Actual source code: PetscMemcpy.c

  1: /*$Id: PetscMemcpy.c,v 1.24 2001/08/29 20:59:33 balay Exp $*/

 3:  #include petsc.h

  5: int main(int argc,char **argv)
  6: {
  7:   PetscLogDouble  x,y,z;
  8:   int             i,ierr;
  9:   PetscScalar     *A,*B;

 11:   PetscInitialize(&argc,&argv,0,0);

 13:   PetscMalloc(8000000*sizeof(PetscScalar),&A);
 14:   PetscMalloc(8000000*sizeof(PetscScalar),&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:   PetscGetTime(&x);

 24:   PetscGetTime(&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++) {
 39:       B[i] = A[i];
 40:     }
 41:   }}

 43:   PetscGetTime(&y);
 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:   PetscMemcpy(A,B,sizeof(PetscScalar)*0);
 52:   PetscMemcpy(A,B,sizeof(PetscScalar)*0);
 53:   PetscMemcpy(A,B,sizeof(PetscScalar)*0);
 54:   PetscGetTime(&z);

 56:   fprintf(stdout,"%s : n","PetscMemcpy");
 57:   fprintf(stdout,"    %-15s : %e MB/sn","Bandwidth",10.0*8*8/(y-x));
 58:   fprintf(stdout,"    %-15s : %e secn","Latency",(z-y)/10.0);
 59:   fprintf(stdout,"    %-15s : %e secn","Per PetscScalar",(2*y-x-z)/8000000.0);

 61:   PetscFree(A);
 62:   PetscFree(B);
 63:   PetscFinalize();
 64:   return(0);
 65: }