming is much different.
Some times it costs 0.4 second to get the output, but some times it cost 2.1 second to get the output.

 How can I solve this problem to get stable time cost ?