Cit330 - Exam 2 - Slides

Front 1

process

Back 1

a program or instance of a program running on a computer

Front 2

Three Components of a process

Back 2

Program, Data, State

Front 3

process elements

Back 3

Identifier, Priority, Program Counter, Memory Pointers, I/o status info / Accounting info

Front 4

PCB

Back 4

a data structure in the kernel that controls the process / contains the process elements / allows support for multiple processes / how the operating system moves around

Front 5

states

Back 5

not-running, "ready to execute" / blocked, "waiting for I/O" / dispatcher cannot just select the process that has been in the queue the longest b/c it may be blocked

Front 6

queue

Back 6

First in First out

Front 7

two state model

Back 7

Process may be in one of two states - running or non-running / punch card machines / ENTER > NON-RUNNING > DISPATCH > RUNNING > PAUSE OR EXIT

Front 8

five state model

Back 8

NEW - READY - RUNNING - EXIT - BLOCKED

Front 9

When to switch process

Back 9

TIMESLICE - I/O REQUEST / INTERRUPT / TERMINATION(error or exception or normal completion)

Front 10

context switch

Back 10

every time the processor goes down to a different process queue

Front 11

scheduling

Back 11

Why? - assign processes to be executed / reduced response time / more throughput / processor efficiency goes up

Front 12

response time

Back 12

trade off between response time and throughput / keep at adequate level while getting an optimal amount of work done

Front 13

throughput

Back 13

if it is a server you want to increase throughput / try to get the most work done in a second or hour

Front 14

efficiency

Back 14

getting the most out of your processor

Front 15

priorities

Back 15

the story of Solitaire and the nuclear processor / some processes are more important

Front 16

starvation

Back 16

low priority process that don't get enough time

Front 17

short-term scheduling

Back 17

known as dispatcher / executes most frequently / invoked when an EVENT OCCURS

Front 18

mid-term scheduling

Back 18

"swapping"

Front 19

long-term scheduling

Back 19

when you allow a process to enter into the system / "backups run at night"

Front 20

preemptive

Back 20

can be interupted / a process can timeout / means after each time slice we will use the dispatcher and get the next job

Front 21

arrival and service times

Back 21

the time arrived in the queue / the time it will take the process to start and complete

Front 22

FCFS

Back 22

FIRST COME, FIRST SERVE / each process joins ready queue / NON PREEMPTIVE / bad choice for scheduling

Front 23

round robin

Back 23

divy ups the time for processes / PREEMPTIVE use based on a clock / known as time slicing

Front 24

SPN

Back 24

SHORTEST PROCESS NEXT / NONPREEMPTIVE / process with shortest expected processing time is selected next, short processes jump ahead of longer processes / is non-preemptive process /

Front 25

SRT

Back 25

SHORTEST REMAINING TIME / PREEMPTIVE VERSION of SPN / must estimate processing time / chooses the process with the smallest remaining time whether it is a long job or a short job / possible starvation of longer processes

Front 26

HRRN

Back 26

HIGHEST RESPONSE RATIO / NONPREEMPTIVE / rewards those that have the higher ratio of time waiting plus the expected service times

Front 27

feedback

Back 27

PREEMPTIVE / Penalize jobs that have been running longer / Vista and later use this / Linux uses feedback / assign a base priority to a process

Front 28

fair-share

Back 28

user's application runs as a collection of processes (threads)

Front 29

memory management

Back 29

subdividing memory to accommodate multiple processes

Front 30

relocation

Back 30

programmer does not know where the program will place in memory when it is executed / may be swapped to disk and relocated

Front 31

protection

Back 31

processes should not be able to reference memory locations in another process without permission / must be checked at run time

Front 32

sharing

Back 32

allows several processes to access the same portion of memory

Front 33

fixed partitioning

Back 33

any process whose size is less than or equal to the partition size can be loaded into an available partition

Front 34

internal fragmentation

Back 34

main memory use is inefficient. Any program, no matter how small, occupies an entire partition. This is called internal fragmentation

Front 35

dynamic partitioning

Back 35

partitions are of variable length and number / process is allocated exactly as much memory as required

Front 36

external fragmentation

Back 36

eventually getting holes in memory from dynamic partitioning / the longer a system runs the worse fragmentation gets

Front 37

placement algorithm

Back 37

BEST-FIT worst / FIRST-FIT best / NEXT-FIT medium

Front 38

base register

Back 38

starting address for the process / these registers are set when the process is loaded or when the process is swapped in

Front 39

bounds register

Back 39

ending location for the process / use registers for protection

Front 40

paging

Back 40

partition memory into small equal fixed-size chunks and divide each process into the same size chunks

Front 41

page

Back 41

chunks of a process

Front 42

frame

Back 42

chunks of memory

Front 43

page table

Back 43

operating systems maintain a page table for each process / contains the frame location for each page in the process

Front 44

address resolution

Back 44

the long binary math thing - logical to physical addresses