Hi,
I run them on a cluster of machines when I say processes assigned to multiple machines. It is obvious that the computation cost will be increased if multiple processes running on the same host. But why the communication cost is also increased a lot? Could you please give a detail explaination?
thanks
----- Original Message -----
From: Roberto Pasianot <pasianot_at_[hidden]>
Date: Monday, March 29, 2004 1:25 pm
Subject: Re: LAM: is that possible to reduce the communication cost by assigning processes on the same node
>
> Hi,
>
> This might be a stupid question but anyway : are you running on
> a multiprocessor ?. Otherwise what you get is exactly what should
> be expected.
>
> Bye. Roberto.
>
>
> On Mon, 29 Mar 2004, Ming Wu wrote:
>
> > Hi,
> >
> > I assigned multiple processes on one machine instead of several
> machines.
> > In this way, I expect the communication cost will be reduced
> compared> with assigning them to several machines. However, the
> result is weird.
> > both computation cost and communication cost are increased sharply,
> > especially MPI_Reduce, MPI_Sendrecv. It seems that the
> underlying
> > implementation of lam_mpi doesn't favor multiple processes on
> the same
> > host.
> >
> > Your help will be greatly appreciated.
> >
> > thanks
> >
> > _______________________________________________
> > This list is archived at http://www.lam-mpi.org/MailArchives/lam/
> >
>
> _______________________________________________
> This list is archived at http://www.lam-mpi.org/MailArchives/lam/
>
|
