Hardware Reference
In-Depth Information
For example, consider the same task set of Table 8.1, and suppose that
τ
2
is split in two
subjobs of 2 and 1 unit, and
τ
3
is split in two subjobs of 4 and 2 units. The schedule
produced by Deadline Monotonic with such a splitting is feasible and it is illustrated
in Figure 8.13.
1
τ
1
2+1
τ
2
4+2
τ
3
0
2
4
6
8
10
12
14
16
18
20
Figure 8.13
Schedule produced by Deadline Monotonic for the task set reported in Table
8.1, when
τ
2
is split in two subjobs of 2 and 1 unit, and
τ
3
is split in two subjobs of 4 and
2 units, respectively.
8.5.1 FEASIBILITY ANALYSIS
Feasibility analysis for task splitting can be carried out in a very similar way as the
non-preemptive case, with the following differences:
The blocking factor
B
i
to be considered for each task
τ
i
is equal to the length of
longest subjob (instead of the longest task) among those with lower priority:
q
max
j
B
i
=max
j
:
P
j
<P
i
{
−
1
}
.
(8.25)
The last non-preemptive chunk of
τ
i
is equal to
q
last
(instead of
C
i
).
i
The response time analysis for a task
τ
i
has to consider all the jobs within the longest
Level-
i
Active Period, which can be computed using the following recurrent relation:
⎧
⎨
L
(0)
i
=
B
i
+
C
i
L
(
s−
1)
i
T
h
C
h
.
=
B
i
+
h
:
P
h
≥P
i
(8.26)
L
(
s
)
i
⎩
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