Actual source code: PetscMemcpy.c
petsc-3.9.4 2018-09-11
2: #include <petscsys.h>
3: #include <petsctime.h>
5: int main(int argc,char **argv)
6: {
7: PetscLogDouble x,y,z;
8: PetscInt i;
10: PetscScalar *A,*B;
12: PetscInitialize(&argc,&argv,0,0);if (ierr) return ierr;
13: PetscMalloc1(8000000,&A);
14: PetscMalloc1(8000000,&B);
16: for (i=0; i<8000000; i++) {
17: A[i] = i%61897;
18: B[i] = i%61897;
19: }
20: /* To take care of paging effects */
21: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
22: PetscTime(&x);
24: PetscTime(&x);
25: /*
26: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
27: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
28: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
29: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
30: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
31: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
32: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
33: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
34: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000);
35: PetscMemcpy(A,B,sizeof(PetscScalar)*8000000); */
36: { int j;
37: for (j = 0; j<10; j++)
38: for (i=0; i<8000000; i++) B[i] = A[i];}
40: PetscTime(&y);
41: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
42: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
43: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
44: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
45: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
46: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
47: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
48: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
49: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
50: PetscMemcpy(A,B,sizeof(PetscScalar)*0);
51: PetscTime(&z);
53: fprintf(stdout,"%s : \n","PetscMemcpy");
54: fprintf(stdout," %-15s : %e MB/s\n","Bandwidth",10.0*8*8/(y-x));
55: fprintf(stdout," %-15s : %e sec\n","Latency",(z-y)/10.0);
56: fprintf(stdout," %-15s : %e sec\n","Per PetscScalar",(2*y-x-z)/8000000.0);
58: PetscFree(A);
59: PetscFree(B);
60: PetscFinalize();
61: return ierr;
62: }