In one embodiment, a virtual NUMA system may be formed from multiple
computer systems coupled to a network such as InfiniBand, Ethernet, etc.
Each computer includes one or more software modules which present the
resources of the computers as a virtual NUMA machine. The virtual machine
is a non-uniform memory access (NUMA) machine comprising a plurality of
nodes, each node having memory that is part of a distributed shared
memory. Additionally, the virtual machine is coherent with a weakly
ordered memory model. When executed in a current owner node of a first
block in response to an ownership transfer request from a requesting node
of the plurality of nodes for the first block, the software modules
perform a synchronization operation if the first block has been modified
in the current owner node.