/Zi makes MKL slow on Windows.

[erling_andersen]

I have a Windows application I build with Intel C 18.0.2 that calls MKL extensively. I want to profile it with Vtune.

If I build it with the /Zi optimization i.e. debug info. needed for profiling it seems to get 5 times slower when run as stand alone from the command line. Vtune tells me that much time is spend in dgemm. Could it add a fixed overhead per dgemm call?

How come? Any suggestions?

Erling

[Gennady_F_Intel]

This is an unexpected case. We expect to see the same mkl performance with and without debug optimization. You may try to measure mkl's ( dgemm in your case ) function performance 

double t1 = dsecnd()

        frot( i=0< m; ++i) dgemm(); 

double t2 = dsecnd() 

and make some conclusion