Patent ID: 7752281
Filing Date: 2010-07-06
Classification: G06F

Abstract:
1. A system for managing coherent data access through multiple nodes, comprising: a first data processing system forming a first node, in which the first data processing system includes a first processor, a first bridge, a first interface and a first memory that is local to the first node, wherein the first node supports packet traffic for transfer of packets, coherent traffic to access the first memory and non-coherent traffic to communicate with input/output (I/O) circuitry, in which the first memory stores first cacheable data having global coherency; and a second data processing system forming a second node that also supports packet traffic, coherent traffic and non-coherent traffic, in which the second data processing system includes a second processor, a second bridge, a second interface and a second memory that is local to the second node, the second memory storing second cacheable data also having global coherency, the first and second interfaces coupling the first node to the second node via a bi-directional bus for transfer of packet traffic, coherent traffic and non-coherent traffic between the first and second nodes, wherein when the second node receives a data packet from an external source that is to access a cache coherent fabric of the first memory, the second bridge identifies the first memory as located in the first node and generates to an uncacheable data access request to the first node for the data packet instead of performing a cache coherent memory access operation to access the first memory from the second node, so that the access to the first memory does not access a coherent fabric of the second memory in the second node, and when the first bridge receives the uncacheable data access request, the first bridge identifies the uncacheable data access request as a local access request to the first memory in the first node and processes the uncacheable data access request from the second node as a coherent data access request in the first node to access the coherent fabric of the first memory in the first node.