Advanced Operating Systems- Distributed Scheduling and shared memory

Advanced Operating Systems- Distributed Scheduling and shared memory

1. Advanced Operating Systems I MCA- II SEMESTER SUBJECT CODE : P22MCACC22 UNIT – III Distributed Scheduling & Shared Memory Presented By S.Vijaya Lakshmi B.E(CSE) Assistant Professor, Department of Computer Science, Sri Sarada Niketan College for Women,Karur .

2. Distributed Scheduling Scheduling refers to the execution of non-interactive processes or tasks (usually called `jobs') at designated times and places around a network of computers (see the Special Topics Guide on Scheduling). Distributed Scheduling refers to the chaining of different jobs into a coordinated workflow that spans several computers. 

3. There are two ways to achieve distributed job scheduling: Centralized dispatch of jobs. Peer to peer signalling with local dispatch of jobs.

4. A dvantages of distributed scheduling The primary benefit of a distributed scheduling system is that it more fault tolerant when compared to a traditional job scheduler. With a traditional scheduling system, the job scheduler is either installed on the execution machine or else communicates with only one execution machine.

5. Importance of Scheduling and Time Management Better Work-Life Balance. Activities like medical appointments, meal planning, family time, and sleep are just as important as our jobs and businesses. Managing Workload. Meeting Deadlines. Steady Progress Towards Your Goals. Accountability . Happier Teams.

6. Distributed Shared Memory A distributed shared memory (DSM) system is a collection of many nodes/computers which are connected through some network and all have their local memories. The DSM system manages the memory across all the nodes. All the nodes/computers transparently interconnect and process .

7. Types of Distributed shared memory On-Chip Memory All the data are stored in the CPU's chip. There is a direct connection between Memory and address lines. The On-Chip Memory DSM is very costly and complicated.

8. Bus-Based Microprocessor The connection between the memory and the CPU is established through a number of parallel wires that acts as a bus. All the computer follows some protocols to access the memory, and an algorithm is implemented to prevent memory access by the systems at the same time. The network traffic is reduced by the cache memory.

9. Ring-based Microprocessor In Ring-based DSM, there is no centralized memory present. All the nodes are connected through some link/network, and accessing of memory is done by the token passing. All the nodes/computers present in the shared area access a single address line in this system

10. Distributed shared memory Message Passing Variables are directly shared Variables are formalized. Less cost of communication More Costs of communication Errors may occur by altering the data by the processes. Private address space is associated with the processes which prevents the occurrence of errors. Processes cannot run simultaneously. Processes may run at the same time. Difference between Message Passing and Distributed shared memory:

11. Advantages of Distributed Shared Memory system: Easy Abstraction - Since the address space is the same, data migration is not an issue for programmers, making it simpler to build than RPC. Easier Potability - Sequential to distributed system migration is made easy by the access protocols employed in DSM. Because they make use of a common programming interface, DSM programmes are portable. Locality of data - Data that is being fetched in large blocks, or data that is close to the memory address being fetched, may be needed in the future.

12. Thank You