itaps-parallel A question about iMeshP interface functions

[Jason Kraftcheck]

Onkar Sahni wrote:
>> I had assumed that if one had a handle for an entity at all, that the
>> local
>> processor knew enough about that entity to answer such questions (e.g.
>> that
>> it is an interface or ghost entity.)  But I missed several discussions.
>> Are
>> we back to considering entity handles to be globally unique across all
>> processors?
> 
>   If entity-handle is local (on local part/proc.) then one can ask such
> questions (ghost entity etc.), but if entity is not local, i.e,
> remote-handle or remote-copt then it is not valid to ask such questions.
> How do we return reasonable error message/code in this case of
> remote-handle. There are no globally unique entity handles.
> 

What is a "remote handle"?   And are you talking about entity handles or
part handles?

> 
>> It seems to me that the iMeshP_getEntOwnerPart and
>> iMeshP_getEntOwnerPartArr
>> are inherently expensive, and those are the only two for which I see a
>> requirement to return an error if the passed entity is not contained in
>> the
>> partition.  I'm looking at the draft spec Karen sent on July 24th.  Is
>> there
>> a more recent one?
> 
>   I do not see why these will be expensive, at least they are not in FMDB
> implementation.
> 

Presumably if you have some structure that allows for a fast search for the
parts an entity is contained in, then that structure is fairly large, as it
must contain values for every mesh entity.  It is either costly in terms of
memory required or slow.  Either way, it is expensive.

How can the FMDB implementation efficiently search for the part an entity is
contained in while not being able to efficiently determine if the entity is
part of a given partition?  Is it the cost of determining which partition a
part is in that FMDB cannot do efficiently?

- jason