Hardware Reference
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C
T
i
i
Server
τ
1
5
1
C
s
= 5
= 10
τ
4
15
2
T
s
τ
1
τ
2
2
2
aperiodic
requests
SS active
C
s
+2
5
+2
3
1
0
2
4
6
8
10
12
14
16
18
20
22
Figure 5.17
Example of a medium-priority Sporadic Server.
by
τ
1
at
t
=5, is resumed at
t
=6and is completed at
t
=7. At this time, the replen-
ishment amount to be done at
RT
2
is set equal to the capacity consumed in [4
,
7]; that
is,
RA
2
=2.
Note that during preemption intervals SS stays active. This allows performing a single
replenishment, even if SS provides a discontinuous service for aperiodic requests.
At time
t
=8, SS becomes active again and a new replenishment is set at
RT
3
=
t
+
T
s
=18.At
t
=11, SS becomes idle and the replenishment amount to be done at
RT
3
is set to
RA
3
=2.
Figure 5.18 illustrates another example of aperiodic service in which SS is the highest-
priority task. Here, the first aperiodic request arrives at time
t
=2and consumes the
whole server capacity. Hence, a replenishment amount
RA
1
=2is set at
RT
1
=10.
The second request arrives when
C
s
=0. In this case, the replenishment time
RT
2
is
set as soon as the capacity becomes greater than zero. Since this occurs at time
t
=10,
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