CS3283_quiz_10_2_sol - CS3283 Distributed Systems Mid-term...

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1 CS3283 Distributed Systems Mid-term Test (1 hr 10min) Semester A, 2010/11 Name: ________________________ Student ID: ________ _____ Answer ALL questions. Write your answers on the space provided. (Totally 58 marks) Please ensure that your handwritings are readable and grammatically correct. Otherwise, marks may be deducted. The presentation and organization of your answers will also be counted in marking. Question 1 (6 marks) Complete the following sentences to discuss the two main benefits and costs of distributed systems as comparing with centralized computer systems (1.5 marks each). Benefit 1: It could provide a better performance as the concurrency in execution of processes is higher. Benefit 2: Different resources can be shared as different computing systems, which are managing different resources are connected. Cost 1: A distributed system needs to have a tighter control on security as the computing units are distributed and the system is usually open. Cost 2: A distributed system is usually more complex as it needs to have facilities to provide distribution transparency to hide the physical implementation of the system. Question 2 (10 marks) (i) Briefly explain how protection is provided in a process. How protection can be achieved in a thread? (3 marks) Protection (process) => Protection is provided by the OS. A process cannot access the address space belonging to another process. No direct communication between processes. They can only communicate indirectly through the OS with the using of semaphores/monitor in using shared resources. Protection (thread) => The OS does not provide protection to the threads within the same process. Protection is the responsibility of the programmer in using share resources. (ii) Complete the following table: (4 marks)
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2 Distributed OS Multiproc. Multicomp. Network OS
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This note was uploaded on 01/16/2011 for the course CS CS3283 taught by Professor Kylam during the Spring '10 term at City University of Hong Kong.

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CS3283_quiz_10_2_sol - CS3283 Distributed Systems Mid-term...

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