Operating Systems COS3721 Exam Questions And
Answers 100% Accurate
Which of the following is true of the direct-access method?
A) It is the most common mode of access.
B) It allows programs to read and write records in no particular order.
C) The records of a file are of variable length.
D) It is not an efficient technique for finding and retrieving lots of data efficiently. -
ANSWER B) Programs can read and write its records in any order.
Of the following, which is true of the tree-structured directory structure?
A) Because users are not allowed to create their own subdirectories
B) A user cannot obtain permission for access to another user's files
C) Directories can share subdirectories and files.
D) It is the most common directory structure. - ANSWER D) It is the most common
directory structure.
An acyclic-graph directory structure ____.
A) does not allow the sharing of files.
B) allows the sharing of subdirectories and files.
C) is less complicated than a simple tree-structured directory structure.
D) is less flexible than a simple tree-structured directory structure. - ANSWER B)
allows the sharing of subdirectories and files.
The path name /home/people/os-student/chap10.txt is an example of
A) a relative path name
B) an absolute path name
,C) a relative path name to the current directory of /home
D) an invalid path name - ANSWER B) an absolute path name
The UNIX file system uses which of the following consistency semantics?
A) The writes to an already open file by a user are not immediately visible to other users
who have the file open simultaneously.
B) After a file is closed, changes made to it are visible only in sessions that start later.
C) Users are not allowed to share the pointer of the current location into the file.
D) Writes to an open file by a user are visible immediately to other users that have the
file open at the same time. - ANSWER D) Writes to an open file by a user are visible
immediately to other users that have the file open at the same time.
Which of the following is a fundamental property of an immutable file?
A) The file name may not be reused.
B) The file's contents can be changed.
C) This scheme is difficult to realize in the context of distributed systems
D) Its old name could be reused - ANSWER A) The naming will not reuse this old file
name
The Enhanced Second Chance Algorithm In the enhanced second chance algorithm,
which of the following ordered pairs represents a page that would be the best choice for
replacement?
A) (0,0)
B) (0,1)
C) (1,0)
D) (1,1) - ANSWER A) (0,0)
The _____ allocation algorithm allocates available memory to each process according to
its size.
A) equal
,B) global
C) proportional
D) slab - ANSWER C) proportional
The ____ is the number of entries in the TLB multiplied by the page size.
A) TLB cache
B) page resolution
C) TLB reach
D) hit ratio - ANSWER C) TLB reach
________ allows the parent and child processes to initially share the same pages, but
when either process modifies a page, a copy of the shared page is created.
A) copy-on-write
B) zero-fill-on-demand
C) memory-mapped
D) virtual memory fork - ANSWER A) copy-on-write
_____ is the algorithm implemented on most systems.
A) FIFO
B) Least frequently used
C) Most frequently used
D) LRU - ANSWER D) LRU
_____ occurs when a process spends more time paging than executing.
A) Thrashing
B) Memory-mapping
C) Demand paging
, D) Swapping - ANSWER A) Thrashing
Windows uses a local page replacement policy ____.
A) when a process exceeds its working set minimum
B) when a process exceeds its working set maximum
C) when the system undergoes automatic working set trimming
D) under all circumstances - ANSWER B) when a process exceeds its working set
maximum
Which one of the following is NOT true about Solaris memory management?
A) The scanrate is constant-that is, pages are checked at a constant rate.
B) Pageout runs only when the number of free pages is less than the parameter lotsfree
C) The algorithm used is an approximation of LRU.
D) Pages selected for replacement can be reclaimed before being placed on the free
list. - ANSWER A) The rate at which pages are checked (the scanrate) is constant.
How large a segment will be allocated for a request of 39 Kbytes under the Buddy
system for kernel memory allocation?
A) 39 Kbytes
B) 42 Kbytes
C) 64 Kbytes
D) None of the above - ANSWER C) 64 Kbytes
Which of the following is not a true statement about kernel memory allocation?
A) Slab allocation does not suffer from fragmentation.
B) With the buddy system, adjacent segments can be combined into one larger segment.
C) Because the kernel requests memory of many different sizes, some of which are very
small, the system need not be concerned about wasting memory.
D) The slab allocator allows memory requests to be satisfied very quickly. - ANSWER
Answers 100% Accurate
Which of the following is true of the direct-access method?
A) It is the most common mode of access.
B) It allows programs to read and write records in no particular order.
C) The records of a file are of variable length.
D) It is not an efficient technique for finding and retrieving lots of data efficiently. -
ANSWER B) Programs can read and write its records in any order.
Of the following, which is true of the tree-structured directory structure?
A) Because users are not allowed to create their own subdirectories
B) A user cannot obtain permission for access to another user's files
C) Directories can share subdirectories and files.
D) It is the most common directory structure. - ANSWER D) It is the most common
directory structure.
An acyclic-graph directory structure ____.
A) does not allow the sharing of files.
B) allows the sharing of subdirectories and files.
C) is less complicated than a simple tree-structured directory structure.
D) is less flexible than a simple tree-structured directory structure. - ANSWER B)
allows the sharing of subdirectories and files.
The path name /home/people/os-student/chap10.txt is an example of
A) a relative path name
B) an absolute path name
,C) a relative path name to the current directory of /home
D) an invalid path name - ANSWER B) an absolute path name
The UNIX file system uses which of the following consistency semantics?
A) The writes to an already open file by a user are not immediately visible to other users
who have the file open simultaneously.
B) After a file is closed, changes made to it are visible only in sessions that start later.
C) Users are not allowed to share the pointer of the current location into the file.
D) Writes to an open file by a user are visible immediately to other users that have the
file open at the same time. - ANSWER D) Writes to an open file by a user are visible
immediately to other users that have the file open at the same time.
Which of the following is a fundamental property of an immutable file?
A) The file name may not be reused.
B) The file's contents can be changed.
C) This scheme is difficult to realize in the context of distributed systems
D) Its old name could be reused - ANSWER A) The naming will not reuse this old file
name
The Enhanced Second Chance Algorithm In the enhanced second chance algorithm,
which of the following ordered pairs represents a page that would be the best choice for
replacement?
A) (0,0)
B) (0,1)
C) (1,0)
D) (1,1) - ANSWER A) (0,0)
The _____ allocation algorithm allocates available memory to each process according to
its size.
A) equal
,B) global
C) proportional
D) slab - ANSWER C) proportional
The ____ is the number of entries in the TLB multiplied by the page size.
A) TLB cache
B) page resolution
C) TLB reach
D) hit ratio - ANSWER C) TLB reach
________ allows the parent and child processes to initially share the same pages, but
when either process modifies a page, a copy of the shared page is created.
A) copy-on-write
B) zero-fill-on-demand
C) memory-mapped
D) virtual memory fork - ANSWER A) copy-on-write
_____ is the algorithm implemented on most systems.
A) FIFO
B) Least frequently used
C) Most frequently used
D) LRU - ANSWER D) LRU
_____ occurs when a process spends more time paging than executing.
A) Thrashing
B) Memory-mapping
C) Demand paging
, D) Swapping - ANSWER A) Thrashing
Windows uses a local page replacement policy ____.
A) when a process exceeds its working set minimum
B) when a process exceeds its working set maximum
C) when the system undergoes automatic working set trimming
D) under all circumstances - ANSWER B) when a process exceeds its working set
maximum
Which one of the following is NOT true about Solaris memory management?
A) The scanrate is constant-that is, pages are checked at a constant rate.
B) Pageout runs only when the number of free pages is less than the parameter lotsfree
C) The algorithm used is an approximation of LRU.
D) Pages selected for replacement can be reclaimed before being placed on the free
list. - ANSWER A) The rate at which pages are checked (the scanrate) is constant.
How large a segment will be allocated for a request of 39 Kbytes under the Buddy
system for kernel memory allocation?
A) 39 Kbytes
B) 42 Kbytes
C) 64 Kbytes
D) None of the above - ANSWER C) 64 Kbytes
Which of the following is not a true statement about kernel memory allocation?
A) Slab allocation does not suffer from fragmentation.
B) With the buddy system, adjacent segments can be combined into one larger segment.
C) Because the kernel requests memory of many different sizes, some of which are very
small, the system need not be concerned about wasting memory.
D) The slab allocator allows memory requests to be satisfied very quickly. - ANSWER
