Patent Document ID: 8949577
Application ID: 12789986
Patent Flag: 1

Claim One:
1. An apparatus for performing a deterministic reduction operation in a parallel computer, the parallel computer comprising a plurality of compute nodes, each compute node comprising a plurality of computer processors and a CAU (Collectives Acceleration Unit), the CAU coupling computer processors of compute nodes to one another for data communications in a cluster data communications network, the apparatus comprising a computer processor, a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer program instructions that, when executed by the computer processor, cause the apparatus to carry out the steps of: organizing three or more processors of the parallel computer and a CAU into a highly branched tree topology, wherein the CAU is a root of the highly branched tree topology and each processor in the highly branched tree topology is a direct child of the root CAU; establishing a receive buffer comprising a plurality of receive elements, each receive element associated with one of the processors in the highly branched tree topology and configured to store the associated processor's contribution data; receiving, by the root CAU in any order from the processors in the highly branched tree topology, each processor's contribution data; tracking receipt of each processor's contribution data wherein tracking receipt of each processor's contribution data further comprises maintaining a count of the number of processors from which contribution data has been received; and reducing, by the root CAU, only after receipt of contribution data from all processors in the highly branched tree topology, the contribution data stored in the receive buffer in a predefined order wherein reducing the contribution data stored in the receive buffer in a predefined order further comprises reducing the contribution data only after the count is equal to the number of processors in the highly branched tree topology.