STRUCTURE OF SHARE MEMORY SPACE
Structure defines the abstract view of the shared memory space.
The structure and granularity of a DSM system are closely related three approaches:
· Structuring by data type
· Structuring as a database
1. NO SRTUCTURING:-
Ø The shared memory space is simply a linear array of words.
Ø Choose any suitable page size as the unit of sharing and a fixed grain size may be used for all application.
Ø Simple and easy to design such a DSM system.
2. STRUCTURING BY DATA TYPE:-
Ø The shared memory space is structured either as a collection of variables in the source language.
Ø The granularity in such DSM system is an object or a variable.
Ø DSM system use variable grain size to match the size of the object/variable being accessed by the application.
3. STRUCTURING AS A DATABASE:-
Ø Structure the shared memory like a database.
Ø Shared memory space is ordered as an associative memory called tuple space.
Ø To perform update old data item in the DSM are replaced by new data item.
Ø Processes select tuples by specifying the number of their fields and their values or type.
Ø Access to shared data is non transparent. Most system they are transparent.