Comp111 - Operating Systems

Quiz 2 - Dec 3, 2014 - 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. Little's laws are based upon the assumption that the system is in ________1________ so that the ________2________ and output of the system occur at the same ________3________ rate. If λ is an arrival rate, then ________4________ represents the corresponding time between arrivals. M/M/1 queues assume in addition that arrivals and processing have ________5________ statistical distributions.
  2. The ________6________ scheduler for linux minimizes computation at the expense of non-optimal ________7________. The main feature of this scheduler is that every process in the run queue gets a constant amount of runtime per ________8________.
  3. In an operating system, ________9________ fragmentation refers to unused space in the memory space of the requesting process, while ________10________ fragmentation refers to unused space outside the requesting process in the operating system.
  4. In a file system, a(n) ________11________ documents the location of a file, while a(n) ________12________ documents its name. In order to create a file one must initialize these and also mark the disk space required as ________13________. This is typically done through the use of ________14________ vectors.
  5. The buddy system guarantees that if one frees and then reallocates the same amount of storage, one will always get the ________15________ memory back when asking again. This is because the freed block is linked at the ________16________ of the appropriate free list.
  6. The fact that multiple processes share the same kernel descriptor for the same file means that output from the processes is appended to the file in ________17________. If multiple processes write to independent kernel descriptors, then the content of the file is determined by the ________18________ process to close it.
  7. The I/O subsystem is a concatenation of multiple producer-consumer systems. For example. in writing to the raw disk, the producer is ________19________, while the consumer is the ________20________.
  8. (Extra credit) The Ext2 filesystem and its derivatives only function properly because of the ________21_________ subsystem for the raw disk device.