Making the main memory of acluster of computers look as thoughit is a single memory with a singleaddress space.Then can use shared memoryprogramming techniques.
System scalable Hides the message passing – do not explicitlyspecific sending messages between processesSimple extensions to sequential programmingCan handle complex and large data bases withoutreplication or sending the data to processes
May incur a performance penaltyMust provide for protection against simultaneousaccess to shared dataLittle programmer control over actual messagesbeing generatedPerformance of irregular problems in particular maybe difficult
•Special network interfaces and cache•Modifying the OS Kernel•Adding a software layer between the operatingsystem and the application – most convenientway for teaching purposes
•Page based – using the system’s virtualmemory•Shared variable approach – using routines toaccess shared variables•Object based – shared data within collectionof objects. Access to shared data through objectoriented discipline
• Easy to do• Can sit on top of message-passing software such as MPI