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   A           15                4

   B            9                7

   C            3                3

   D            6                1

   E           12                6


a. round robin with a time quantum of 1 minute

1 2 3 4 5   Elapsed Time


A B C D E   5

A B C D E   10

A B C D E   15

A B     D E   19

A B     D E   23

A B     D E   27

A B        E   30

A B        E   33

A B        E   36

A           E   38

A           E   40

A           E   42

A               43

A               44

A               45



Process Turnaround Time


A        45

B        35

C        13

D        26

E        42


Average Turnaround Time = 32.2 minutes


b. priority scheduling

Process Priority Turnaround Time


B        7         9

E        6        21

A        4        36

C        3        39

D        1        45


Average Turnaround Time = 30 minutes


c. FCFS (run in order 15, 9, 3, 6, and 12)

Process Turnaround Time


A        15

B        24

C        27

D        33

E        45


Average Turnaround Time = 28.8 minutes


d. shortest job first

Process Running Time Turnaround Time


C            3          3

D            6          9

B            9          18

E           12          30

A           15          45


Average Turnaround Time = 21 minutes


Consider a set of three periodic tasks with the execution profiles as follows:

Process Arrival Time Execution Time Ending Deadline
A(1) 0 10 20
A(2) 20 10 40
. . . .
. . . .
. . . .
B(1) 0 10 50
B(2) 50 10 100
. . . .
. . . .
. . . .
C(1) 0 15 50
C(2) 50 15 100
. . . .
. . . .
. . . .

Develop scheduling diagrams for this set of tasks.

Suppose that a microcontroller used in an automobile has four priority levels for interrupts. the units interrupting the controller include anImpact sensor subsystem, which needs attention with 0.1 ms, along with four other subsystems as follows:

Subsystem Interrupt Rate Max service time (ms)
Fuel/ignition 500/sec 1
Engine temperature 1/sec 100
Dashboard display 800/sec 0.2
Air conditioner 1/sec 100

Discuss how priorities could be assigned to guarantee the response time of 0.1 ms for the impact sensor and to handle each of theother critical units before the next interrupt is produced.

The impact sensor must be given the highest priority because its required response time is less than the service time for each of theother interrupts types; no other subsystem can share this highest priority.

The air conditioner can be given the lowest priority level because its function is not safety-critical.

We have two priority levels left for three subsystems.

Because the engine temperature monitor has a maximum service time of 100 ms it must have a lower priority than the display andfuel/ignition subsystems, which need several hundreds of service periods per second.

Finally, the display and fuel/ignition subsystems can share the same priority level since each can be served after the other withoutexceeding the time available before the next interrupt.

For example, if the fuel/ignition subsystem service starts right before the display interrupt, a total of 1.2 ms will elapse beforethe service routines of both interrupts are completed, whereas there is 1/800 sec - 1.25 ms available before the next dashboard display interruptarrives.

Note that we have ignored the service time for impact sensor subsystem interrupts that have the highest priority because they occurvery infrequently, and when they do, all else becomes unimportant.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Operating systems. OpenStax CNX. Aug 13, 2009 Download for free at http://cnx.org/content/col10785/1.2
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