Shared Variable Distributed Shared Memory

Page-based DSM takes a normal linear address space and allows the pages to migrate dynamically over the network on demand. A more structured approach is to share only certain variables and data structures that are needed by more than one process. In this way, the problem changes from how to do paging over the network to how to maintain a potentially replicated, distributed data base consisting of the shared variables.

Different techniques are applicable here, and these often lead to major performance improvements. Using shared variables that are individually managed also provides considerable opportunity to eliminate false sharing. If it is possible to update one variable without affecting other variables, then the physical layout of the variables on the pages is less important. The most important example of such system is Munin.


                    
DSM Home   Subway   Shared Mem    Page     Object     
  Page       Map      Systems     Based     Based