Set the CNR mode for only one function call

[Guillaume_A_2]

Hi everyone,

I would like to do something like:

... // a lot of stuff with several calls to MKL routines
int cbwrStatus = mkl_cbwr_set(MKL_CBWR_AUTO);
int status = LAPACKE_dsyev( LAPACK_ROW_MAJOR, 'V', 'L', rank, matrix, rank, eigenValues ); 
mkl_cbwr_set(MKL_CBWR_BRANCH_OFF);
... // a lot of stuff with several calls to MKL routines

Here, mkl_cbwr_set calls fail with MKL_CBWR_ERR_MODE_CHANGE_FAILURE, obviously.

So, two questions:

- why is it forbidden (impossible ?) to change the CNR mode after a call to some MKL function ?

- is there a way to set the CNR mode for only one function ?

In my case, "dsyev" is the only function really critical for the reproductibility. I do not want to force the CNR mode at the beginning or before the execution because I am afraid of performance regression.

Thanks in advance for your help,

Guix

[Gennady_F_Intel]

Hi Guix!  Yes, you are right. Into the current version of MKL not possible to set the CNR mode for only one MKL function. That's possible to apply for all mkl's functions. 

[Guillaume_A_2]

Hi Gennady,

Thanks for your reply.

But my questions are "why ?" and "is there a workaround ?" In fact, I am asking for details ;)

Guix