Post on 31-Dec-2015
description
1
What is the meaning of preemption in utility based
real-time scheduling?
Raphael GuerraGerhard Fohler
TU KaiserslauternGermany
2
Utility based models
task 2
utility model
execution window
task 1
deadlineearliest start time
uti
lity
utility accrual
+
_
Calculate utility accrualReference point?
Which?
3
Preemptions in utility model
task 2
execution window
task 1
uti
lity
utility accrual
+
_
4
Preemptions in utility model
task 2
execution window
task 1
uti
lity
Calculate utility accrualReference point?
Which?What happens on preemption?
utility accrual
+
_
5
Preemptions in utility model
task 2
execution window
task 1
uti
lity
Calculate utility accrualReference point?
Which?What happens on preemption?How many?
same utility accrual?
utility accrual
+
_
6
Preemptions in utility model
task 2
execution window
task 1
Calculate utility accrualReference point?
Which?What happens on preemption?How many?
Integral over execution?
uti
lity
utility accrual
+
_
7
Motivating applications
Calculate utility accrualReference point
Multimedia display time dictates video quality
ControlInput/output dictate control performance
Integral over execution???
12
Discussion
Utility accrual Applications
Reference point
multimedia and control
Integral model does not ignore
preemption
13
Discussion
Utility accrual Applications
Reference point
can we ignore preemptions?
multimedia and control
Integral model does not ignore
preemption
are there any?