Editing OpenSSI (section)

===Single IPC space===
OpenSSI provides internode access to all the standard Linux inter-process communication mechanisms, [[Shared memory (interprocess communication)|shared memory]], [[semaphore (programming)|semaphore]]s, [[SYSV]] message queues, [[Named pipe|pipe]]s and [[Unix domain socket]]s.

In order to implement cluster wide shared memory – [[distributed shared memory]] – OpenSSI uses the CFS ''token'' system.  At any one time a memory segment may be readable by one or more nodes, or writable by one node.  If a node without write access to a segment tries to write then the segment is marked unreadable on all other nodes and writable on the current node.  If a node without read access tries to read a segment then the current value is copied from a node where it was valid and if it was writable it is marked readable.