tailieunhanh - Lecture Operating system concepts - Module 16

After studying this chapter, you should be able to: Discuss basic concepts related to concurrency, such as race conditions, OS concerns, and mutual exclusion requirements; understand hardware approaches to supporting mutual exclusion; define and explain semaphores; define and explain monitors. | Module 16: Distributed-System Structures Network-Operating Systems Distributed-Operating Systems Remote Services Robustness Design Issues Operating System Concepts Network-Operating Systems Users are aware of multiplicity of machines. Access to resources of various machines is done explicitly by: Remote logging into the appropriate remote machine. Transferring data from remote machines to local machines, via the File Transfer Protocol (FTP) mechanism. Operating System Concepts Distributed-Operating Systems Users not aware of multiplicity of machines. Access to remote resources similar to access to local resources. Data Migration – transfer data by transferring entire file, or transferring only those portions of the file necessary for the immediate task. Computation Migration – transfer the computation, rather than the data, across the system. Operating System Concepts Distributed-Operating Systems (Cont.) Process Migration – execute an entire process, or parts of it, at different . | Module 16: Distributed-System Structures Network-Operating Systems Distributed-Operating Systems Remote Services Robustness Design Issues Operating System Concepts Network-Operating Systems Users are aware of multiplicity of machines. Access to resources of various machines is done explicitly by: Remote logging into the appropriate remote machine. Transferring data from remote machines to local machines, via the File Transfer Protocol (FTP) mechanism. Operating System Concepts Distributed-Operating Systems Users not aware of multiplicity of machines. Access to remote resources similar to access to local resources. Data Migration – transfer data by transferring entire file, or transferring only those portions of the file necessary for the immediate task. Computation Migration – transfer the computation, rather than the data, across the system. Operating System Concepts Distributed-Operating Systems (Cont.) Process Migration – execute an entire process, or parts of it, at different sites. Load balancing – distribute processes across netowrk to even the workload. Computation speedup – subprocesses can run concurrently on different sites. Hardware preference – process execution may require specialized processor. Software preference – required software may be available at only a particular site. Data access – run process remotely, rather than transfer all data locally. Operating System Concepts Remote Services Requests for access to a remote file are delivered to the server. Access requests are translated to messages for the server, and the server replies are packed as messages and sent back to the user. A common way to achieve this is via the Remote Procedure Call (RPC) paradigm. Messages addressed t an RPC daemon listening to a port on the remote system contain the name of a process to run and the parameters to pass to the process. The process is executed as requested, and any output is sent back to the requester in a separate message. A port is a number included at .