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Subject: Re: [OMPI users] How to know which process is running on which core?
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-09-24 08:14:37


On the OMPI SVN trunk, we have an "Open MPI extension" call named OMPI_Affinity_str(). Below is an excerpt from the man page. If this is desirable, we can probably get it into 1.5.1.

-----

NAME
       OMPI_Affinity_str - Obtain prettyprint strings of processor affinity
       information for this process

SYNTAX
C Syntax
       #include <mpi.h>
       #include <mpi-ext.h>

       int OMPI_Affinity_str(char ompi_bound[OMPI_AFFINITY_STRING_MAX],
                             char current_binding[OMPI_AFFINITY_STRING_MAX],
                             char exists[OMPI_AFFINITY_STRING_MAX])

[snip]
OUTPUT PARAMETERS
       ompi_bound
                 A prettyprint string describing what processor(s) Open MPI
                 bound this process to, or a string indicating that Open MPI
                 did not bind this process.

       current_binding
                 A prettyprint string describing what processor(s) this
                 process is currently bound to, or a string indicating that
                 the process is bound to all available processors (and is
                 therefore considered "unbound").

       exists A prettyprint string describing the available sockets and
                 cores on this host.

On Sep 23, 2010, at 11:10 PM, Ralph Castain wrote:

> You mean via an API of some kind? Not through an MPI call, but you can do it (though your code will wind up OMPI-specific). Look at the OMPI source code in opal/mca/paffinity/paffinity.h and you'll see the necessary calls as well as some macros to help parse the results.
>
> Depending upon what version you are using, there may also be a function in opal/mca/paffinity/base/base.h to pretty-print that info for you. I believe it may only be in the developer's trunk right now, or it may have made it into the 1.5.0 release candidate....
>
>
> On Thu, Sep 23, 2010 at 11:24 AM, Fernando Saez <saezfernando_at_[hidden]> wrote:
> Hi all, I'm new in the list. I don't know if this post has been treated before.
>
> My question is:
>
> Is there a way in the OMPI library to report which process is running
> on which core in a SMP system? I need to know processor affinity for optimizations issues.
>
> Regards
>
> Fernando Saez
>
>
>
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-- 
Jeff Squyres
jsquyres_at_[hidden]
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