Homework Assignment 3

Provide solutions to the following problems.
  1. [10 pts] You are given the following information about a virtual memory system that employs segmentation with paging:
    1. The virtual addresses are of the form <s, p, d>, where s, p and d represent the segment number, page number and displacement within the page, respectively.
    2. The virtual address size is 32 bits.
    3. Page size is 512 bytes.
    Based on these assumptions, answer the following questions.
    1. How many segments are possible if each page table can hold a maximum of 2048 entries? What is the maximum possible size of each segment?
    2. How many segments are possible if each page table can hold a maximum of 8192 entries? What is the maximum possible size of each segment?
  2. [5 pts] Is the open system call in UNIX absolutely essential? What would the consequences be of not having it?
  3. [5 pts] Some operating systems provide a system call rename to give a file a new name. Is there any difference at all between using this call to rename a file, and just copying the file to a new file with the new name, followed by deleting the old one?
  4. [7 pts] Free disk space can be kept track of using a free list or a bitmap. Disk addresses require D bits. For a disk with B blocks, F of which are free, state the condition under which the free list requires less space than the bitmap. For D having the value 16 bits, express your answer as a percentage of the disk space that must be free.
  5. [8 pts] Contemporary computers often have more than 100MB of physical memory. Suppose the page size is 2KB. How many entries would an associative memory need in order to implement a page table for the memory?

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© Mir Farooq Ali 2003.