CSC 469H1 F ADVANCED OPERATING SYSTEMS 2006 Midterm

CSC 469H1 F ADVANCED OPERATING SYSTEMS 2006 Midterm -...

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UNIVERSITY OF TORONTO Fall 2014 Midterm Test Course: CSC 469H1F / CSC 2208H1F Instructor: Angela Demke Brown Duration: 110 minutes Aids allowed: One calculator Student Number: Last (Family) Name(s): First (Given) Name(s): Do not turn this page until you have received the signal to start. (In the meantime, please fill out the identification section above, and read the instructions below carefully .) This midterm test sample solution consists of 8 questions on 12 pages (including this one). If you need more space for one of your solutions, use the last page of the test and indicate clearly the part of your work that should be marked. We have been careful to leave enough space for your answers. In your written answers, be as specific as possible and ex- plain your reasoning. Clear, concise answers will be given higher marks than vague, wordy answers. Please make your handwriting legible! Please write in pen. Answers written in pencil will not be re-graded. Marking Guide Original Total : /78 Adjusted Total : /72 Total Pages = ?? Page 1
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CSC 469H1F / CSC 2208H1F Midterm Test — Solutions Fall 2014 Question 1. Definitions [10 marks] Define the following terms in the context of this course. Part (a) [2 marks] Measurement bias Measuring some effect, such as an optimization O on a system S, in an experimental setup that favours the optimized version over the original, making it appear that the effect is larger than it really is. [Or, aspects of the experimental environment which are unrelated to the phenomenon being tested may have an unexpected effect on the measurement, and the effect may be larger in some systems leading to erroneous conclusions when the measurement is used to compare systems.] Part (b) [2 marks] Sequential consistency Result of any parallel execution is equivalent to a legal serial interleaving of the operations from each thread. [May include mention of things like each thread sees effect of its own operations in program order, and memory operations have some global order across all threads.] Part (c) [2 marks] Layered system Operating system design that separates functionality into layers, each of which has a well-defined function and interface to the layer above or below. [May include mention of layers providing a particular abstraction, as in the THE segment controller abstracting away the physical memory limits via demand paging.] Part (d) [2 marks] Convoying In lock-based parallel programs, particularly where threads have similar amounts of work to do between lock requests, convoying is the tendency for a lock to become contended and to stay that way because any delay (e.g. interrupt) of the lock holder allows other threads to catch up and wait for the lock. [bolded part is essential part of answer, the rest is not required.] Part (e) [2 marks] Symbiotic scheduling In multiprocessor scheduling, when multiple CPUs share a lower-level cache, identifying sets of threads (or processes) that share the cache well and scheduling them together. [Examples not needed, but may
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