Information Technology Reference
In-Depth Information
Table 1 The
first volvo case
study
Task
T
i
C
i
D
i
A
10
2
10
B
20
2
5
D
50
6
50
E
100
8
100
H
2,000
8
2,000
Table 2 The added tasks to
volvo case study
Task
T
i
C
i
D
i
C
50
1
2
F
2,000
7
100
G
2,000
8
100
Five independent computations
s
A
; s
B
; r
D
; r
E
, and
r
H
, to be executed on an
embedded processor core.
r
H
are sporadic
ones. Each task can be executed immediately after its arrival and must be
s
A
and
s
B
are periodic tasks,
r
D
,
r
E
, and
finished
by its deadline. These tasks are feasible because the processor utilization factor
U = 0.804
≤
1. and should meet all required deadlines de
ned in user requirements
and we have Feasibility
ð
Current
n
ð
t
ÞÞ
True.
We suppose now, that a recon
guration scenario
w
1
is applied at time t1 to add 3
new tasks C
;
F
;
G
;
as described in Table
2
to the initial Volvo case study system
r
H
). The new pro-
cessor utilization becomes U = 1.454 > 1. Therefore the system is unfeasible and
Feasibility
s
A
; s
B
; r
D
; r
E
, and
composed of the
five characterized tasks (
ð
ð
ÞÞ
Current
t
False.
n
w
1
In our running example,
n
¼
fs
A
; s
B
; r
D
; r
E
;
and
r
H
g
is initially considered
n
ð
0
Þ
and after the 1th recon
as
guration scenario (
ðw
1
Þ
) which corresponds to the
n
¼
n
ð
0
Þ
turns into
n
ðw
1
Þ
.We
addition of the new sporadic tasks ({
r
C
,
r
F
, and
r
G
}),
de
ne VP
1
and VP
2
two virtual processors to virtually execute old (periodic and
sporadic) and new sporadic tasks implementing the system after the 1th recon
g-
uration scenario
w
1
. e.g. VP
1
will execute
τ
A
,
τ
B
,
˃
D
,
˃
E
, and
r
H
and VP
2
will
n
ðw
1
Þ
, all old tasks from
n
ðw
0
Þ
execute
r
C
,
r
F
, and
r
G
. In other words,
in
r
H
) are executed by the newly updated VP
ðw
1
Þ
1
(
s
A
; s
B
; r
D
; r
E
, and
with the
processor utilization factor UVP
ðw
1
Þ
1
r
G
)
are executed by VP
ðw
1
2
with the processor utilization factor UVP
ðw
1
2
. The proposed
intelligent agent is trying to minimize the response time R
ðw
1
Þ
of
and the added sporadic tasks (
r
C
,
r
F
, and
n
w
1
after the
recon
guration scenario
w
1
.
Proposed Solutions
After each addition scenario
w
h
, the proposed intelligent agent proposes to modify
the virtual processors, to modify the deadlines of old and new tasks, the WCETs
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