A cache coherence network for transferring coherence messages between processor caches in a multiprocessor data processing system is provided. The network includes a plurality of processor caches associated with a plurality of processors, and a binary logic tree circuit which can separately adapt each branch of the tree from a broadcast configuration during low levels of coherence traffic to a ring configuration during high levels of coherence traffic. A cache snoop-in input receives coherence messages and a snoop-out output outputs, at the most, one coherence message per current cycle of the network timing. A forward signal on a forward output indicates that the associated cache is outputting a message on snoop-out during the current cycle. A cache outputs received messages in a queue on the snoop-out output, after determining any response message based on the received message. The binary logic tree circuit has a plurality of binary nodes connected in a binary tree structure. Each branch node has a snoop-in, a snoop-out, and a forward connected to each of a next higher level node and two lower level nodes. A forward signal on a forward output indicates that the associated node is outputting a message on snoop-out to the higher node during the current cycle. Each branch ends with multiple connections to a cache at the cache's snoop-in input, snoop-out output, and forward output.

Adaptive scalable cache coherence network for a multiprocessor data processing system

A data structure is described that comprises a balanced binary tree and a binary heap, which may be utilized for combinatorial searching algorithms. For instance, solutions for performing a task, such as a print job or the like, are associated with nodes that are utilized to generate the data structure. Each node is associated with a quality indicator that describes a most optimal solution that may be reached through the node when traversing the binary tree. The binary heap is generated from a subset of the nodes in the tree, wherein each node in the subset has a quality indicator value that is within a predefined range of a best known solution quality. The binary heap is sorted according to a search effort indicator value for each node, where nodes that are more easily reached in the tree are placed higher in the heap to facilitate rapid identification.

Jung Wan Cho

Papers

Directory-based cache coherence scheme using number-balanced binary tree