2 Processes

Front 1

As a process executes, it changes state. We can define the following Process States:

Back 1

Ready: Process would do something if the CPU was available.

Running: Process is being executed by the CPU.

Blocked: Process cannot continue until some event occurs.

Front 2

If we assume a single CPU,

Back 2

only one process can be running at a time.

Front 3

A process initially goes to the back on the ready list.

Then Dispatcher does what :?

Back 3

Dispatcher takes process at head of ready list and transforms its state to Running.

Front 4

Each process is allocated the CPU for a specific interval what is it called

Back 4

Quantam

Front 5

A hardware interrupting clock generates an interrupt, returns control to the OS, returns this process’s state to ????, and makes the first process on the ready list ???

Back 5

A hardware interrupting clock generates an interrupt, returns control to the OS, returns this process’s state to Ready, and makes the first process on the ready list Running

Front 6

Processes can be suspended, and later resumed. Suspension involves

Back 6

Processes can be suspended, and later resumed. Suspension involves removing the process from main memory and storing it on secondary storage.

Front 7

The usual reasons are:
Tell me three?

Back 7

the process may not be immediately available for execution
to release some main memory to a process that is ready to execute
a process may be suspected of causing a problem
if a process is active only periodically
user action, eg. for debugging purposes.
to reduce system load at peak times,

Front 8

A process in the blocked state is not doing anything, so why not wait until it becomes unblocked and transfer its state to Ready, and then to ??????? Ready?

Back 8

A process in the blocked state is not doing anything, so why not wait until it becomes unblocked and transfer its state to Ready, and then to Suspended Ready?

Front 9

The PCB is a data structure containing all the information about a process needed by the OS including:

Name 3 of them

Back 9

Current state
Process ID
Pointer to parent
Pointers to children
Program counter
Priority
Pointers to process’s memory
Pointers to allocated resources
Register save area
List of open files

Front 10

Hardware registers and instructions ensure fast availability

Back 10

PCB INFORMATION

Front 11

The OS must have the capability of performing the following operations on processes.
Name as many as you can

Back 11

Create (naming; inserting into process table; find priority; create PCB; allocate resources)
Destroy
Suspend
Resume
Change priority
Block
Wakeup
Dispatch
Enable intercommunication
Enable spawning (parent/child relationship)

Front 12

A process switch may occur any time that the OS has gained control from the

Back 12

currently running process.

Front 13

There are three events that may cause the OS to gain control

Back 13

Interrupt. With an ordinary interrupt, control is passed to an interrupt handler, which does some basic housekeeping and then branches to an OS routine that is concerned with the particular type of interrupt that has occured, eg. clock, I/O event, memory fault
Trap. This relates to an error or exception condition generated within the current process, eg. illegal file access. The OS first determines if the condition is fatal, in which case it is terminated. Otherwise the action depends on the nature of the error (eg. it may simply inform the user)
Supervisor Call. The OS may be activated by a Supervisor Call from the process, eg. an instruction is executed that requests an I/O operation. This results in a transfer to a routine that is part of the OS code.

Front 14

The steps involved in a full process switch are as follows:

Back 14

Save the context of the processor (eg program counter and other registers)
Update the PCB of the process currently running
move the PCB of this process to the appropriate queue (eg. blocked, suspended)
Select another process for execution
Update the PCB of the selected process
Update memory management data structures
Restore the context of the processor to that which existed at the time the selected process was last switched out of the running state.