commops.h File Reference

#include "../../../shared/Numerics/types.h"
#include "../../../shared/io/Comm/IssmComm.h"
#include "../../mpi/issmmpi.h"

Go to the source code of this file.

Functions
int	DetermineLocalSize (int global_size, ISSM_MPI_Comm comm)
int *	DetermineRowRankFromLocalSize (int global_size, int localsize, ISSM_MPI_Comm comm)
void	GetOwnershipBoundariesFromRange (int *plower_row, int *pupper_row, int range, ISSM_MPI_Comm comm)
int	DetermineGlobalSize (int local_size, ISSM_MPI_Comm comm)

Function Documentation

DetermineLocalSize()

int DetermineLocalSize	(	int	global_size,
		ISSM_MPI_Comm	comm
	)

Definition at line 9 of file DetermineLocalSize.cpp.

                                                          {
 
   /*output: */
   int  local_size;
 
   /*intermediary: */
   int  i;
   int  row_rest;
   int* num_local_rows=NULL;
 
   /*from MPI: */
   int num_procs;
   int my_rank;
 
   /*recover my_rank*/
   ISSM_MPI_Comm_rank(comm,&my_rank);
   ISSM_MPI_Comm_size(comm,&num_procs);
 
   /* TODO replace the following with ->
 
   local_size=global_size/num_procs; // integer division
   if (global_size%num_procs>my_rank) local_size++; // distribute the remainder
   return local_size;
 
   <- to here  */
 
   /*We are  not bound by any library, just use what seems most logical*/
   num_local_rows=xNew<int>(num_procs);    
 
   for (i=0;i<num_procs;i++){
      /*Here, we use floor. We under distribute rows. The rows 
        left  are then redistributed, therefore resulting in a 
        more even distribution.*/
      num_local_rows[i]=(int)floor((double)global_size/(double)num_procs); 
   }
 
   /*There may be some rows left. Distribute evenly.*/ 
   row_rest=global_size - num_procs*(int)floor((double)global_size/(double)num_procs);
   for (i=0;i<row_rest;i++){
      num_local_rows[i]++;
   }
   local_size=num_local_rows[my_rank];
 
   /*free ressources: */
   xDelete<int>(num_local_rows);
 
   /*return size: */
   return local_size;
 
}

DetermineRowRankFromLocalSize()

int* DetermineRowRankFromLocalSize	(	int	global_size,
		int	localsize,
		ISSM_MPI_Comm	comm
	)

Definition at line 12 of file DetermineRowRankFromLocalSize.cpp.

                                                                                    {
 
   /*intermediary: */
   int i,j;
   int my_rank=0;
   int num_procs=0;
   int lower_row,upper_row;
 
   /*output: */
   int* RowRank=NULL;
 
   ISSM_MPI_Comm_rank(comm,&my_rank);
   ISSM_MPI_Comm_size(comm,&num_procs);
 
   /*allocate: */
   RowRank=xNew<int>(global_size);
 
   /*Gather all local_size values into alllocalsizes, for all cpus*/
   int* alllocalsizes=xNew<int>(num_procs);
   ISSM_MPI_Allgather(&localsize,1,ISSM_MPI_INT,alllocalsizes,1,ISSM_MPI_INT,comm);
 
   /*From all localsizes, get lower row and upper row*/
   lower_row=0;
   upper_row=lower_row+alllocalsizes[0];
   for(j=lower_row;j<upper_row;j++)RowRank[j]=0;
 
   for(i=1;i<num_procs;i++){
      lower_row=lower_row+alllocalsizes[i-1];
      upper_row=upper_row+alllocalsizes[i];
      for(j=lower_row;j<upper_row;j++)RowRank[j]=i;
   }
   xDelete<int>(alllocalsizes);
 
   return RowRank;
}

GetOwnershipBoundariesFromRange()

void GetOwnershipBoundariesFromRange	(	int *	plower_row,
		int *	pupper_row,
		int	range,
		ISSM_MPI_Comm	comm
	)

Definition at line 16 of file GetOwnershipBoundariesFromRange.cpp.

                                                                                                  {
 
   /*externals :*/
   int my_rank;
   int num_procs;
 
   /*recover my_rank and num_procs:*/
   ISSM_MPI_Comm_size(comm,&num_procs);
   ISSM_MPI_Comm_rank(comm,&my_rank);
 
   /*output: */
   int lower_row,upper_row;
 
   /*Gather all range values into allranges, for all nodes*/
   int* allranges=xNew<int>(num_procs);
   ISSM_MPI_Allgather(&range,1,ISSM_MPI_INT,allranges,1,ISSM_MPI_INT,comm);
 
   /*From all ranges, get lower row and upper row*/
   lower_row=0;
   upper_row=lower_row+allranges[0];
   for(int i=1;i<=my_rank;i++){
      lower_row=lower_row+allranges[i-1];
      upper_row=upper_row+allranges[i];
   }
 
   /*Assign output*/
   *plower_row=lower_row;
   *pupper_row=upper_row;
   xDelete<int>(allranges);
}

DetermineGlobalSize()

int DetermineGlobalSize	(	int	local_size,
		ISSM_MPI_Comm	comm
	)

Definition at line 10 of file DetermineGlobalSize.cpp.

                                                          {
 
   /*output: */
   int  global_size;
 
   ISSM_MPI_Reduce(&local_size, &global_size, 1, ISSM_MPI_INT, ISSM_MPI_SUM, 0, comm);
   ISSM_MPI_Bcast(&global_size,1,ISSM_MPI_INT,0,comm);
 
   return global_size;
 
}