Automated parallelizing not working with large matrixes

[suarez__eric]

I have a code in fortran that calculates eigenvectors and eigenfunctions of matrix and process the results. I use the ifort with the -mkl compilation, the code runs in parallel for an square matrix (N,N) when N is less than 100 (more or less) but when I try larger matrixes N>300 it only runs as one thread. 

Any help?

Regards

Eric

[Steven_L_Intel1]

Please clarify - are you using MKL routines for the eigenvectors and eigenfunctions? Which routines?

[suarez__eric]

yes, I am calling  zheev to calculate the eigenvalues and eigenvectors then I do some other calculations with the results.

[Steven_L_Intel1]

Ok. I am going to move this to the MKL forum, then, where MKL experts can help you.

[Gennady_F_Intel]

Eric, Could you give us the example to check the problem on our side?