Comp111 - Quiz 2 Review Answers
Dec 8, 2009 - closed book
Please fill in the blanks. Each blank is worth 5 points.
- There are three important statistical distributions
important in modelling operating systems.
distribution models inter-arrival times for events.
Its cumulative distribution function is
distribution models service times for
individual processing requests.
These distributions are both
service times for
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 ____poisson____,
service times are ____exponential____,
and there are an infinite number of ____servers____.
- Suppose we have an M/M/1 queue with arrival factor λ and
service factor μ. This queue has a stable behavior if
____λ/μ____>=1. (both blank 9's have same answer).
In the latter case, the queue length
_______increases____ without bound.
- A monitor differs from a semaphore in two ways:
- It does not ____buffer/queue____ signals; uncaught
signals are ____ignored/dropped____.
- It is bound (via a programming language) to a specific
____data structure____. It is not possible to erroniously
utilize a monitor to access a different one.
- A(n) ____interrupt____ tells the operating system that
attention is needed for a device or peripheral; a(n)
____signal____ tells a process that attention is needed.
The operating system cannot receive a(n)
____signal____ any more than a process can handle
- Process memory is naturally divided into
____segments____ that contain
____pages____, each of which
contains a fixed number of bytes. A typical byte of memory can
be divided into three bit fields including a(n)
and word address.
Inverted page tables provide a(n)
____more____ efficient mechanism for memory mapping
____hierarchical____ page tables, because the number of
pages kept in memory is often far less than the total number of
virtual pages available.