Final Exam Practice代写 operating system代写 virtual memory代写

CSCI 3753: Operating Systems

Final Exam Practice代写 Answer all questions in the space provided1.(20 pt) Mark each term with the letter of the best definition

Fall 2018

Name:  

SID:  

Final Exam Practice Final Exam Practice代写

12/19/2018

Answer all questions in the space provided

1.(20 pt) Mark each term with the letter of the best definition

A.occurs when the operating system cannot find the data in virtualmemory

B.maintaining blocks that are not allocated to some file ordirectory

C.a range of addresses from the perspective of theOS Final Exam Practice代写

D.bit indicating the block needs to be written before beingreplaced

E.a bit to ensure that the total numberof set bits in a block is even or odd

F.allocate the same number foreach process

G.process of identifying that an intrusion has been attempted, is occurring, orhas occurred

H.a fixed size block in physicalmemory space Final Exam Practice代写

I.the ability to accommodate a single or multiple failure and still remain available

J.a reference to another file ordirectory

K.a location in the hierarchy ofdirectories at which to access another file system

L.paging for virtual memorymanagement to decide which memory pages to page out

M.a range of addresses fromthe perspective of a process

N.bit(s) used in reconstruction ofthe original data

O.a fixed size block in logicalmemory spaceFinal Exam Practice代写

P.having the same data stored onseparate storage device hardware

Q.bit indicating that the informationis currently in memory

R.managing on-disk data structuresfor files or directories

S.allocate according to the size ofprocess

T.monitoring and scanning to find unauthorized and possiblymalicious software

logical address space	dirty bit	frame	proportional frame allocation	page replacement
disk redundancy	attack detection	parity	symbolic link	free space management

2.[20 Points] Multiple Choice: Select the best answer for eachquestionFinal Exam Practice代写

A.What is the advantage of storing blocks of a file near each other on thedisk?

1. maximize blockusage
2. parallelize datatransfer
3. minimize seektime
4. serializetransfer

B.If each index block holds 64 (2^6) entries, how many blocks can double indexing accessfor each file?

1. 64 (2^6)
2.   128(2^7)
3.   512(2^9)
4. 4096 (2^12)Final Exam Practice代写

C.Mounting a filesystem:

1. can be used to bypass accessrules
2. can occur anywhere in the directorytree
3. must occur at the root of the directorytree
4. must occur at a leaf in the directorytree

D.Log based transaction methods referto:

1. checkpoints and checksums before diskoperations
2. creation of log for uncommitted modifications
3. disk operations that are performedsynchronously
4. writing log entries for diskerrors

E.Changing the block size from 4K to 8Kwill:Final Exam Practice代写

1. decrease the externalfragmentation
2. decrease the internalfragmentation
3. increase the externalfragmentation
4. increase the internalfragmentation

F.An attempt to make a computer resource unavailable to its intended uses iscalled:

1. hijack
2. denial-of-serviceattack
3. trapdoorbreach
4. man-in-the-middleattack

G.Which of the following makes sure that data is not changed when it is not suppose tobe?

1. confidentiality
2. integrity
3. availability
4. accountability

H.What is the process of identifying anindividual?Final Exam Practice代写

1. authentication
2. authorization
3. confidentiality
4. non-repudiation

I.What is the process that prevents someone from denying that they accessed aresource?

1. authentication
2. authorization
3. confidentiality
4. non-repudiation

3.[20 Points] Multiple Choice: Select ALL that are true for eachquestion

A.Which object types does the VFSdefine?

i.inodeobject

ii.fileobject

iii.superblockobject

iv.dentryobject

v.deviceobject

B.Advantages of distributed systems include:Final Exam Practice代写

i.Resourcesharing

ii.Cryptography

iii.Computationalspeedup

iv.Reliability

v.Security

vi.Communication

C.For paging, every address generated by the CPU is divided into:

i.Fileindex

ii.Pagenumber

iii.Pageoffset

iv.Pagesize

D.Which of the following are replacement algorithms forpaging?

i.FCFS

ii.LRU

iii.SSTF

iv.TCP

v.FIFO

4.[10 Points] Given five named free memory blocks (inorder):Final Exam Practice代写

F1: 100 K, F2: 420 K, F3: 200 K, F4: 295 K, F5: 500 K

And the following space requests (in order of request):

202 K, 417 K, 118 K, 426 K, 90 K

Mark the free memory block location where the requested block will be placed using the given policy.  If the request cannot be satisfied, draw a line through all blocks for that request.

Example with requests of 200K, 300K, 600K

Blocks: 250K, 400K, 500K

best fit	F1	F2	F3
200K	X
400K			X
600K	—-	—–	—–

best fit	F1	F2	F3	F4	F5
202K			Final Exam Practice代写
417K
118K
426K
90K

worst fit	F1	F2	F3	F4	F5
202K
417K
118K			Final Exam Practice代写
426K
90K

5.[10 Points] Given that the page table has 3 frames that are initially empty and the following page referencesequence:

2, 3, 4, 8, 2, 4, 8, 2, 6, 1, 7, 5

What does the page table look like after each page reference and what is the total number of page faults when using each of the page replacement algorithms below.

OPT

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Step 8

Step 9

Step 10

Step 11

Step 12

# page faults

1

Final Exam Practice代写

2

3

FIFO

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Step 8

Step 9

Step 10

Step 11

Step 12

# page faults

1

2

Final Exam Practice代写

3

Least Recently Used

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Step 8

Step 9

Step 10

Step 11

Step 12

# page faults

1

2

Final Exam Practice代写

3

1 6. [10 Points] Given that there are 400 cylinders (0-399)

and the R/W head is on cylinder 201 moving towards lower numbered cylinders, calculate the total distance (# of cylinders) travelled by the R/W head using each of the given disk scheduling methods. The following requests have been received in the following order:

232, 112, 199, 322, 0, 42, 322, 86

what does the sequence of tracks look like when using each of the algorithms below. Note: you may not need to use all the columns.

SSTF	1		2		3		4		5		6		7		8		9		10
cylinder number	2 0 1	→		→		→		→		→		→		→		→		→
total distance travelled   write equation	Final Exam Practice代写

SCAN	1		2		3		4		5		6		7		8		9		10
cylinder number	2 0 1	→		→		→		→		→		→		→		→		→
total distance travelled   write equation

7.[50 Points] Short answerFinal Exam Practice代写

A.What are the problems illustrated in the image below?

*NOTE: Contiguous blue boxes represent an entire process.

What is/are solutions to the problems identified above?

B.What are the advantages/disadvantages for the following disk scheduling algorithms: FCFS, SSTF, SCAN, C-SCAN, LOOK, C-LOOK?

C.How is a child process’s address space initialized after a fork() command is executed in a page sharingscheme?Final Exam Practice代写

D.You are asked to allocate a file according to the multi-level indexed allocation (UNIX inode – triply indirect). Assume that the memory block pointers to support a file containing 200K bytes of data. There are 1 KB per disk block, an index block holds 64 entries, and there are 12 direct pointers in the inode. Fill in the details of how many disk blocks are allocated for this file (NOT including the inodeitself).

1. # blocks in direct blocks=  
2. # blocks in single indirect=  
3. # blocks in double indirect=  
4. # blocks in triple indirect=  
5. # metadata blocks=  

E.What is the type of Redundant Arrays of Inexpensive Disks (RAID) illustrated in the below figure.

a.RAID0

b.RAID1

c.RAID2

d.RAID3

e.RAID4

RAID 0 has worst  over RAID 5.Final Exam Practice代写

a.Storageutilization

b.Faulttolerance

c.Writingspeed

8.[10 Points] Let’s look at the simple MMU that handles logical address to physical address translation using base and limit.

Select the correct labels corresponding to their numbered annotation.Final Exam Practice代写

1	2	3	4
5	6	7	8

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