CSC 469H1 F ADVANCED OPERATING SYSTEMS 2006 Term Test #2 Solution

CSC 469H1 F ADVANCED OPERATING SYSTEMS 2006 Term Test #2 Solution

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../continued CSC 469H1 F / CSC 2208H1F ADVANCED OPERATING SYSTEMS UNIVERSITY OF TORONTO Fall 2007 Term Test #1 NO AIDS ALLOWED Please PRINT in answering the following requests for information: Family Name: _________________________________ Given Names: _________________________________ Student Number: |_ _ _| |_ _ _| |_ _ _| Login (@cdf): ____________________ Notes to students: 1. This test lasts for 110 minutes and consists of 78 marks. Budget your time accordingly. 2. This test has 7 questions and11 pages (including this one); Check that you have all pages before starting. 3. Write in pen. No pencils. Really, I mean it. 4. Write your answers on this “question and answer” paper, in the spaces provided. Be concise . In general, the amount of space provided is an upper bound on the “size” of answer that is expected. If necessary, use space where available and provide explicit pointers. 5. State your assumptions and show your intermediate work, where appropriate. 6. Do not go beyond here until instructed to do so. Write your student number at the top of each succeeding page once you get going. Question Marks 1 /15 2 /12 3 /12 4 /12 5 /12 6 /6 7 /9 Total /78
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CSC 469H1F / CSC 2208H1F, Fall 2007, Test # 1 Student Number: |_ _ _| |_ _ _| |_ _ _| ../continued 2 1. [15 marks, 3 each] Definitions Define (or explain) the following terms, in the context of this course: a) End-to-end argument Principle for system design that says you should not implement some feature in low-level software if higher level software must be involved to really make the feature correct. Support for the feature at lower levels should be seen as a performance optimization, rather than a correctness criteria. b) Hosted virtual machine Type of virtual machine that provides a complete duplicate of the physical machine by hosting the virtualizing software (i.e. the VMM) as an ordinary process on top of an existing OS installation. An example is VMWare Workstation. c) Signal delivery The point at which a process recognizes the arrival of a signal event (i.e. sees that a signal was posted), and the action taken by the process at this point to handle the signal. d) test-and-test-and-set A type of spinlock that reduces the excess memory traffic of a test-and-set based lock by repeatedly checking if the lock is free using an ordinary read instruction, and only performing the atomic test-and-set when the lock is observed to be free. This allows the lock value to be read from the cache while a thread is spinning. e) Backfilling Enhancement to FCFS parallel job scheduling that allows jobs to move ahead of a blocked job in the scheduler queue to take advantage of CPUs that would otherwise be idle.
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CSC 469H1F / CSC 2208H1F, Fall 2007, Test #1 Student Number: |_ _ _| |_ _ _| |_ _ _| 3 2. [12 marks; 6 each] Structure and Performance Operating system primitives (such as system calls and trap handling) generally require architecture support, however, the performance improvements for these primitives from new hardware rarely match those seen for application code. At the same time, improvements in operating system structure often come at the price of increased overheads for applications with the result that new operating systems are slower than old ones.
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