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Subject: Re: [OMPI devel] [RFC] mca_base_select()
From: Ralph Castain (rhc_at_[hidden])
Date: 2008-05-09 10:41:33


I just hit a problem with this logic - should be a minor change.

We have several frameworks where we have components that are only allowed be
selected if the user specifically requests them by stating -mca foo bar.
Because it is possible for there to be no other components that want to be
selected, and because it is permissible for no components to be selected for
that framework, we set bar's priority to be -1.

The new select logic will not allow a negative priority to be selected, even
if the user specifically requested that component.

If we set the priority to be 0, then the system will allow the component to
be automatically selected. This is not allowed as it can lead to bad
behavior.

So what we need the select system to do is say "if someone specified a
specific component, don't worry about the returned priority - just use it"

Josh: could you please modify this?

Thanks!
Ralph

On 5/8/08 7:04 PM, "Pak Lui" <Pak.Lui_at_[hidden]> wrote:

> Thanks very much Josh! Will try it out soon.
>
> Josh Hursey wrote:
>> Sorry about that. I didn't test that type of option. It should be
>> working in r18418. Let me know if you see any more issues.
>>
>> -- Josh
>>
>> On May 8, 2008, at 6:04 PM, Pak Lui wrote:
>>
>>> I think I have a problem but I am not sure. I used to be able to use the
>>> circumflex (^) to switch between the gridengine launcher and the ssh
>>> launchers by doing something like this, e.g. -mca plm ^gridengine, to
>>> exclude some of the components plm (and also in ras). It doesn't seem
>>> like the 'negate' is in mca_base_component anymore. I guess I just have
>>> to spell out which component I want explicitly...
>>>
>>> Josh Hursey wrote:
>>>> This has been committed in r18381
>>>>
>>>> Please let me know if you have any problems with this commit.
>>>>
>>>> Cheers,
>>>> Josh
>>>>
>>>> On May 5, 2008, at 10:41 AM, Josh Hursey wrote:
>>>>
>>>>> Awesome.
>>>>>
>>>>> The branch is updated to the latest trunk head. I encourage folks to
>>>>> check out this repository and make sure that it builds on their
>>>>> system. A normal build of the branch should be enough to find out if
>>>>> there are any cut-n-paste problems (though I tried to be careful,
>>>>> mistakes do happen).
>>>>>
>>>>> I haven't heard any problems so this is looking like it will come in
>>>>> tomorrow after the teleconf. I'll ask again there to see if there are
>>>>> any voices of concern.
>>>>>
>>>>> Cheers,
>>>>> Josh
>>>>>
>>>>> On May 5, 2008, at 9:58 AM, Jeff Squyres wrote:
>>>>>
>>>>>> This all sounds good to me!
>>>>>>
>>>>>> On Apr 29, 2008, at 6:35 PM, Josh Hursey wrote:
>>>>>>
>>>>>>> What: Add mca_base_select() and adjust frameworks & components to
>>>>>>> use
>>>>>>> it.
>>>>>>> Why: Consolidation of code for general goodness.
>>>>>>> Where: https://svn.open-mpi.org/svn/ompi/tmp-public/jjh-mca-play
>>>>>>> When: Code ready now. Documentation ready soon.
>>>>>>> Timeout: May 6, 2008 (After teleconf) [1 week]
>>>>>>>
>>>>>>> Discussion:
>>>>>>> -----------
>>>>>>> For a number of years a few developers have been talking about
>>>>>>> creating a MCA base component selection function. For various
>>>>>>> reasons
>>>>>>> this was never implemented. Recently I decided to give it a try.
>>>>>>>
>>>>>>> A base select function will allow Open MPI to provide completely
>>>>>>> consistent selection behavior for many of its frameworks (18 of 31
>>>>>>> to
>>>>>>> be exact at the moment). The primary goal of this work is to
>>>>>>> improving
>>>>>>> code maintainability through code reuse. Other benefits also result
>>>>>>> such as a slightly smaller memory footprint.
>>>>>>>
>>>>>>> The mca_base_select() function represented the most commonly used
>>>>>>> logic for component selection: Select the one component with the
>>>>>>> highest priority and close all of the not selected components. This
>>>>>>> function can be found at the path below in the branch:
>>>>>>> opal/mca/base/mca_base_components_select.c
>>>>>>>
>>>>>>> To support this I had to formalize a query() function in the
>>>>>>> mca_base_component_t of the form:
>>>>>>> int mca_base_query_component_fn(mca_base_module_t **module, int
>>>>>>> *priority);
>>>>>>>
>>>>>>> This function is specified after the open and close component
>>>>>>> functions in this structure as to allow compatibility with
>>>>>>> frameworks
>>>>>>> that do not use the base selection logic. Frameworks that do *not*
>>>>>>> use
>>>>>>> this function are *not* effected by this commit. However, every
>>>>>>> component in the frameworks that use the mca_base_select function
>>>>>>> must
>>>>>>> adjust their component query function to fit that specified above.
>>>>>>>
>>>>>>> 18 frameworks in Open MPI have been changed. I have updated all of
>>>>>>> the
>>>>>>> components in the 18 frameworks available in the trunk on my branch.
>>>>>>> The effected frameworks are:
>>>>>>> - OPAL Carto
>>>>>>> - OPAL crs
>>>>>>> - OPAL maffinity
>>>>>>> - OPAL memchecker
>>>>>>> - OPAL paffinity
>>>>>>> - ORTE errmgr
>>>>>>> - ORTE ess
>>>>>>> - ORTE Filem
>>>>>>> - ORTE grpcomm
>>>>>>> - ORTE odls
>>>>>>> - ORTE pml
>>>>>>> - ORTE ras
>>>>>>> - ORTE rmaps
>>>>>>> - ORTE routed
>>>>>>> - ORTE snapc
>>>>>>> - OMPI crcp
>>>>>>> - OMPI dpm
>>>>>>> - OMPI pubsub
>>>>>>>
>>>>>>> There was a question of the memory footprint change as a result of
>>>>>>> this commit. I used 'pmap' to determine process memory footprint
>>>>>>> of a
>>>>>>> hello world MPI program. Static and Shared build numbers are below
>>>>>>> along with variations on launching locally and to a single node
>>>>>>> allocated by SLURM. All of this was on Indiana University's Odin
>>>>>>> machine. We compare against the trunk (r18276) representing the last
>>>>>>> SVN sync point of the branch.
>>>>>>>
>>>>>>> Process(shared)| Trunk | Branch | Diff (Improvement)
>>>>>>> ---------------+----------+---------+-------
>>>>>>> mpirun (orted) | 39976K | 36828K | 3148K
>>>>>>> hello (0) | 229288K | 229268K | 20K
>>>>>>> hello (1) | 229288K | 229268K | 20K
>>>>>>> ---------------+----------+---------+-------
>>>>>>> mpirun | 40032K | 37924K | 2108K
>>>>>>> orted | 34720K | 34660K | 60K
>>>>>>> hello (0) | 228404K | 228384K | 20K
>>>>>>> hello (1) | 228404K | 228384K | 20K
>>>>>>>
>>>>>>> Process(static)| Trunk | Branch | Diff (Improvement)
>>>>>>> ---------------+----------+---------+-------
>>>>>>> mpirun (orted) | 21384K | 21372K | 12K
>>>>>>> hello (0) | 194000K | 193980K | 20K
>>>>>>> hello (1) | 194000K | 193980K | 20K
>>>>>>> ---------------+----------+---------+-------
>>>>>>> mpirun | 21384K | 21372K | 12K
>>>>>>> orted | 21208K | 21196K | 12K
>>>>>>> hello (0) | 193116K | 193096K | 20K
>>>>>>> hello (1) | 193116K | 193096K | 20K
>>>>>>>
>>>>>>> As you can see there are some small memory footprint improvements on
>>>>>>> my branch that result from this work. The size of the Open MPI
>>>>>>> project
>>>>>>> shrinks a bit as well. This commit cuts between 3,500 and 2,000
>>>>>>> lines
>>>>>>> of code (depending on how you count) so about a ~1% code shrink.
>>>>>>>
>>>>>>> The branch is stable in all of the testing I have done, but there
>>>>>>> are
>>>>>>> some platforms on which I cannot test. So please give this branch a
>>>>>>> try and let me know if you find any problems.
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Josh
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> devel mailing list
>>>>>>> devel_at_[hidden]
>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>>>
>>>>>> --
>>>>>> Jeff Squyres
>>>>>> Cisco Systems
>>>>>>
>>>>>> _______________________________________________
>>>>>> devel mailing list
>>>>>> devel_at_[hidden]
>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>> _______________________________________________
>>>>> devel mailing list
>>>>> devel_at_[hidden]
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>
>>>> _______________________________________________
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>>>
>>>
>>> --
>>>
>>> - Pak Lui
>>> pak.lui_at_[hidden]
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>
>