Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI devel] About Marshalling and Umarshalling
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2012-11-05 10:27:17

On Nov 5, 2012, at 10:13 AM, Ralph Castain wrote:

> We adhere to the MPI standard, so we expect the user in such an instance to define a datatype that reflects the structure they are trying to send. We will then do the voodoo to correctly send that data in a heterogeneous environment, and pass the data back (in the defined datatype) to the user on the remote end. They can then put the various items back into their structure.
> I'm not sure what you mean by an "ideal style language". See the MPI standard or our doc page, for example
> for an explanation of how one defines a datatype.

To expand on that, you might want to see some trivial MPI programs that sent native types around (i.e., no datatype construction required). For example:

Note, too, that MPI implementations (Open MPI included) typically don't "marshall" when they don't have to, meaning that we'll send directly from the user's buffer when possible (e.g., sending contiguous buffers in homogeneous situations).

Jeff Squyres
For corporate legal information go to: