#include <stdlib.h>

#include "mkl.h"

/* Consider adjusting LOOP_COUNT based on the performance of your computer */

/* to make sure that total run time is at least 1 second */

#define LOOP_COUNT 220 // 220 for more accurate statistics

int main()

{

double alpha, beta;

double s_initial, s_elapsed;

printf("\n This example demonstrates threading impact on computing real matrix product \n"

" C=alpha*A*B+beta*C using Intel(R) MKL function dgemm, where A, B, and C are \n"

" matrices and alpha and beta are double precision scalars \n\n");

m = 2000, p = 200, n = 1000;

printf(" Initializing data for matrix multiplication C=A*B for matrix \n"

" A(%ix%i) and matrix B(%ix%i)\n\n", m, p, p, n);

alpha = 1.0; beta = 0.0;

printf(" Allocating memory for matrices aligned on 64-byte boundary for better \n"

" performance \n\n");

return 1;

}

printf(" Intializing matrix data \n\n");

for (i = 0; i < (m * p); i++) {

A[i] = (double)(i + 1);

}

for (i = 0; i < (p * n); i++) {

B[i] = (double)(-i - 1);

}

for (i = 0; i < (m * n); i++) {

C[i] = 0.0;

}

max_threads = mkl_get_max_threads();

printf(" Finding max number %d of threads Intel(R) MKL can use for parallel runs \n\n", max_threads);

printf(" Running Intel(R) MKL from 1 to %i threads \n\n", max_threads * 2);

for (i = 1; i <= max_threads * 2; i++) {

for (j = 0; j < (m * n); j++)

C[j] = 0.0;

mkl_set_num_threads(i);

cblas_dgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans,

m, n, p, alpha, A, p, B, n, beta, C, n);

s_initial = dsecnd();

for (r = 0; r < LOOP_COUNT; r++) {

}

s_elapsed = (dsecnd() - s_initial) / LOOP_COUNT;

printf(" == Matrix multiplication using Intel(R) MKL dgemm completed ==\n"

" == at %.5f milliseconds using %d thread(s) ==\n\n", (s_elapsed * 1000), i);

}

printf(" Deallocating memory \n\n");

mkl_free(A);

mkl_free(B);

mkl_free(C);

if (s_elapsed < 0.9 / LOOP_COUNT) {

s_elapsed = 1.0 / LOOP_COUNT / s_elapsed;

" of measurements\n\n", i);

}

printf(" Example completed. \n\n");

return 0;

}

==References==

https://www.intel.com/content/www/us/en/developer/articles/technical/a-simple-example-to-measure-the-performance-of-an-intel-mkl-function.html