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Subject: Re: [OMPI devel] problem in the ORTE notifier framework
From: Nadia Derbey (Nadia.Derbey_at_[hidden])
Date: 2009-05-28 03:36:38


On Tue, 2009-05-26 at 17:24 -0600, Ralph Castain wrote:
> First, to answer Nadia's question: you will find that the init
> function for the module is already called when it is selected - see
> the code in orte/mca/base/notifier_base_select.c, lines 72-76 (in the
> trunk.

Strange? Our repository is a clone of the trunk?
>
It's true that if I "hg update" to v1.3 I see that the fix is there.

Regards,
Nadia

> It would be a good idea to tie into the sos work to avoid conflicts
> when it all gets merged back together, assuming that isn't a big
> problem for you.
>
> As for Jeff's suggestion: dealing with the performance hit problem is
> why I suggested ORTE_NOTIFIER_VERBOSE, modeled after the
> OPAL_OUTPUT_VERBOSE model. The idea was to compile it in -only- when
> the system is built for it - maybe using a --with-notifier-verbose
> configuration option. Frankly, some organizations would happily pay a
> small performance penalty for the benefits.
>
> I would personally recommend that the notifier framework keep the
> stats so things can be compact and self-contained. We still get
> atomicity by allowing each framework/component/whatever specify the
> threshold. Creating yet another system to do nothing more than track
> error/warning frequencies to decide whether or not to notify seems
> wasteful.
>
> Perhaps worth a phone call to decide path forward?
>
>
> On Tue, May 26, 2009 at 1:06 PM, Jeff Squyres <jsquyres_at_[hidden]>
> wrote:
> Nadia --
>
> Sorry I didn't get to jump in on the other thread earlier.
>
> We have made considerable changes to the notifier framework in
> a branch to better support "SOS" functionality:
>
>
> https://www.open-mpi.org/hg/auth/hgwebdir.cgi/jsquyres/opal-sos
>
> Cisco and Indiana U. have been working on this branch for a
> while. A description of the SOS stuff is here:
>
> https://svn.open-mpi.org/trac/ompi/wiki/ErrorMessages
>
> As for setting up an external web server with hg, don't bother
> -- just get an account at bitbucket.org. They're free and
> allow you to host hg repositories there. I've used bitbucket
> to collaborate on code before it hits OMPI's SVN trunk with
> both internal and external OMPI developers.
>
> We can certainly move the opal-sos repo to bitbucket (or
> branch again off opal-sos to bitbucket -- whatever makes more
> sense) to facilitate collaborating with you.
>
> Back on topic...
>
> I'd actually suggest a combination of what has been discussed
> in the other thread. The notifier can be the mechanism that
> actually sends the output message, but it doesn't have to be
> the mechanism that tracks the stats and decides when to output
> a message. That can be separate logic, and therefore be more
> fine-grained (and potentially even specific to the MPI layer).
>
> The Big Question will how to do this with zero performance
> impact when it is not being used. This has always been the
> difficult issue when trying to implement any kind of
> monitoring inside the core OMPI performance-sensitive paths.
> Even adding individual branches has met with resistance (in
> performance-critical code paths)...
>
>
>
>
>
> On May 26, 2009, at 10:59 AM, Nadia Derbey wrote:
>
>
>
> Hi,
>
> While having a look at the notifier framework under
> orte, I noticed that
> the way it is written, the init routine for the
> selected module cannot
> be called.
>
> Attached is a small patch that fixes this issue.
>
> Regards,
> Nadia
>
>
> <orte_notifier_fix_select.patch><ATT14046023.txt>
>
>
> --
> Jeff Squyres
> Cisco Systems
>
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-- 
Nadia Derbey <Nadia.Derbey_at_[hidden]>