How to know my code is running on CPU or GPU?

I am a beginner in OpenACC. I want to speed up my program by using OpenACC in fortran language with GCC compiler. my Code is :

Program Test use openacc Implicit None  integer(8)::I1,I2,I3,I4,I5,I6,I,ii,jj,J    !$acc kernels    !$acc loop     do I=1,1200000000     do II=1,300     do jj=1,200     do I1=1,200    do I2=1,500     if(I2==20.and.I1==200.and.JJ==200.and.II==200)then     print*,"Hello"     endif      Data1(I)=I-I+I-I+I      enddo      enddo       enddo        enddo         enddo          !$acc end kernels            end

speed of my code did not change. How can I know my code is running on CPU or GPU?or How I change my code to speed up my program?