Hardware Reference
In-Depth Information
normal execution
critical section
τ
1
served
task
τ
2
server
budget
0
2
4
6
8
10
12
14
16
18
20
22
Figure 9.21
Example of extra blocking introduced when the budget is exhausted inside a
critical section.
normal execution
critical section
τ
1
served
task
server
budget
0
2
4
6
8
10
12
14
16
18
20
22
Figure 9.22
Example of budget check to allow resource sharing within reservations.
This mechanism is used in the SIRAP protocol, proposed by Behnam et al. [BSNN07,
NSBS09] to share resources among reservations. An example of such a strategy is
illustrated in Figure 9.22. In the example, since at time
t
=2the budget is
Q
k
=2
and the critical section is 4 units long, the resource is not granted and
τ
2
is suspended
until time
t
=10, when the budget is recharged. In this case,
τ
1
is able to execute im-
mediately, while
τ
2
experiences a longer delay with respect to the absence of protocol.
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