Distributed Shared Memory (DSM)
implements the distributed systems shared memory model in a distributed system, that hasn’t any physically shared memory. Shared model provides a virtual address area shared between any or all nodes. To beat the high forged of communication in distributed system. DSM memo, model provides a virtual address area shared between all nodes. systems move information to the placement of access. Information moves between main memory and secondary memory (within a node) and between main recollections of various nodes. Every Greek deity object is in hand by a node. The initial owner is that the node that created the object. possession will amendment as the object moves from node to node. Once a method accesses information within the shared address space, the mapping manager maps shared memory address to physical memory (local or remote).
DSM permits programs running on separate reasons to share information while not the software engineer having to agitate causation message instead underlying technology can send the messages to stay the DSM consistent between compute. DSM permits programs that wont to treat constant laptop to be simply tailored to control on separate reason. Programs access what seems to them to be traditional memory. Hence, programs that Pine Tree State DSM square measure sometimes shorter and easier to grasp than programs that use message passing. But, DSM isn’t appropriate for all things. Client-server systems square measure typically less suited to DSM, however, a server is also wont to assist in providing DSM practicality for information shared between purchasers.
Architecture of Distributed Shared Memory (DSM) :
The architecture of a Distributed Shared Memory (DSM) system typically consists of several key components that work together to provide the illusion of a shared memory space across distributed nodes. the components of Architecture of Distributed Shared Memory :
1.Nodes: Each node in the distributed system consists of one or more CPUs and a memory unit. These nodes are connected via a high-speed communication network.
2.Memory Mapping Manager Unit: The memory mapping manager routine in each node is responsible for mapping the local memory onto the shared memory space. This involves dividing the shared memory space into blocks and managing the mapping of these blocks to the physical memory of the node.
Caching is employed to reduce operation latency. Each node uses its local memory to cache portions of the shared memory space. The memory mapping manager treats the local memory as a cache for the shared memory space, with memory blocks as the basic unit of caching.
3.Communication Network Unit: This unit facilitates communication between nodes. When a process accesses data in the shared address space, the memory mapping manager maps the shared memory address to physical memory. The communication network unit handles the communication of data between nodes, ensuring that data can be accessed remotely when necessary.
A layer of code, either implemented in the operating system kernel or as a runtime routine, is responsible for managing the mapping between shared memory addresses and physical memory locations.
Each node’s physical memory holds pages of the shared virtual address space. Some pages are local to the node, while others are remote and stored in the memory of other nodes.
In summary, the architecture of a DSM system includes nodes with CPUs and memory, a memory mapping manager responsible for mapping local memory to the shared memory space, caching mechanisms to reduce latency, a communication network unit for inter-node communication, and a mapped layer to manage the mapping between shared memory addresses and physical memory locations.