CSCI 315 Exam 2 Review
The questions for exam 2 will be taken from/similar
to/based on the following, and on the homework and lab exercises you've
been assigned. While the emphasis of the exam will be on the materials
since last test (Chapters 8, 9, and 10), many concepts used in
these chapters were introduced in earlier chapters. They can't be
- Identify the following:
- object code
- dynamic linking
- shared library
- backing store
- physical address
- logical address
- contiguous memory allocation
- external fragmentation
- internal fragmentation
- page table
- valid bit
- modify bit (dirty bit)
- reference bit
- virtual memory
- demand paging
page replacement algorithms (FIFO, Optimal, LRU and its approximations)
- working set
- attributes of a file
- In contiguous memory allocation schemes, it is possible to use
first-fit, best-fit, and worst-fit strategies. State a justification
for each of these strategies. Is there one that works better or worse than
the others? Explain your answer.
- In the context of a paging system, what is a logical
address? What is a physical
- Explain how a physical address is determined in a paged system
with a TLB. Be specific about what the values are and how they are
- Consider a paged system where addresses are byte addresses,
and pages consist of 16 4-byte words. If the desired page is in frame
5, and the offset is byte 4 in the frame, what is the corresponding
- In a system with a TLB, assume the following:
Write a formula for computing the effective access time using
- the memory access time is 150 nsec.
- the TLB access time is 25 nsec.
- the TLB hit rate is 80%.
- Give two motivations for going to a virtual memory scheme.
- What is the optimal page replacement algorithm? Why isn't it used
- What do we use in practice to approximate the optimal page
- Given a list of page references (reference string) and a set of
frames, figure out page faults for page replace algorithms FIFO,
- Given a list of page references (reference string) and a window
size, figure out the working set within the given window. NOTE:
this is easy, but I will not ask you to do this on the exam. You should
know what a working set is and how an OS can use the working set sizes to
try to prevent thrashing, but you don't need to know about windows and
ways of approximating the working sets.
- What are some possible ways of organizing a directory system?
- What are the two main types of file access covered in the course text?