Operating Systems Assignments 8-10

A file consists of 4 blocks (0 through 3). File block 0 is mapped to disk block 35. Disk allocation uses contiguous allocation method. Performing "Operation 1. read file block 2" results in _____ disk accesses (reads or writes).

1

A file occupies 4 blocks. Disk allocation uses linked allocation. Performing "Operation 1: read file block 0" results in _____ disk accesses (reads or writes).

1

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the order to serve all the requests, if using FCFS disk-scheduling algorithm?

143→86→1470→913→1774→948→1509→1022→1750→130

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the order to serve all the requests, if using SCAN disk-scheduling algorithm?

143→913→948→1022→1470→1509→1750 →1774 → 4999 → 130 → 86

If we have 36 frames and 4 processes in memory, and use the proportional frame allocation algorithm. Assume that the sizes of processes are: P1 size: 12, P2 size: 8, P3 size: 15, P4 size: 25. If we round the number to the closest integer, the number of frames that P4 will obtain is ____

15

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to serve all the requests, if using SSTF disk-scheduling algorithm?

1745

A file occupies 4 blocks. Disk allocation uses linked allocation. Performing "Operation 2. read file block 2" results in _____ disk accesses (reads or writes).

3

If we have 36 frames and 4 processes in memory, and use the proportional frame allocation algorithm. Assume that the sizes of processes are: P1 size: 12, P2 size: 8, P3 size: 15, P4 size: 25. If we round the number to the closest integer, the number of frames that P2 will obtain is ____

5

If we have 36 frames and 4 processes in memory, and use the proportional frame allocation algorithm. Assume that the sizes of processes are: P1 size: 12, P2 size: 8, P3 size: 15, P4 size: 25. If we round the number to the closest integer, the number of frames that P1 will obtain is ____

7

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to serve all the requests, if using FCFS disk-scheduling algorithm?

7081

Suppose a physical memory system has four frames. Considering the page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6. How many page faults would occur for the Optimal replacement algorithm?

8

For frame allocation algorithm, assume that we have 36 frames and 4 processes in memory. If we use equal frame allocation algorithm, how many frames will each process get?

9

If we have 36 frames and 4 processes in memory, and use the proportional frame allocation algorithm. Assume that the sizes of processes are: P1 size: 12, P2 size: 8, P3 size: 15, P4 size: 25. If we round the number to the smaller integer, the number of frames that P3 will obtain is ____

9

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to serve all the requests, if using SCAN disk-scheduling algorithm?

9769

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to serve all the requests, if using C-SCAN disk-scheduling algorithm?

9985

"Providing the user understanding and control over their data" describes which pillar below?

Transparency and Control

"Only share the approximate location" is one of the new features introduced by iOS 14?

True

Virtual Memory cannot be implemented without demand paging

True

Virtual Memory cannot be implemented without page replacement

True

____ introduced "Limited Photos Library". Users can give apps access to only a limited selection of the photos instead of the entire photos library.

iOS 14

_____ makes it clear to developers and users when apps access pasteboard items from another app, and also warn of apps that may be excessively accessing pasteboard information

iOS 14

When a valid-invalid bit is 1, then the corresponding page resides___

in both physical memory and on disk

p = 0 means the page is currently not resident in memory; p = 1 means the page is currently resident in memory m = 0 means the page has not been modified; m = 1 means the page has been modified A page must be written back to disk when ___

p = 1 and m = 1

"Requesting and only using data that you actually need" describes which pillar below?

Data Minimization

Using _____, Apple server names will automatically resolve DNS queries.

DoH server

Virtual Memory cannot be implemented without the modified bit

False

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the order to serve all the requests, if using SSTF disk-scheduling algorithm?

143→130→86→913→948→1022→1470→1509→1750 →1774

Suppose a physical memory system has four frames. Considering the page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6. How many page faults would occur for the LRU replacement algorithm?

10

A disk with free blocks 2, 5, 6, 9 would be represented with what bit map?

1101100110

A file system uses a bitmap to keep track of free disk space. One bit represents a 512-byte block. The disk contains 2 files, in the order: in the order: A, B, C, with the respective sizes of 1240, 2130, and 600 bytes. Later, file B is deleted, which one below is the correct bitmap?

111000001101...

A file system uses a bitmap to keep track of free disk space. One bit represents a 512-byte block. The disk contains 3 files, in the order: A, B, C, with the respective sizes of 1240, 2130, and 600 bytes. Which one below is the correct bitmap?

111111111101 ...

Suppose a physical memory system has four frames. Considering the page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6. How many page faults would occur for the FIFO replacement algorithm?

14

A disk drive has 5000 cylinders numbered 0 to 4999. The drive is serving a request at cylinder 143 now, and the previous request was at cylinder 125. The queue of pending requests is: 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the order to serve all the requests, if using C-SCAN disk-scheduling algorithm?

143 → 913 → 948 → 1022 → 1470 → 1509 → 1750 → 1774 → 4999 → 0 → 86 →130

Which one of the followings are the fundamental privacy pillars at Apple?

All of the above

When a valid-invalid bit is 0, then the corresponding page resides___

On Disk Only

In ____, users can request approximate location as well as precise location.

On-device Process

A framework ___ can avoid prompting for photos access entirely. It features search and multi-select to help users find what they're looking for and doesn't require the user to grant Photos Library access

PHPicker

"Enforcing the privacy protections on our platform" describes which pillar below?

Security Protections