Comp111 - Operating Systems

Quiz 2 - Dec 8, 2009 - closed book

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Please fill in the blanks. Each blank is worth 5 points. Blanks with the same number have the same answer.

  1. A device driver is nothing more than a set of ________________1________________ that describe how to ________________2________________ with a device. Each device has a "major number" that serves as an ________________3________________ into a table of drivers.
  2. The disk subsystem and the virtual memory subsystem both use the concept of ________________4________________ things to and from memory, but the disk subsystem uses ________________5________________ memory while the virtual memory subsystem utilizes ________________6________________ memory.
  3. Little's law says that the "average jobs in system" = ________________7________________ times the "average job time in system". It requires only that the input and output rates be ________________8________________ and does not depend upon any statistical properties of processing or job arrival.
  4. A memory page that has been changed since it was read from disk virtual memory is called ________________9________________ and must be ________________10________________ to the disk before the memory can be reused.
  5. Likewise, a block of memory representing a disk block that has changed since it was read from the disk is called ________________9________________ and must be ________________10________________ to the disk before the memory can be reused.

    Name:________________________________

    Login:______________

  6. An M/M/1 queue with arrival rate λ and processing rate μ is only in steady state if ________________11________________ < 1. Both 'M's in the above stand for ________________12________________, which means that a previous arrival time or processing time does not affect the next.
  7. A(n) ________________13________________ of memory is a region of memory that shares the same protection settings, while a(n) ________________14________________ of memory is the smallest amount that can be allocated to a process. A typical memory addressing scheme includes bit fields that represent both of these, as well as the ________________15________________ of the byte or word we want. Because memory maps for processes are sparse, ________________16________________ is often used to locate memory from its address.
  8. A disk file is identified via a(n) ________________17________________ that describes access privileges and where its contents are, but does not contain its ________________18________________, which is instead contained in the directory in which the file resides.
  9. The geometry of a modern disk -- described in terms of cylinders, tracks, and sectors -- is a(n) ________________19________________. The raw disk is a(n) ________________20________________ device, and can only read or write a whole one at a time.