Comp111  Quiz 2 Review
Quiz 2 Dec 8, 2009  closed book
Name:________________________________
Login:______________
Quiz 2 topics
 Lectures 117.
 Stallings chapters 111 (skip material on Windows)
 Assignments 14.
Please fill in the blanks. Each blank is worth 5 points.
 There are three important statistical distributions
important in modelling operating systems.
The
_________{1}________
distribution models interarrival times for events.
Its cumulative distribution function is
_________{2}________
The
_________{3}________
distribution models service times for
individual processing requests.
These distributions are both
_________{4}________, e.g.,
service times for
_________{5}________
requests do not affect the service time for the next request.
 In Kendall notation, an M/M/infinity queue is one in which
arrival times are _________{6}________,
service times are _________{7}________,
and there are an infinite number of _________{8}________.
 Suppose we have an M/M/1 queue with arrival factor λ and
service factor μ. This queue has a stable behavior if
_________{9}________<1, but
_________{10}________
when
_________{9}________>= 1. (both blank 9's have same answer).
In the latter case, the queue length
_________{11}________ without bound.
 A monitor differs from a semaphore in two ways:
 It does not _________{12}________ signals; uncaught
signals are _________{13}________.
 It is tied (via a programming language) to a specific
_________{14}________. It is not possible to erroniously
utilize a monitor to access a different one.
 A(n) _________{15}________ tells the operating system that
attention is needed for a device or peripheral; a(n)
_________{16}________ tells a process that attention is needed.
The operating system cannot receive a(n)
_________{16}________ any more than a process can handle
a(n)
_________{15}________
 Process memory is naturally divided into
_________{17}________ that contain
_________{18}________, each of which
contains a fixed number of bytes. A typical byte of memory can
be divided into three bit fields including a(n)
_________{17}________ address,
_________{18}________ address,
and word address.

Inverted page tables provide a(n)
_________{19}________ efficient mechanism for memory mapping
than
_________{20}________ page tables, because the number of
pages kept in memory is often far less than the total number of
virtual pages available.