there is a weird behavior from mkl on our cluster. I am calling Eigen::SelfAdjointEigenSolverEigen::MatrixXcd for a complex hermitian matrix (ZHEEV).
When I calculate the eigenvectors for large matrices (dim >~ 100k) it only uses a single core.
Strangely, it runs perfectly fine (multiple cores) for smaller complex matrices, real matrices and large complex matrices (dim >~ 100k) without eigenvectors.
Did anyone face the same issue or has any idea what is going on in the background?
I tried various mkl versions.