OS chapter 3 Flashcards
What is multitasking/multiprocessing/
pseudo-parallelism?
The ability to apparently run two programs at the same time.
What term refers to two processes accessing the same shared resource at the same time?
Race conditions
What is the difference between a program and a process?
A program may not be running but a process is actually running.
The IBM 1401 and 7094 computers are examples of which generation of computing?
Second generation
__________ scheduling ensures that a job is done when promised.
Guaranteed
Most modern systems use ____________.
preemptive multitaskiing
Which of the following is NOT one of the three (3) process states?
Blocked
Ready
Running
All of these are process states
All
___________ scheduling allots a time period called a quantum for each process.
Round Robin
A _________ is a running program along with data, stack, program counter, stack pointer and other registers.
process
What does the OS keep track of processes with and what information is kept?
A table that keeps the state, program counter, stack pointer, memory allocation, file status, etc.
How do processes communicate?
Interprocess communication.
How is interprocess communication used?
There are multiple means, one being with interrupts, letting the processor know its time to switch processes.
Describe the process of running multiple processes: A, B, C, and D concurrently.
A runs first, then B runs, then C, Then D, then it wraps back around to A, cycling through until the processes finish. No two run at the same time.
What is a process tree?
It describes the relationship between parent child processes. Some processes spawn other processes, which are called child processes.
What is a ready process?
A process that could run, but is not on its turn.
What is a blocked process?
A blocked process has been running but is waiting for a device such as
a printer or a disk drive.
What is the critical section of a process?
The point where it accesses shared resources.
What is mutual exclusion?
When you lock out processes from accessing an in-use resource.
What are the different process priority criteria and what do they mean?
Fairness - each process gets equal share of the CPU time.
Efficiency - keep the CPU busy.
Response time minimal for interactive users.
Turnaround minimal for batch users.
Throughput - maximize number of jobs per hour.
What kinds of process scheduling do computers use?
run-to-completion scheduling
preemptive multitasking
cooperative multitasking
What is preemptive multitasking?
A system that has a process run for a set maximum amount of time, and then interrupts it for another process to begin.
Types of process scheduling
Round robin
Priority
Shortest Job first
Guaranteed scheduling
What is Priority scheduling?
Gives the most important job top priority.
What is Round Robin Scheduling?
allots a time period called a quantum for each process.
What is a quantum in process scheduling?
The length of time given to a process to run.
What is Guaranteed scheduling?
ensures that a job is done when
promised.
