[Forwarding for archival] -------- Original Message -------- Subject: Re: Parallel Interface philosophical comments Date: Tue, 23 Oct 2007 15:09:07 -0400 (EDT) From: Onkar Sahni <[email protected]> To: Devine, Karen D. <[email protected]> CC: Tim Tautges <[email protected]>, Mark Shephard <[email protected]>, Kenneth Jansen <[email protected]>, Ting Xie <[email protected]>, Vitus Leung <[email protected]>, Carl Ollivier-Gooch <[email protected]>, Lori A. Diachin <[email protected]>, Jason Kraftcheck <[email protected]>, Knupp, Patrick <[email protected]> References: <C338DFBB.B5CD%[email protected]> <[email protected]> Hi all, Here are some of my questions and comments on ITAPS parallel interface: 1) Is there a difference between "instance" and "handle" in ITAPS terminology (or are there any definition for these)? (I may have missed it if this was resolved/defined in previous ITAPS interfaces like iMesh). 2) For situations where we want to support multi-parts per processor/process: (a) How do we want to distinguish between processor/process level functionalities against part level ones (keeping user- and implementation-convenience and efficiency in mind)? Ones which would fall under processor level are, like list of parts on processor, MPI_Rank etc., whereas ones which would fall under part level are, like neighboring parts (not procs.) etc. Further, there could be ones where users wants to get/iterate mesh entities (and get adjacencies) at a processor and/or part level. (b) Assuming a part-handle is supported, how can user/application get access to it (say on a processor where part resides)? Basically will there be a way to directly access the part-handle (like part iterator at iProcParts level) or user has to access it through tags/tag names, in which case user has to figure out what is the tag/tag name for a particular part (and who defines these tags/tag names). 3) How general we want to be in interface for different data models/implementations (as in future we may want to incorporate/fit other implementations), especially between serial and parallel data. Two possibilities for data models I can think of are: (a) one (serial) data model is enhanced to store parallel information and (b) serial one is supplemented by a separate parallel one to support parallel functionalities (in possibility (b) all parallel-specific information is stored in a separate data to serial-specific data). We could design interface that would fit both possibilities, this is the reason why we included iPartMesh (section 3.4) level functions which are specific to parallel functionalities in mesh (and passing handle to serial data in these interface will not work for second possibility (b)). I do not know how much relevant is this. Let me know if you have questions. Vitus, due to above questions I did not respond to your comments. I do not know if above questions and comments make things clear. If you still have anything specific please let us know. Karen, Is there a way to create an email list for this subcommittee as if we want to add (and remove) people (and it will keep record of all the messages). I have added Ting in this response as she is also working on this stuff from RPI side. Thanks, Onkar

Hi all, I'd like to re-iterate what I think should be the general behavior of functions in the parallel interface. IMO, we should take advantage of the simple yet powerful data model we already have for iMesh. That means using mesh sets for things which are obviously sets, and using the functions which already exist for accessing data in those sets. I think it does make sense in certain cases to make convenience functions in the parallel interface for accessing e.g. all the sets which represent parts of a partition, on a current processor or globally, but I think we should minimize these. Based on the general behavior described above, I think many of the functions proposed for global ids and parts/partitions already exist in iMesh. For example, iPart_getGlobalID, iPart_createGlobalID, iProcParts_getPartIdArrOnProc, iProcParts iterator functions, etc.

- tim

-- ================================================================ "You will keep in perfect peace him whose mind is steadfast, because he trusts in you." Isaiah 26:3

Tim Tautges Argonne National Laboratory ([email protected]) (telecommuting from UW-Madison) phone: (608) 263-8485 1500 Engineering Dr. fax: (608) 263-4499 Madison, WI 53706

-- ================================================================ "You will keep in perfect peace him whose mind is steadfast, because he trusts in you." Isaiah 26:3 Tim Tautges Argonne National Laboratory ([email protected]) (telecommuting from UW-Madison) phone: (608) 263-8485 1500 Engineering Dr. fax: (608) 263-4499 Madison, WI 53706