TY - GEN
T1 - Limitations of Ada® for real-time scheduling
AU - Cornhill, Dennis
AU - Sha, Lui
AU - Lehoczky, John P.
AU - Rajkumar, Ragunathan
AU - Tokuda, Hide
PY - 1987/10/1
Y1 - 1987/10/1
N2 - The goal in real-time scheduling is to satisfy the timing requirements of application jobs which often have hard deadlines. There are two aspects to Ada's scheduling policies which are detrimental to achieving this goal. First, Ada's constraints on the language's implementation limit the definition of priority and the task scheduling algorithm to preclude the use of the best algorithms for scheduling jobs with hard deadlines. Second, information about task priority is not used when selecting a task from an entry queue or when choosing among branches of a selective wait statement. Instead, FIFO and arbitrary disciplines are used, respectively, which can unnecessarily lead to missed deadlines, even for very low levels of processor utilization. We suggest some areas for change to make the language more suitable for building real-time systems.
AB - The goal in real-time scheduling is to satisfy the timing requirements of application jobs which often have hard deadlines. There are two aspects to Ada's scheduling policies which are detrimental to achieving this goal. First, Ada's constraints on the language's implementation limit the definition of priority and the task scheduling algorithm to preclude the use of the best algorithms for scheduling jobs with hard deadlines. Second, information about task priority is not used when selecting a task from an entry queue or when choosing among branches of a selective wait statement. Instead, FIFO and arbitrary disciplines are used, respectively, which can unnecessarily lead to missed deadlines, even for very low levels of processor utilization. We suggest some areas for change to make the language more suitable for building real-time systems.
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U2 - 10.1145/36821.36798
DO - 10.1145/36821.36798
M3 - Conference contribution
AN - SCOPUS:38349019160
T3 - Proceedings of the 1st International Workshop on Real-Time Ada Issues, IRTAW 1987
SP - 33
EP - 39
BT - Proceedings of the 1st International Workshop on Real-Time Ada Issues, IRTAW 1987
A2 - Barnes, John
PB - Association for Computing Machinery, Inc
T2 - 1st International Workshop on Real-Time Ada Issues, IRTAW 1987
Y2 - 13 May 1987 through 15 May 1987
ER -