Comp111 - Operating Systems

Quiz 2 - Nov 25, 2013 - closed book



Closed book and notes. No electronic devices allowed. Please fill in the blanks. Each blank is worth 5 points. Blanks with the same number have the same answer.

  1. If 20 people per hour arrive at a restaurant, and the same number of people leave every hour on average, and we observe that people stay an average of 2 hours, then there are ________1________ people on average inside the restaurant. This is only true because the system is in ________2________ and because all values are ________3________. If -- in addition -- there are always an average of 5 people waiting in line to be seated inside the restaurant , then the wait for seating is an average of ________4________ hour(s).
  2. Inside an operating system, names are for human use and most entities are identified by ________5________; thus it is convenient to store many kinds of internal entity descriptors in ________6________.
  3. A scheduler is called ________7________ if every process in the run queue receives the same amount of time. In O(1) scheduling, every process gets one time slice per ________8________. This is not considered ________7________ because it does not compensate for time a process spends ________9________ for other events. The ________10________ scheduler gives such processes extra time.
  4. The buddy system guarantees that if one frees and then reallocates the same amount of storage, one will always get the ________11________ memory back. This is because the freed block is linked at the ________12________ of the appropriate free list.
  5. If several processes have the same file open, they all share the same ________13________ descriptor for the file. If every process used a different one to write to the same file, then output could potentially be ________14________.
  6. From the point of view of a process, memory fragmentation of the frame table is called ________15________ fragmentation, while fragmentation due to malloc is called ________16________ fragmentation. From the operating system's point of view, fragmentation of the frame table is ________17________.
  7. Modern memory addressing uses ________18________ to represent sparse maps, and ________19________ to represent dense maps. Segments are utilized to decrease the amount of information one must store about each memory ________20________.
  8. (Extra credit) Determining whether to execute a process is called ________21________ control.