Fill-the-blank(s)

Question 1

Mention three file operations: __

Answer 1

Create, Read, Write, Reposition, Delete,
Truncate, Open, Close

Question 2

Mention two required conditions for deadlocks: ___

Answer 2

Mutual Exclusion, Hold and Wait, Non-preemption, Circular Wait

Question 3

The dirty/modified bit in page tables is used to indicate ___

Answer 3

page has been
modified/written to

Question 4

A TLB miss occurs when ___

Answer 4

The required page to frame is not present in the
TLB

Question 5

The Belady’s anomaly occurs when ___

Answer 5

An increased number of frames leads to a
higher page-fault rate

Question 6

File-system metadata (not file metadata) includes the following two items: ___ and ___

Answer 6

inode-free-list, data block free list

Question 7

The main disadvantage of multi-level page tables when compared with flat page
tables is ___

Answer 7

higher page access time during TLB misses

Question 8

Mention two typical operations on directories: ___

Answer 8

Search for file, list directory, Create file, Rename File, Delete file, traverse
file system

Question 9

When succesfull, the return value of fork() in a child process is: ___

Answer 9

zero

Question 10

A trap switches the system from ___ and ___

Answer 10

user, kernel

Question 11

The dirty bit in page tables is used to indicate ___

Answer 11

whether a page has been modified (written to) since it was loaded into memory. ?

Question 12

Mention three operations typically performed in directories ___

Answer 12

add - mkdir or touch

delete - rm or rmdir

list - ls ?

Question 13

In file systems, a hard-link is

Answer 13

A directory entry that associates a file name with an inode ?

Question 14

Directories in file systems are usually implemented using the following two data
structures

Answer 14

Linked lists, hash tables?

maybe b-trees too?

Question 15

Mention two types of file system locks

Answer 15

Advisory Locks, Mandatory Locks ?

Question 16

File system soft-links span

Answer 16

can span across different file systems ?

Question 17

What are the four necessary conditions for a deadlock to occur

Answer 17

1. Mutual Exclusion
2. Hold and Wait
3. No Preemption
4. Circular Wait ?

Question 18

Two POSIX systems calls used for process management are:

Answer 18

fork(), exec() ?

Question 19

The referenced bit in a page table is used to indicate

Answer 19

whether a page has been accessed (read or written to) by the program or process ?

Question 20

File metadata (attributes) includes the following two items

Answer 20

File Size, Timestamps (Creation, Modification, and Access Times) ?

Question 21

The main disadvantage of single-level page tables when compared with multi-level
page tables is

Answer 21

Inefficiency in Memory Usage for Large Address Spaces ?

Question 22

Hard links may span

Answer 22

the same file system ?

Question 23

A TLB hit occurs when

Answer 23

The virtual address being accessed is found in the TLB ?

Question 24

Mention two (POSIX) pthread function calls

Answer 24

pthread_create(), pthread_join() ?

Question 25

Multilevel page tables have the following main advantage over flat page tables

Answer 25

Reduced Memory Usage (Space Efficiency) ?

Question 26

The valid/invalid bit in page tables is used to indicate

Answer 26

whether a page table entry corresponds to a valid, accessible page in physical memory ?

Question 27

A page is

Answer 27

a fixed-size block of virtual memory in a computer system that is managed by the paging memory management scheme. ?

Question 28

A frame is

Answer 28

a fixed-size block of physical memory, which is the unit used to store pages from a program's virtual memory in a paging system ?

Question 29

The dirty bit in a page table is used to indicate

Answer 29

whether a page has been modified (written to) since it was loaded into memory. ?

Question 30

The main advantage of single-level page tables when compared with multi-level page tables is: _____

Answer 30

Simplicity and Faster Lookup ?

Question 31

The TLB contains entries mapping _______________ addresses to ____________ addresses

Answer 31

virtual addresses to physical addresses ?

Question 32

A deadlock avoidance algorithm is

Answer 32

a method used in operating systems to ensure that deadlocks (a situation where two or more processes are blocked forever, waiting for each other to release resources) are prevented from occurring in the system ?

Question 33

Mention three file access APIs in Unix

Answer 33

open(), read(), write() ?

Question 34

A page faults happens when

Answer 34

a process tries to access a page of memory that is not currently in physical RAM ?