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.
Little's laws are based upon the assumption that the system is in
____balance/equilibrium____ so that the ____input____
and output of the system occur at the same
____average____ rate. If λ is an arrival rate,
then ____1/λ____ represents the corresponding time
between arrivals. M/M/1 queues assume in addition that arrivals and
processing have ____exponential/memoryless____ statistical
The ____O(1)____ scheduler for linux minimizes
computation at the expense of non-optimal
____fairness____. The main feature of this scheduler is
that every process in the run queue gets a constant amount of runtime
In an operating system, ____internal____ fragmentation
refers to unused space in the memory space of the requesting process,
while ____external____ fragmentation refers to unused
space outside the requesting process in the operating system.
In a file system, a(n) ____inode____ documents the
location of a file, while a(n) ____directory____ documents
its name. In order to create a file one must initialize these and
also mark the disk space required as ____used____.
This is typically done through the use of
The buddy system guarantees that if one frees and then reallocates the
same amount of storage, one will always get the
____same____ memory back when asking again. This is
because the freed block is linked at the ____head____
of the appropriate free list.
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 ____time order/sequence____. If multiple processes write to
independent kernel descriptors, then the content of the file is
determined by the ____last/latest____ process to close it.
The I/O subsystem is a concatenation of multiple producer-consumer
systems. For example. in writing to the raw disk, the producer is
____running processes____, while the consumer is the
(Extra credit) The Ext2 filesystem and its derivatives only
function properly because of the ____paging_____
subsystem for the raw disk device.