Test 2

Question 1

Linux Memory Area

Answer 1

• a chunk of virtual memory mapped to a VM area space structure

Question 2

task_struct

Answer 2

• The OS stores process state in a data structure called process control block. There is one per process
  called task_struct in linux

Question 3

Difference between segmentation fault and protection fault?

Answer 3

• segmentation fault occurs when request and address is not in the VMA
• protection fault occurs when you don’t have permissions to access that address

Question 4

memory mapping

Answer 4

• structure of data indicating how memory is laid out

Question 5

demand zero page

Answer 5

• physical page fill of 0’s

Question 6

swap file

Answer 6

• same as swap space

- portion of the memory used for virtual memory

Question 7

swap space

Answer 7

• same as a swap file

- portion of the memory used for virtual memory

Question 8

copy on write

Answer 8

• copy file and save new only when wrote to otherwise access the same file

Question 9

demand zero page

Answer 9

• physical page fill with 0’s

Question 10

What does the mmap function do?

Answer 10

• allows you to comb through a file like it is an array

Question 11

What is a dynamic memory allocator and what are the two types of memory allocators?

Answer 11

• memory allocator that all allocate explicitly

- there are two types: explicit and implicit

Question 12

shared object

Answer 12

• a file that contains binary code and data that can be loaded into memory and linked dynamically

Question 13

shared area

Answer 13

• virtual memory that are shared by more than one process and then can be used by multiple programs simultaneously. Although virtual memory allows processes to have separate address spaces, there are times when you need processes to share memory.

Question 14

private object

Answer 14

blank

Question 15

throughput (with respect to memory alloactors)

Answer 15

• how many commands per second

Question 16

aggregate payload

Answer 16

• this is all the payloads added together

Question 17

What are the two types of fragmentation?

Answer 17

• internal and external fragmentation

Question 18

internal fragmentation

Answer 18

• type of fragmentation where the payload is smaller than the block size it is going into

Question 19

external fragmentation

Answer 19

• type of fragmentation where the payload…space cannot be filled
• to explain more the area that is free in the block cannot be filled by the payload

Question 20

What are the two types of memory blocks?

Answer 20

• allocated memory and free memory

Question 21

allocated memory

Answer 21

• allocated memory is memory that is filled

Question 22

free memory

Answer 22

• free memory is memory that is not yet filled and waiting to be filled

Question 23

allocated and free blocks

Answer 23

• allocated blocks are blocks that are used up in the memory while free blocks are block that are waiting to be filled in the memory

Question 24

What are some implementation issues? (just a list for this flash card)

Answer 24

• header, payload, padding, free block organization, block placement, block splitting, block coalescing

Question 25

What does the malloc do when it cannot satisfy memory requests?

Answer 25

- it returns a NULL

Question 26

explicit allocator

Answer 26

- explicit allocators explicitly allocates memory | - frees the space

Question 27

implicit allocator

Answer 27

- implicit allocators explicitly allocates memory | - does not free the space