Editing Distributed shared memory (section)

=== Requester-centric request and response ===
In a requester-centric system, the DSM will allow nodes to talk at will to each other through the home. This means that multiple nodes can attempt to start a transaction, but this requires additional considerations to ensure coherence. For example: when one node is processing a block, if it receives a request for that block from another node it will send a NAck (Negative Acknowledgement) to tell the initiator that the processing node can't fulfill that request right away. An example of this is Intel's QPI snoop-source mode.<ref name=":0" /> This approach is fast but it does not naturally prevent race conditions and generates more bus traffic.