Lesson 3: Process Management Flashcards
unit of work in most systems
Process
program in execution; process execution must progress in sequential fashion
Process
set of associated resources
Process
Examples of Processes
Compiler
Word processor
Email program
Sending output to a printer
T or F: Although 2 processes may be associated with the same program, they are considered 2 separate execution sequences.
True
What does a process include? (PSDT)
Program counter
Stack
Data Section
Text Section
[What does a process include] specifies the next instruction to be executed
Program counter
[What does a process include] contains temporary data
Stack
[What does a process include] contains global variables
Data section
[What does a process include] program code
Text section
Representation of a process in the operating system
PCB
What does PCB stand for?
Process Control Block
[PCB] Different states as a process executes (NRRWT)
New
Ready
Running
Waiting
Terminated
[Process State] the process is being created
New
[Process State] The process is waiting to be assigned to a processor
Ready
[Process State] Instructions are being executed
Running
[Process State] The process is waiting for some event to occur
Waiting
[Process State] The process has finished execution
Terminated
[PCB] contains the memory address of the next instruction to be executed for this process
Program counter
[PCB] CPU registers include: (ASIG)
Accumulators
Stack Pointers
Index Registers
General Purpose Registers
[PCB] Memory-management information includes: (VPS)
Value of base and limit registers
Page tables
Segment tables
[PCB] I/O Status information includes
list of I/O devices allocated to this process, list of open files, etc.
[PCB] CPU scheduling information includes: (PPS)
Process priority
Pointers to scheduling queues
Scheduling Parameters
[PCB] Accounting information includes (RLAJ)
Amount of CPU and REAL TIME used
Time LIMITS
Account numbers
Job or process number, etc.
Process Scheduling Queues (JRD /jared/)
Job queue
Ready queue
Device queues
[Process Scheduling Queues] set of all processes in the system
Job queue
[Process Scheduling Queues] set of all processes residing in main memory, ready and waiting to execute
Ready queue
[Process Scheduling Queues] set of processes waiting for an I/O device
Device queues
Schedulers (LS)
Long-term scheduler (job scheduler)
Short-term scheduler (CPU scheduler)
[Schedulers]
—selects which processes should be brought into the ready queue
—invoked very infrequently
—controls the degree of multiprogramming
Long-term scheduler (job scheduler)
[Schedulers]
—selects which process should be executed next and allocates CPU.
—invoked very frequently
Short-term scheduler