如何获取MPI中物理机的数量 [英] How to get the number of physical machine in MPI
问题描述
我可以使用 MPI_Comm_size
来获取总处理器数量。
但是我怎样才能得到真正的物理机器的数量?
em>您的意思是一组处理元素,共享一个公共内存地址空间,那么MPI-3分类类型操作 MPI_COMM_SPLIT_TYPE
可以用于可移植地获取这些机器的数量:
int getNodeCount(void)
{
int rank,is_rank0,nodes;
MPI_Comm shmcomm;
MPI_Comm_split_type(MPI_COMM_WORLD,MPI_COMM_TYPE_SHARED,0,
MPI_INFO_NULL,& shmcomm);
MPI_Comm_rank(shmcomm,& rank);
is_rank0 =(rank == 0)? 1:0;
MPI_Allreduce(& is_rank0,& nodes,1,MPI_INT,MPI_SUM,MPI_COMM_WORLD);
MPI_Comm_free(& shmcomm);
返回节点;
$ / code>
在Fortran中:
使用mpi
隐式无
整数,意图(出):: count $($)$ <$ c $> b $ b integer :: shmcomm,rank,is_rank0,ierr
call MPI_COMM_SPLIT_TYPE(MPI_COMM_WORLD,MPI_COMM_TYPE_SHARED,0,&
MPI_INFO_NULL,shmcomm,ierr)
call MPI_COMM_RANK(shmcomm ,rank,ierr)
if(rank == 0)then
is_rank0 = 1
else
is_rank0 = 0
end if
call MPI_ALLREDUCE(is_rank0 ,count,1,MPI_INTEGER,MPI_SUM,&
MPI_COMM_WORLD,ierr)
call MPI_COMM_FREE(shmcomm,ierr)
end subroutine getNodeCount
pre>
该函数首先将世界通信器分成能够创建共享内存区域的队列组,即每个物理机器一个组(给出上述定义)。然后它通过总计0级实体的数量来统计这些组的数量。由于使用集体操作,该功能必须由世界组中的所有级别调用。
免责声明:未经测试的代码 - 使用后风险自负。
I can use MPI_Comm_size
to get the number of total processors.
But how can I get the number of real physical machine?
If by physical machine you mean a set of processing elements, sharing a common memory address space, then the MPI-3 split-by-type operation MPI_COMM_SPLIT_TYPE
could be used to portably obtain the number of such machines:
int getNodeCount(void)
{
int rank, is_rank0, nodes;
MPI_Comm shmcomm;
MPI_Comm_split_type(MPI_COMM_WORLD, MPI_COMM_TYPE_SHARED, 0,
MPI_INFO_NULL, &shmcomm);
MPI_Comm_rank(shmcomm, &rank);
is_rank0 = (rank == 0) ? 1 : 0;
MPI_Allreduce(&is_rank0, &nodes, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
MPI_Comm_free(&shmcomm);
return nodes;
}
And in Fortran:
subroutine getNodeCount(count)
use mpi
implicit none
integer, intent(out) :: count
integer :: shmcomm, rank, is_rank0, ierr
call MPI_COMM_SPLIT_TYPE(MPI_COMM_WORLD, MPI_COMM_TYPE_SHARED, 0, &
MPI_INFO_NULL, shmcomm, ierr)
call MPI_COMM_RANK(shmcomm, rank, ierr)
if (rank == 0) then
is_rank0 = 1
else
is_rank0 = 0
end if
call MPI_ALLREDUCE(is_rank0, count, 1, MPI_INTEGER, MPI_SUM, &
MPI_COMM_WORLD, ierr)
call MPI_COMM_FREE(shmcomm, ierr)
end subroutine getNodeCount
The function first splits the world communicator into groups of ranks capable of creating shared memory regions, i.e. one group per physical machine (give the definition above). It then counts the number of such groups by summing the number of rank-0 entities. Due to the use of collective operations, the function must be called by all ranks in the world group.
Disclaimer: untested code - use at your own risk.
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