Biyabani S, Stankovic J, Ramamritham K. The integration of deadline and criticalness in hard real-time scheduling. Proceedings of the Real-Time Systems Symposium, 6--8 December 1998. 512 R. BUYYA ET AL.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of their deadlines or criticalness or both. The criticalness of a transaction is an indication of its level of importance. However, in actuality, these two requirements sometimes conflict with each other. That is, transactions with very short deadlines might not be very critical, and vice versa [1]. Therefore we use importance (or criticalness) of the transactions in place of the priority in the conflict resolution of optimistic concurrency control. This avoids the dilemma of priority based conflict resolution, yet integrates criticalness and deadline such that, not only do the more ....

S. R. Biyabani, J. A. Stankovic, and K. Ramamritham. The integration of deadline and criticalness in hard real-time scheduling. In Proc. of the Real-Time System Symposium, 1988.

....explicit functions of their deadlines or criticality or both. The criticality of a transaction is an indication of its level of importance. However, these two requirements sometimes conflict with each other. That is, transactions with very short deadlines might not be very critical, and vice versa [3]. In real time systems transactions are scheduled according to their priorities [27] Therefore, high priority transactions are executed before lower priority transactions. This is true only if the high priority transaction has some database operation ready for execution. If no operation from the ....

S. R. Biyabani, J. A. Stankovic, and K. Ramamritham. The integration of deadline and criticalness in hard real-time scheduling. In Proceedings of the 8th IEEE Real-Time Systems Symposium, pages 487--507, Huntsville, Alabama, USA, 1988. IEEE Computer Society Press.

....k s must be less than or equal to the difference between task k s deadline and the time we are considering. InMostCrit i t , 0, otherwise = req k t req ( k ( t ( 13 Biyabani et al. explore this kind of bilevel ranking in [BIYA88]. Most notably they offer a new sematic for the term guarantee that reflects the uncertainty of the future task set composition. They state that at request time a task is guaranteed to meet its deadline if (1) it is among the most critical tasks in the current task set, and (2) the arrivals of ....

Biyabani, S. R., Stankovic, J. A. and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proceedings of the 1988 IEEE Real-Time Systems Symposium, Huntsville, Alabama, pp. 152-160 (December 6-8, 1988).

....values to transactions, where the value of a transaction reflects the return the application expects to receive if the transaction is completed before its deadline [29] The scheduling goal for such applications is to maximize the value realized by the completed transactions. Biyabani et al. [8], Huang et al. 29] and Haritsa et al. 25] discuss some methods to establish a priority ordering among transactions that are distinguished by both values and deadlines. A key point considered in all those works is that value and deadline are two independent characteristics of RTDB transactions. ....

....deadline to be varied. The actual tradeoff made between values and deadlines is controlled by a parameter of the algorithm. In evaluating the system performance under various priority assignment policies, different performance metrics were considered by different researchers. The metric used in [8] combines the performance measurements of all value classes in terms of the fraction of guaranteed deadlines. The results presented in that work reveals that giving higher weight to deadline than to value in determining priorities results in better performance at low transaction loads. However, ....

S.R. Biyabani, J.A. Stankovic, K. Ramamritham `The Integration of Deadline and Criticalness in Hard Real-Time Scheduling', Proceedings of the 9th Real-Time Systems Symposium, 1988, pp.152-160.

....a transaction number which is unique at the originating site of the transaction, and the id of the originating site which is unique in the system. Each transaction is characterized by a criticalness and a deadline. The criticalness of a transaction is an indication of its level of importance [10]. It is assumed that each transaction is associated with one of m possible levels of criticalness (in this study, m = 3) The most critical transactions are assigned the highest level. Assignment of criticalness to a new transaction follows a uniform distribution; i.e. the criticalness of the ....

....levels (m = 3 in our simulations) w i : Weight of criticalness level i. success ratio i : Fraction of satisfied deadlines for the transactions of criticalness level i. The determination of the weights of criticalness levels is highly dependent on the particular application environment [10]. We used linearly increasing weights; i.e. w i = i; i = 1; 2; m) For each experiment, the final results were evaluated as averages over 25 independent runs. Each run continued until 1000 transactions were executed at each data site. 90 confidence intervals were obtained for the ....

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S.R.Biyabani, J.A.Stankovic, K.Ramamritham, "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling", 9th Real-Time Systems Symposium, 1988, pp.152-160.

....a task is assigned a priority that is higher than the priority of tasks whose real time performance yields lower benefit. Such an approach can be taken by carefully assigning priorities to real time tasks. A more sophisticated approach involves combining deadlines and criticalness as described in [6]. Also in the same class of approaches is the rate monotonic approach [2] wherein priority is determined by period or rate of execution. For aperiodics, timing requirements are assumed to be soft. In other words, the paradigm assumes that there is greater benefit in meeting a timing constraint ....

....with execution rates for periodics. This may not correspond to the utility perceived by the users (e.g. see the air defense example above) Furthermore, in RMA it is assumed that all on time completion times for hard real time tasks have equal utility, which may not always be the case (see [1,6]) 3.3 The use of benefit in scheduling Real Time systems It is important to distinguish between time invariant benefit and time varying benefit. In [1] Jensen points out the following: In fixed priority scheduler systems, deadline management is attempted by assigning a high fixed priority to ....

S. R. Biyabani, J. A. Stankovic and K. Ramamritham, "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," IEEE publication CH2618-7/88/0000/0152, 1998.

....the sum of the work remaining for tasks whose deadlines are nearer than task k s and whose criticality is at least as great as task k s must be less than or equal to the difference between task k s deadline and the time we are considering. Biyabani et al. explore this kind of bilevel ranking in [BIYA88]. They offer a new sematic for the term guarantee that reflects the uncertainty of the future task set composition. They state that at request time a task is guaranteed to meet its deadline if (1) it is among the most critical tasks in the current task set, and (2) the arrivals of subsequent tasks ....

Biyabani, S. R., Stankovic, J. A. and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proceedings of the 1988 IEEE Real-Time Systems Symposium, Huntsville, Alabama, pp. 152-160 (December 6-8, 1988).

....Therefore, we wish in this study to minimize the number of tasks that miss their deadlines; i.e. tardy tasks, as well as minimizing the amount of tardiness. In order to cope with overload situations, various researchers suggest integrating more than one attribute into the scheduling decision [3, 10, 14, 9, 22], while others suggest using an optimal policy under normal operating conditions, and switching to another policy in the presence of an overload [10, 14, 6, 8] Our goal in this study is not to detect and deal with an overload. Rather, it is to investigate the manner in which the importance of ....

S. R. Biyabani, J. A. Stankovic, "The Integration of Deadline and Criticalness in Hard Real-time Scheduling", Proceedings of IEEE Real-time Systems Symposium, 1988.

....the sum of the work remaining for tasks whose deadlines are nearer than task k s and whose criticality is at least as great as task k s must be less than or equal to the difference between task k s deadline and the time we are considering. Biyabani et al. explore this kind of bilevel ranking in [BIYA88]. Most notably they offer a new sematic for the term guarantee that reflects the uncertainty of the future task set composition. They state that at request time a task is guaranteed to meet its deadline if (1) it is among the most critical tasks in the current task set, and (2) the arrivals of ....

Biyabani, S. R., Stankovic, J. A. and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling", Proceedings of the 1988 IEEE Real-Time Systems Symposium, Huntsville, Alabama, pp. 152-160, (December 6-8, 1988).

....the solution with the best overall solution quality is sought [2] In this example, a problemindependent measure of the solution quality and its value are essential because they are used in scheduling time. Heuristic measures are also used in adaptive real time systems for scheduling time [1, 3]. The real time search proposed in this paper is different from Korf s real time heuristic searches [6] In Korf s method, a time constraint is associated for the expansion of a node in the search tree. During the time allowed, the searcher can either look deeper into the search tree or evaluate ....

S. R. Biyabani, J. A. Stankovic, and K. Ramamritham, "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proc. of the Ninth Real-Time System Symposium, pp. 152-160, IEEE, Dec. 1988.

....control protocols developed for RTDBSs. We believe that the method can serve as a simple and fast performance evaluation tool to be used in the design and analysis of priority based concurrency control protocols. 10 The criticalness of a transaction is an indication of its level of importance [3]. 5 7 9 11 13 15 d 0.0 2.0 4.0 6.0 8.0 10.0 12.0 fl ....

S. R. Biyabani, J. A. Stankovic, K. Ramamritham `The Integration of Deadline and Criticalness in Hard Real-Time Scheduling', 9th Real-Time Systems Symposium, pp.152-160, 1988.

....help a compiler to choose between two separate program transformations since the theorem provides an estimate of the worst case scheduling penalty associated with each transformation. In several simulation studies greedy scheduling has been found to be effective in scheduling a random task system [Biyabani88] [Ramamritham84] We believe that this conclusion may have been reached because the aspect ratio was not a controlled variable in the simulation. As the theorem above shows, a simulation should generate task systems with a = 1 to ensure that the worst case workloads are tested. When a = 1 then ....

Biyabani, Sara R., John A. Stankovic and Krithi Ramamritham. The Integration of Deadline and Criticalness in Hard Real-Time Scheduling. Proceedings of the IEEE Real Time System Symposium (1988) vol. 9, pp. 152-160.

....completion. For such systems the attention shifts to maximizing the value added to the system by the transactions commitment; minimizing tardiness or the number of missed deadlines becomes of secondary importance. Notice that a transaction s value and its deadline are two orthogonal properties [BSR88, HSTR89]. The fact that a transaction has a tight deadline does not in any way imply that it has a high value, nor does the fact that it has a loose deadline imply that it has a low value. Transactions with similar values may have different deadlines, while those with similar deadlines may have different ....

Sara Biyabani, John Stankovic, and Krithi Ramamritham. The integration of deadline and criticalness in hard real-time scheduling. In Prooceedings of the 9th Real-Time Systems Symposium, December 1988.

.... D i ( req k ( p D i ( p k ( i 1 = D k ( d k req k AND t req j req k req j d k ( w D i ( t ( p D i ( p k ( i 1 = D k ( d k t ( 13 Biyabani et al. explore this kind of bilevel ranking in [BIYA88]. Most notably they offer a new sematic for the term guarantee that reflects the uncertainty of the future task set composition. They state that at request time a task is guaranteed to meet its deadline if (1) it is among the most critical tasks in the current task set, and (2) the arrivals of ....

Biyabani, S. R., Stankovic, J. A. and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proceedings of the 1988 IEEE Real-Time Systems Symposium, Huntsville, Alabama, pp. 152-160 (December 6-8, 1988).

....In this scenario, therefore, the value of a transaction is the fare paid by the requesting customer, and the objective of the reservation database system is to maximize the revenue received by the airline. A key point to note here is that value and deadline are fundamentally different properties [Biya88, Huan89]. The fact that a transaction has a tight deadline does not necessarily mean that it has a high value, nor does a loose deadline imply a low value. Transactions with similar values may have different deadlines, while those with similar deadlines may have different values. The value reflects the ....

....settings of the overload probability threshold, the Best Effort algorithm provides a high realized value under a wide spectrum of loads, including both transient and persistent overloads, and a variety of value functions. A different approach to integrating value and deadline was described in [Biya88]. The basic mechanism here is that the scheduler first tries to schedule a new task according to its deadline without taking its value into consideration. This is successful if the new task s execution time is small enough that it can be completed before its deadline without jeopardizing the ....

Biyabani, S., Stankovic, J., and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proc. of the 9th Real-Time Systems Symposium, Dec. 1988.

....of transactions. 6.2.2 Processing Transactions with Soft Deadlines Transaction Priority Assignment Policies: Priorities and values for real time transactions are used for conflict resolution and CPU scheduling. The literature contains various transaction priority or value assignment algorithms [26, 75, 76, 86, 91, 134] and their evaluations [3, 1, 86] Some of these policies are Earliest deadline first, Highest value first, Least slack time first (where slack time is the maximum amount of time that a transaction can spend without executing, and still complete within its deadline) ....

Biyabani, S., Stankovic, J. A., and Ramamritham, K., "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," in Proceedings of the 9th Real-Time Systems Symposium, pp. 152--160, 1988.

....with high values arrive thus stressing the system: For example, if periodic maintenance is postponed due to the arrival of more important activities, it may eventually be necessary to shut down the system. Hence dealing with overleads is complex and solutions are still in their infancy [6, 8, 31]. An approach to this problem, based on discarding transactions immediately upon their arrival, given current system load and arriving transaction characteristics, is described in [22] In managing overloads, some of the tradeoffs that we discussed earlier, involving timeliness vs. quality are ....

S. Biyabani, J.A. Stankovic, and K. Ramamritham, "The Integration of Deadline and Criticalness in Hard Real--Time Scheduling," Proceedings of the Real-Time Systems Symposium, December 1988.

No context found.

Biyabani S, Stankovic J, Ramamritham K. The integration of deadline and criticalness in hard real-time scheduling. Proceedings of the Real-Time Systems Symposium, 6--8 December 1998. 512 R. BUYYA ET AL.

No context found.

S. Biyabani, J. Stankovic, and K. Ramamritham, "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proc. Ninth Real-Time Systems Symp., Dec. 1988.

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Sara Biyabani, John Stankovic, and Krithi Ramamritham. The integration of deadline and criticalness in hard real-time scheduling. In Proceedings of the 9th Real-Time Systems Symposium, December 1988.

No context found.

S. R. Biyabani, J. A. Stankovic, K. Ramamritham `The Integration of Deadline and Criticalness in Hard Real-Time Scheduling', 9th Real-Time Systems Symposium, pp.152-160, 1988.

No context found.

Biyabani, S., J. A. Stankovic, and K. Ramamritham, "The Integration of Deadline and Criticalness in Hard Real-Time Scheduling," Proceedings of the 9th IEEE Real-Time Systems Symposium, December 1988.

No context found.

S. Biyabani, J. Stankovic, and K. Ramamritham. The Integration of Deadline and Criticalness in Hard Real-Time Scheduling. In Proc. of the 9th Real-Time Systems Symposium, December 1988.

No context found.

S. R. Biyabani, J. A. Stankovic, K. Ramamritham `The Integration of Deadline and Criticalness in Hard Real-Time Scheduling', 9th Real-Time Systems Symposium, pp.152-160, 1988.

No context found.

S.R. Biyabani, J.A. Stankovic, and K. Ramamritham. The integration of deadline and criticalness in hard real-time scheduling. In Proceedings of the 9th Real-Time Systems Symposium, pp.152--160 (1988).

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