Operating systems

Question 1

Internal Fragmentation

Answer 1

Little time slots remaining when you insert process into time slot, SOLUTION to it is Compaction(but it’s unfeasable since it takes a while)

Question 2

Remember SJF

Answer 2

if time remaining == burst time of new process, keep current process

Question 3

Remember Round Robin

Answer 3

It gets added onto the end, remember that if only one process remains keep adding lines to gnatt chart since it’s still preempted

Question 4

Turnaround Time and Waiting time

Answer 4

TA = CT - AT
Waiting = TA - BT

Question 5

Multilevel queue

Answer 5

classifies processes and gives priorities based on tht (ex: foreground > background priority), Partitions into a number of ready queues, Processes permanently assigned to one queue.

Question 6

Multillevel feedback queues

Answer 6

Processes can move between queues(unlike multilevel queues) Separates processes according to their CPU bursts too much CPU time for a process should move it to a lower priority queue

Question 7

Starvation

Answer 7

indefinite b locking of process, applies to priority.

Question 8

Remember Context switching

Answer 8

Takes time too

Question 9

Multiprocessor

Answer 9

Share load of procsses,

Question 10

Symmetric Multiprocessing

Answer 10

each processor is self scheduling, can have common ready queue for processors or multiple ready queues for each processor.
Problems: must ensure processors dont choose same processses, and that they aren’t lost from the queue.

Question 11

asymmetric multiprocessing

Answer 11

one processor handles all scheduling decisions, I/O processing and other activities, while other processors handle only user code.

Question 12

Processors & registers

Answer 12

contain registers, have access to main memory on-line memory, RAM. CPU registers use clock cycles, main memory depends on rate of memory bus.

Question 13

Cache

Answer 13

Fast memory buffer, recently used data, checked there first, if not brought in from main.

Question 14

Important process

Answer 14

Hard Disk -> Main Memory -> Cache -> CPU registers

Question 15

Fixed-Size partitioning

Answer 15

allocating memory in multiprogramming system in fixed sized units. Only one process per partition. fixed upper bound

Question 16

Variable partitions & holes & table

Answer 16

There’s table with available places in memory, holes are empty blocks, added to memory via input queue, takes into accoutn size to place processes into memory holes.