1. A multiprocessor computer system comprising: a first node including: a first processor; a first local memory coupled to said first processor, wherein a first address space and a second address space are mapped to said first local memory; and a first system interface coupled to said first processor; a second node including: a second processor; a second local memory coupled to said second processor; and a second system interface coupled to said second processor; a global bus coupled to said first system interface and said second system interface; wherein said first address space is configured to store data local to said first node and said second address space is configured to store copies of data local to said second node; and wherein said data stored in said second address space is assigned a physical address local to said first node; and wherein in response to detecting that a local address of a transaction initiated by said first processor corresponds to data which is not local to said first node, said first system interface is configured to convert said local address of said transaction to a global address prior to performing a request corresponding to said transaction on said global bus; and wherein in response to detecting that another local address of another transaction initiated by said first processor corresponds to data local to said first node, said first system interface is configured to perform a corresponding request on said global bus using said another local address without conversion.