Remote node broadcast of requests in a multinode data processing system

Abstract

A data processing system includes first and second coherency domains and employs a snoop-based coherence protocol. In response to receipt by the first coherency domain of a memory access request originating from a master in the second coherency domain, a plurality of coherence participants in the first coherency domain provides partial responses for the memory access request to an early combined response generator. Based on the partial responses, the early combined response generator generates and transmits, to a memory controller of a system memory in the first coherency domain, an early combined response of only the first coherency domain. Based on the early combined response, the memory controller transmits, to the master prior to receipt by the memory controller of a systemwide combined response for the memory access request, data associated with a target memory address and/or coherence permission for the target memory address.