Limit the Number of Cores Used for dgemm

*      Fortran source code is found in dgemm_threading_effect_example.f

      PRINT *, "Finding max number of threads Intel(R) MKL can use for"
      PRINT *, "parallel runs"
      PRINT *, ""
      MAX_THREADS = MKL_GET_MAX_THREADS()

      PRINT 20," Running Intel(R) MKL from 1 to ",MAX_THREADS," threads"
 20   FORMAT(A,I2,A)
      PRINT *, ""
      DO L = 1, MAX_THREADS
        DO I = 1, M
          DO J = 1, N
            C(I,J) = 0.0
          ENDDO
        ENDDO

        PRINT 30, " Requesting Intel(R) MKL to use ",L," thread(s)"
 30     FORMAT(A,I2,A)
        CALL MKL_SET_NUM_THREADS(L)

        PRINT *, "Making the first run of matrix product using "
        PRINT *, "Intel(R) MKL DGEMM subroutine to get stable "
        PRINT *, "run time measurements"
        PRINT *, ""
        CALL DGEMM('N','N',M,N,K,ALPHA,A,M,B,K,BETA,C,M)

        PRINT *, "Measuring performance of matrix product using "
        PRINT 40, " Intel(R) MKL DGEMM subroutine on ",L," thread(s)"
 40     FORMAT(A,I2,A)
        PRINT *, ""
        S_INITIAL = DSECND()
        DO R = 1, LOOP_COUNT
          CALL DGEMM('N','N',M,N,K,ALPHA,A,M,B,K,BETA,C,M)
        END DO
        S_ELAPSED = (DSECND() - S_INITIAL) / LOOP_COUNT

        PRINT *, "== Matrix multiplication using Intel(R) MKL DGEMM =="
        PRINT 50, " == completed at ",S_ELAPSED*1000," milliseconds =="
        PRINT 60, " == using ",L," thread(s) =="
 50     FORMAT(A,F12.5,A)
 60     FORMAT(A,I2,A)
        PRINT *, ""
      END DO