UPC Collective Communication Working Group

Resolved
• Begin with the Wiebel-Greenberg proposal
  (The current draft document is http://www.gwu.edu/~upc/upcvws/upcws.html)
• Collectives will be type-generic.

Semantic requirements
• The result of a collective operation must be the same as if the operation is surrounded by barriers.
• The collective operations must be implementable in UPC.
• Shared vs. private arguments have yet to be considered.
• The operator list for reduce will consist of predefined operators and it will allow user-provided operators.
• Helper libraries may be provided for operations such as array sectioning.

The deadline for the draft document is May 1, 2002.
• This inital draft document will be based on the Wiebel-Greenberg proposal with the addition of the items mentioned above.

Proposed relocalization collective operations
(See the draft document for details.)
• upc_scatter
• upc_gather
• upc_all_gather
• upc_permute
• upc_all_to_all

Proposed computational collective operations
(See the draft document for details.)
• upc_reduce
• upc_prefix_reduce
• upc_sort

A reference implementation will be prepared to accompany the proposed standard.

Contact Steve Seidel with comments, additions, and corrections for this summary.