Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] MPI - memory sharing?
From: Rohan Deshpande (rohand87_at_[hidden])
Date: 2012-05-17 20:29:04


Yes. thanks :)

On Fri, May 18, 2012 at 7:06 AM, Jeff Squyres <jsquyres_at_[hidden]> wrote:

> MPI 2 does not say anything about memory sharing.
>
> In Open MPI, each MPI process (i.e., each unique rank in MPI_COMM_WORLD)
> will have a completely separate memory space. So the malloc() that you do
> in MCW rank 0 will be totally different than the malloc() that you do in
> MCW rank 1.
>
> Make sense?
>
> On May 16, 2012, at 8:08 AM, Rohan Deshpande wrote:
>
> > I have following structure of MPI code -
> >
> > int main(){
> >
> > MPI_INIT.....
> > //initialize MPI
> > data = malloc(sizeof(int)*200);
> > //initialize data
> > /*--------Master---------*/
> > if(taskid == 0){
> >
> > //send data to each slave
> > MPI_SEND....
> > }
> >
> > /*----Slaves-------*/
> > if(taskid > 0){
> >
> > //accept data from master
> > MPI_RECV....
> > //do some calculations
> > }
> >
> > MPI_Finalize()
> > }
> >
> > I have few doubts about the code above.
> > In above code, the data is allocated memory in the main program. If I
> run this program on cluster where
> > node 1 is slave and node 0 is master, does node 1 actually shares the
> memory location of node 0 to perform the calculations?
> >
> > If I do not want to share the memory, how can i make task on node 1 work
> independently ?
> >
> > Thanks in advance.
> >
> >
> >
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>

-- 
Best Regards,
ROHAN DESHPANDE