On 10-07-16 04:21 PM, Devine, Karen D wrote:
Today's attendees: Carl, Seegyoung, Misbah, Jason, Tim, Vitus, Karen, Mark Beall, Saurabh
In today's iMeshP phone conference, we discussed options that would associate entities with parts during the entities' creation. This association is desirable to provide consistency of the data base for parallel applications and for efficiency in some implementations. And, indeed, for parallel operations to make sense, entities must belong to some part. In addition, we'd like to allow serial iMesh services to be applied to all entities in a part; having a mechanism to add entities to a part during the creation process allows the serial service to be used.
We discussed services that one might like to use in serial within a part. Mesh smoothing was one example; however, because it does not create entities, it is not relevant to this discussion. Other options, like mesh generation and edge swapping, need to have some parallel awareness when they are used in parallel. We envisioned that some serial kernels could be used under a parallel-aware wrapper for these types of services, provided that the serial kernels could add entities to the desired part.
Note that below, I refer to "serial" and "parallel" services. Serial services are those that do not use iMeshP; they view the root set as the entire mesh, with no concept of partitions, part boundaries or ghosts. Parallel services use iMeshP and recognize that the mesh is distributed across one or more processors.
We identified two options:
A. Change the iMesh_createEnt function to include an entity set handle argument PH. For serial applications, PH would be the root set; that is, entities are added only to the root set. For parallel applications, PH would be a part handle; the created entity would be added to the part identified by the part handle. Since iMesh_createEnt is an iMesh function (not an iMeshP function), we would use entity set handle as the argument type, so that serial users would not have to include iMeshP.h nor link with iMeshP. This option was generally accepted by Carl, Simmetrix, Sandia and RPI. Tim is in favor of adding the argument, but does not like the restriction of the handle to be either the root set or a part handle. My fear in allowing arbitrary entity set handles to be used is as follows: if a service uses the entity set handle to, say, add entities to a boundary condition set, that service could not be used in parallel, as its iMesh_createEnt calls would not add the entities to a part.
B. Add a new iMeshP function iMeshP_createEnt that takes as input a part handle. Parallel services would need to use iMeshP_createEnt to add entities, include iMeshP.h, and link with an iMeshP library; iMesh_createEnt would return an error. Serial services would continue to use iMesh_createEnt. This option is more explicit than option A, but requires more work on the user's part if the user wants code to work both with and without iMeshP.
I think this is a pretty accurate description.
One point we didn't discuss but, perhaps, should have was when and how entity ownership should be assigned. The proposed changes add entities to parts, but do not address determining the ownership or copy-status of an entity. I am not sure where these issues should most appropriately be resolved; can they be postponed until iMeshP_syncPartitionAll?
I had assumed that we were talking about setting ownership, since that's the real sticking point: entities that don't have an owner can't be modified (as I interpret the current spec). Carl -- ------------------------------------------------------------------------ Dr. Carl Ollivier-Gooch, P.Eng. Voice: +1-604-822-1854 Professor Fax: +1-604-822-2403 Department of Mechanical Engineering email: [email protected] University of British Columbia http://www.mech.ubc.ca/~cfog Vancouver, BC V6T 1Z4 http://tetra.mech.ubc.ca/ANSLab/ ------------------------------------------------------------------------