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Subject: Re: [OMPI devel] MCA component open
From: Josh Hursey (jjhursey_at_[hidden])
Date: 2008-05-02 10:37:11

I don't believe we have the logic in place to tell mca_component_open
'do not open anything'. (I could be wrong though).

Adding such an option might be useful, but we would have to consider
how that option should be specified by the user. Currently if you do
not set a value (leave empty space in mca-params.conf) then the MCA
system takes this to indicate that all components are eligible for
selection. If you specify any options then only those options should
be opened. We could add a special keyword (such as 'none') to indicate
'open nothing'.

What do people think about that?

-- Josh

On May 2, 2008, at 10:22 AM, Ralph Castain wrote:

> I see what the problem is. In the case of slurm, I don't want -any-
> components to be opened, even though I am going to call plm open/
> select. I
> have to leave that logic in place for those environments that -do-
> want to
> specify some backend secondary launcher.
> So the question is: how do I tell mca_component_open "do not open
> anything"?
> If we don't have a mechanism for doing that, can we create one?
> On 5/2/08 8:02 AM, "Ralph Castain" <rhc_at_[hidden]> wrote:
>> Well, I have a current version of the trunk. I add an MCA param to
>> the
>> environment indicating that only rsh is to be used by the orted.
>> Yet I get
>> an output from every orted indicating that slurm (misspelled!) is
>> available
>> for selection.
>> This tells me that the slurm component is being opened, even though
>> the
>> param is set.
>> I can check again to ensure that the param is set...
>> On 5/2/08 7:53 AM, "Jeff Squyres" <jsquyres_at_[hidden]> wrote:
>>> (moving to devel list for wider audience)
>>> Hmm. I thought the UTK stuff from a while ago supposedly changed
>>> this
>>> behavior to only open the components that were specifically
>>> requested.
>>> This behavior looks like the *original* MCA behavior -- open them
>>> all,
>>> then discard what we don't want (but doesn't necessarily reclaim the
>>> memory because of how dlclose works).
>>> On May 2, 2008, at 9:48 AM, Ralph Castain wrote:
>>>> Yo guys
>>>> I've noticed something on the trunk that just doesn't strike me as
>>>> correct.
>>>> If I specify "-mca plm rsh", it is my expectation that (a) only the
>>>> rsh
>>>> component will be opened, and (b) only the rsh module will be
>>>> selected,
>>>> unless that component indicates that it cannot run.
>>>> What I am seeing, though, is that -all- the plm components are
>>>> being
>>>> opened.
>>>> This is not only unnecessary, but consumes memory and leads to
>>>> concern over
>>>> whether or not some other module could become active.
>>>> Is this the intended behavior? If so, may I suggest we change it in
>>>> Josh's
>>>> branch prior to bringing it over?
>>>> Ralph
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