Homework Problems for CS 3750

Directions for homework submissions

Form and Format

• Everything except source code (including "psuedo-code"): Turn in a hard copy. Put it on the 'counter' in front of me before the beginning of class on the due date. DOUBLE SPACE and make margins of between 1" and 1-1/4" on sides, top and bottom - so I'll have room to write comments. Use a font size from 10 to 14. (I prefer a fixed-width font.)
  
  
• Source code: Turn in neat, compilable code. No more than 70 characters per line. Turn in one hard copy and one e-mail copy. Put the hard copy on the 'counter' in front of me before class starts. Send the e-mail before midnight on the due date. Do not send attachments. Just put the text in-line into the message.
  
  

1. Write 250 words or more describing the interplay between operating system software and the interrupt mechanism. In your writing show that you understand A) how interrupts "drive" the actions of the operating system, and B) how the interrupt mechanism in a modern computing system actually works (what hardware devices do to cause an interrupt and the sequence of events that take place between the time that the currently running program is interrupted and the time that program resumes execution).

1. Using information gleaned from chapters one and two, write 500 words or more describing the important functions and responsibilities of a modern multi-user, time-sharing operating system.
   
   
2. Using information from section 2.7 write 250 words or more describing several different approaches to designing operating system structure. Discuss the advantages and disadvantages of each approach.

1. Write 250 words on the topic of programs and processes. Define what a program is and what a process is. Explain what the differences and similarities are between the two concepts. Explain and/or speculate on what operating system data structures must be employed in order to maintain and preserve a program. Answer the same question for a process. Give attention to similarities and differences regarding the data structures too. Use information distilled from your readings of chapter 3 to help you answer this question, and add whatever else you know that you think will be helpful. (Keep in mind the "intended readership" described in the directions above.)

1. Rewrite the essay you wrote in answer to the question for chapter #03. The directions are the same except that this time you must cover three concepts: program, process, and thread. In addition to adding information about threads, since you know more now you should be able to improve on what you said before about programs and processes.

1. Do problem 5.12 on page 220 (this involves making Gantt charts and calculating measures of the performance of several scheduling algorithms).
   
   
2. Do problem 5.15 on page 221. (The problem starts with: "Consider a system running ten I/O-bound ...")

1. Do the problem in the file hymanProb.html in this directory. Please take note of the example "scenario" described in the problem statement. Make sure that the solution you construct is the same kind of specific and detailed scenario.
   
   
2. A version of the "readers-writers problem" is described in the text in section 6.6.2. Propose a solution to the following variation on that readers-writers problem: readers and writers must be given access to the [database] resource in the order in which they request it. Readers share the resource to the greatest extent possible. Each writer accesses the resource exclusively.
   
   Write up your proposed solution using a format like the one used in figures 6.11 and 6.12 (and the explanation in the text above figure 6.11 of the meaning of the variables). In other words write pseudo code that shows what the shared variables are, pseudo code for writer processes, and pseudo code for reader processes. Also, like the solution shown in figures 6.11 to 6.12, use only semaphores for synchronization. However, note that the problem I am posing for you is different from the one in the text, so naturally you need to try to think of a solution that is different from what's in figures 6.11 and 6.12.
   
   Assumptions:
   
   
   • The total number of readers and writers does not exceed some fixed bound N.
   • You can declare and use as many semaphore variables as you need.
   • The semaphores work as defined in 6.5.2
   • The list S in each semaphore is a FIFO queue.
   
   In addition to enforcing exclusive writes and allowing shared reads, your solution should be starvation free, and satisfy the progress & bounded waiting requirements for solutions to critical section problems. (See section 6.2.)
   
   Note: The degree of difficulty of this problem may be high for you, but give it a try anyway. It's a good problem to think about.

1. Do problem 8.11 on page 352 (It starts "Given five memory partitions ... ").
   • The chapter contains information you will need to know in order to solve this exercise correctly. Read it.
   • Remember the possibility of using holes created by previous allocations,
   • Assume that for each allocation, the first-fit algorithm starts its search again at the beginning of the list.
   
   
2. Do problem 8.13 on page 352 (It starts: "Compare the main memory organization ..."
   
   
3. Do problem 8.20 on page 353 (It starts: "Consider a paging system with the page table stored in memory."
   
   
4. Do problem 8.23 on page 353 (It starts: "Consider the following segment table"

1. Do the following problem. Show all work in detail.
   
   A virtual address of 76543656 (hex) appears in a program that is being run on a computer that does demand paging. The computer has 24-bit physical addresses, 32-bit virtual addresses, and a 1K-word page-size. How many physical frames are there? How many virtual pages are there? What are the page number and the offset corresponding to the virtual address? (Give the last two both in hex notation and decimal notation.)
   
   
2. Do problem 9.21 on pages 412-413 (It starts: "Assume that we have a demand-paged memory. The page table is held in registers. ...").

1. Do problem 10.10 on page 458 ("Consider a file system in which a file can be ...")
   
   
2. Do problem 10.18 on page 459 ("Some systems provide file sharing by ...")

1. Do problem 11.10 on page 500 ("What are the advantages of the variant ...")
   
   
2. Do problem 11.13 on page 501 ("Discuss how performance optimization ...")
   
   
3. Do problem 11.14 on page 501 ("Consider a file system on a disk that has ...")

1. Do problem 12.16 on page 548 ("Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999 ...")
   
   
2. Do problem 12.29 on page 550 ("Discuss the relative advantages and disadvantages ...")
   
   
3. Do problem 12.35 on pages 551-552 ("Suppose that a one-sided 5.25-inch optical-disk cartridge ...")

1. Do problem 13.1 on page 586 ("State three advantages of placing ...")
   
   
2. Do problem 13.5 on page 586 ("How does DMA increase ...")
   
   
3. Do problem 13.6 on page 586 ("Why is it important to scale up ...")

1. Do problem 14.1 on page 616 ("What are the main differences ...")
   
   
2. Do problem 14.9 on page 617 ("Why is it difficult to protect ...")

1. Do problem 15.1 on page 666 ("Buffer overflow attacks ...")
   
   
2. Do problem 15.9 on page 667 ("Make a list of six security concerns ...")
   
   
3. Do problem 15.13 on page 667 ("Why doesn't D(k_e, N)(E(k_d, N)(m)) provide ...")

1. Do problem 16.2 on page 701 ("Under what circumstances is a token ...")
   
   
2. Do problem 16.4 on page 701 ("Discuss the advantages and disadvantages of caching ...")
   
   
3. Do problem 16.11 on page 702 ("Consider a distributed system with two sites ...")

1. Do problem 17.1 on page 724 ("What are the benefits of a DFS ...")
   
   
2. Do problem 17.7 on page 724 ("Compare and contrast the techniques ...") In your answer, be sure to thoroughly discuss the advantages and disadvantages of each technique.
   
   
3. Do problem 17.11 on page 724 ("Describe some of the fundamental differences ...")