chapter 3 processes

Question 1

what is the process and its parts ?

Answer 1

a process is a program in execution.
its part : - text section which also called a program code.

• data section which have global variables
• stack: which containing a temporary data.
• current activity : which contains processor registers and counters
• heap : containing memory dynamically allocated during run time.

Question 2

how a program becomes a process ?

Answer 2

when executable file loaded into memory.

it started when clicking a command line entry of its name.

Question 3

what are the states of the process ?

Answer 3

• new : being created
• running : instructions are being executed
• waiting : the process waiting for event to occur.
• ready : the process is assigned to a processor .
• terminated : the process has finished the execution.

Question 4

what information associated with the process ?

Answer 4

• process state
• program counter
• CPU registers
• CPU scheduling
• memory management information
• I/O status information
• accounting information

Question 5

What is the process scheduler job?

Answer 5

It selects process among available processes for next execution.

Question 6

what are scheduling queues ?

Answer 6

• job queues : set of all processes in the system
• ready queue : set of all processes residing in main memory, ready and waiting to execute.
• Device queues : set of all processes waiting for an I/o device.

Question 7

what are scheduler types?

Answer 7

• short term scheduler : selects which processes should be executed next.
• long term scheduler : selects which processes should be brought into ready queue.

Question 8

what types of processes?

Answer 8

• I/O bound process : spends more time doing I/O than computations, many short CPU bursts.
• CPU bound process : spends more time doing computations, few very long CPU bursts.

Question 9

what is swapping ?

Answer 9

Remove process from memory, store on disk, bring back in from disk to continue execution

Question 10

what does context switch do ?

Answer 10

When CPU switches to another process, the system must save the state of the old process and load the saved state for the new process via a context switch.

Question 11

what does context time dependent on ?

Answer 11

context switch time are highly dependent on hardware.

Question 12

what is identifying and managing the process ?

Answer 12

process identifier ( PID)

Question 13

what are process resources sharing options ?

Answer 13

Parent and children share all resources .

Children share subset of parent’s resources.

Parent and child share no resources.

Question 14

what are the process execution options ?

Answer 14

Parent and children execute at the same time.

Parent waits until children terminate.

Question 15

what does exit() do ?

Answer 15

asks the OS to delete it.

Question 16

what does wait() do ?

Answer 16

returns status data to the parent from the child.

Question 17

what does abort() do ?

Answer 17

it is used by parent to terminate the execution of the children.

Question 18

reasons of aborting the process ?

Answer 18

• child has exceeded allocated resources
• task assigned to child is no longer required.
• the parent exits and OS does not allow a child to continue if its parent terminates.

Question 19

Google Chrome Browser is multi process, what are they?

Answer 19

• Browser process manages user interface, disk and network I/O.
• Renderer process renders web pages.
• Plug-in process for each type of plug-in.

Question 20

when medium term scheduler added ?

Answer 20

If degree of multi programming needs to decrease.

Question 21

what are types of process in the system ?

Answer 21

• independent

- cooperating : which may be affect or being affected by others.

Question 22

what are reasons of cooperating ?

Answer 22

• information sharing
• convenience
• modularity
• computation speed up

Question 23

What are models of IPC ?

Answer 23

• shared memory
  The control is under the user processes.
  issue : providing synchronization mechanism of process actions.
• message receiving : processes communicating each other from shared variable.
  message size is fixed or variable.

Question 24

what are message passing implementations ?

Answer 24

• direct or indirect.
• synchronous or asynchronous
• automatic or explicit buffering.

Question 25

what are Communications in Client-Server Systems ?

Answer 25

• sockets.
• pipes.
• remote procedure call.
• remote method invocation.

Question 26

what is a socket ?

Answer 26

It is defined as an endpoint for communication.

terminology : A pair of processes communicating over a network employ of a pair of sockets- one for each process