CMPSCI 377 Operating Systems Fall 2005
Lecture 20: December 01
Lecturer: Emery Berger Scribe: Avery, Harris
Today:
•Distributed Systems
•Page Eviction
•Network Topologies
•Network Communication
•Packets
20.1 Distributed Systems
20.1.1 General Information
•A distributed system is a set of physically separate processors connected by one or more communication
links.
–contains no shared clock or memory.
–this systems are in broad use today.
20.1.2 Parallel vs. Distributed Systems
•Tightly-coupled systems or ”parallel processing”
–Systems share clocks, memory, etc.
–Systems frequent communication
•Loosely-coupled systems or ”distributed computing”
–Each system/processor has its own memory and runs independent of the OS.
–Systems have infrequent communication
20.1.3 Advantages of Distributed Systems
•Resource Sharing
–Resources do not need to be replicated because they are shared.
–Expensive resources can be shared
–Processors present the same environment to users.
20-1
