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Subject: Re: [OMPI devel] RFC - "system-wide-only" MCA parameters
From: Kenneth Lloyd (kenneth.lloyd_at_[hidden])
Date: 2009-09-04 10:54:32


Ralph, and all,

The Japanese have a term poka-yoke which means "fail-safing". This is an
excellent concept to apply. The term does not mean covering all unintended
consequences of error and omission, though.

If folks are downloading OMPI (or any software) for unauthorized purposes,
that seems a policy problem. If it happens more that once or twice in a
lifetime, or ever in a production environment, it is an indication of a
system run amok.

I'm for a root (sysadmin) privilege for setting mca parameters.

Ken

> -----Original Message-----
> From: devel-bounces_at_[hidden]
> [mailto:devel-bounces_at_[hidden]] On Behalf Of Ralph Castain
> Sent: Friday, September 04, 2009 8:28 AM
> To: Open MPI Developers
> Subject: Re: [OMPI devel] RFC - "system-wide-only" MCA parameters
>
> Just want to make this very clear, since other LANL people
> are on this list.
>
> I am in no way saying that LANL users are ill-intentioned or
> deliberately attempting to circumvent system restrictions.
> See my other note for the most common scenarios that lead to
> this problem and you will see that is the case.
>
> I do not believe this will fully achieve the goal you seek as
> it has been attempted before - it helped, but doesn't fully succeed.
>
> That said, I do not oppose implementing it as it -does- help
> alleviate the problem.
>
> Please also note that - if you are worried about problems
> caused when tuning - it is often the case that combinations
> of param values cause trouble as opposed to the value of a
> single param (e.g., when specifying QP buffer sizes). I'm not
> sure how your proposal will deal with that situation, but I
> leave that to you. :-)
>
> On Sep 4, 2009, at 7:58 AM, Arthur Huillet wrote:
>
> > Hi,
> >
> > Ralph Castain wrote:
> >> Let me point out the obvious since this has plagued us at
> LANL with
> >> regard to this concept. If a user wants to do something different,
> >> all they have to do is download and build their own copy of OMPI.
> > We are well aware of that. It is relatively easy for a user to
> > circumvent the limitation...
> >>
> >> My point here: this concept can help, but it should in no way be
> >> viewed as a solution to the problem you are trying to
> solve. It is at
> >> best a minor obstacle as we made it very simple for a user to
> >> circumvent such measures.
> > ... however the problem we are trying to solve is that some
> users may
> > inadvertantly modify parameters that they should not, for
> example when
> > playing around with MCA parameters in order to "tune"
> > their application.
> > System wide parameters make it possible to give a message
> to the user
> > saying he is not allowed to do what he tried to do, and
> this is a nice
> > to have feature.
> >
> > We are defending the system against users who are not ill-
> > intentioned, but simply do not always know what they are doing when
> > they change parameters. System wide parameters do help in this area.
> >
> > --
> > Greetings, A. Huillet
> >
> > _______________________________________________
> > devel mailing list
> > devel_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/devel
>
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