Example of Data Alignment

Needs for best performance with Intel® oneAPI Math Kernel Library or for reproducible results from run to run of Intel® oneAPI Math Kernel Library functions require alignment of data arrays. The following example shows how to align an array on 64-byte boundaries. To do this, usemkl_malloc() in place of system provided memory allocators, as shown in the code example below.

Aligning Addresses on 64-byte Boundaries

            
            // ******* C language *******
            ...
            #include <stdlib.h>
            #include <mkl.h>
            ...
            void *darray;
            int workspace;    
            // Set value of alignment
            int alignment=64;
            ...
            // Allocate aligned workspace
            darray = mkl_malloc( sizeof(double)*workspace, alignment );
            ...
            // call the program using oneMKL
            mkl_app( darray );
            ...
            // Free workspace
            mkl_free( darray );

            ! ******* Fortran language *******
            ...
            ! Set value of alignment
            integer    alignment
            parameter (alignment=64)
            ...
            ! Declare oneMKL routines
            #ifdef _IA32
            integer mkl_malloc
            #else
            integer*8 mkl_malloc
            #endif
            external mkl_malloc, mkl_free, mkl_app
            ...
            double precision darray
            pointer (p_wrk,darray(1))
            integer workspace
            ...
            ! Allocate aligned workspace
            p_wrk = mkl_malloc( %val(8*workspace), %val(alignment) )
            ...
            ! call the program using oneMKL
            call mkl_app( darray )
            ...
            ! Free workspace
            call mkl_free(p_wrk)