Hardware Reference
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priority
Num. of
blocking
pessimism
blocking
instant
transpa-
rency
deadlock
preven-
tion
implem-
entation
NPP
any
1
high
on
arrival
YES
YES
easy
HLP
fixed
1
medium
on
arrival
NO
YES
easy
PIP
fixed
α i
low
on
access
YES
NO
hard
PCP
fixed
1
medium
on
access
NO
YES
medium
SRP
any
1
medium
on
arrival
NO
YES
easy
Table 7.5
Evaluation summary of resource access protocols.
Exercises
7.1
Verify whether the following task set is schedulable by the Rate-Monotonic al-
gorithm. Apply the processor utilization approach first, and then the Response
Time Analysis:
C i
T i
B i
τ 1
4
10
5
τ 2
3
15
3
τ 3
4
20
0
7.2
Consider three periodic tasks τ 1 , τ 2 , and τ 3 (having decreasing priority) that
share three resources, A , B , and C , accessed using the Priority Inheritance
Protocol. Compute the maximum blocking time B i for each task, knowing that
the longest duration δ i,R for a task τ i on resource R is given in the following
table (there are no nested critical sections):
A
B
C
τ 1
3
0
3
τ 2
3
4
0
τ 3
4
3
6
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