L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, Jan. 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... arbitrary periods, task executions may get out of phase resulting in large latencies in communications [21] Harmonicity constraints are used to simplify the reading writing logic and reduce the communication latencies [20] Also harmonic periods increase the feasible processor utilization bound [25]. To this end, the period of the consumer is often made to be a multiple of the period of the producer: Figure 5 gives an example of such a task graph. We use this task graph for illustration since it is more general than the tasks of Figure 2. 8 C. Our Goal and Overview of Our ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

.... fresh inputs. It is not at all obvious that the software architecture meets its deadline requirements. In this section, we perform a formal analysis to check whether this is the case. We use results from real time scheduling theory, in particular, xed priority scheduling theory (e.g. see [8, 7, 5, 14, 1, 2, 15]) and the so called HKL model and analysis [3, 4] First, we cast the platoon application into the formal model. Then, we estimate the execution times and other latencies involved in the system, and compute the total CPU utilization. This is found to be about 74 , that is, less than 1, which is a ....

L. Sha, R. Rajkumar, and S.S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. IEEE Proceedings, January 1994.

....premise. At any given time, the highest priority runnable tasks are being executed. This assumes that tasks can be preempted if a higher priority task is ready to be executed. Priority scheduling algorithms differ in how priorities are allocated to tasks. Generalized Rate Monotonic Scheduling [1, 14] (GRM) utilizes static priorities to schedule periodic tasks. The key idea is to assign priorities based on periodic arrival rates where the highest priority is assigned to the task with the shortest period. Dynamic Priority Scheduling is also known as Earliest Deadline First [6] EDF) scheduling. ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--81, 1994.

.... run with arbitrary periods, task executions may get out of phase, which results in large latencies in communication [21] Harmonicity constraints can simplify the reading writing logic and reduce those latencies [20] Harmonic periods may also increase the feasible processor utilization bound [25]. To this end, we assume the period of the consumer is a multiple of that of the related producer. 2.2 Our Goal Given a set of sites and a set of functionally equivalent strategies, our goal is to find a feasible strategy. A strategy is feasible if and only if: within the LCM (Least Common ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....communication scheduling in distributed systems and presented an analysis. TTP implements the TDMA (time division multiple access) scheduling strategy. Both contributions assume a periodic activation of processes. Recent extensions of the mentioned work allow periodic activation with jitter, e.g. [15], and arbitrary deadlines and burst [8] for static priority scheduling. Sprunt et al. 16] analyze the influence of sporadic process activation. Unfortunately, all mentioned approaches assume a single coherent scheduling strategy for a given system, whether single or multiprocessor. Very few ....

....scheduled according to the rate monotonic priority assignment [10] while a round robin scheduler alternately assigns CPU 2 to either of its processes. The time slots for P 3 and P 4 are t P 3 ,slot = 5ms and t P 4 ,slot = 3ms, respectively. The core execution time intervals of the processes are [15,17]ms for P 1 , and [8, 11]ms, 10,11]ms, and [3, 5]ms for the processes P 2 , P 3 , and P 4 , respectively. We are looking for conservative (upper and lower) bounds on the response times for each event that is input to the system until a corresponding event is output to the environment. For ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....0.3]t 0.3t t 0.8t Pu [0.6, 1] tl tl 16 tl 16 tl P3 [1.1, 1.2] tl 1. 2tl 8tl Table h Latency Time Intervals and GRMS Param eters To give a simple example how the performance of a system modeled in the SPI model can be validated, we apply a generalized rate monotonic scheduling analysis method [3] to verify if the system is schedulable under the given timing constraints. This method can be applied and the processes can be seen as independent since their communication is nonblocking. The latency path constraint over process P1 can be accounted for as deadline D1 while for the other ....

L. Sha, R. Rajkumar, and S.S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68-82, January 1994.

....protocol) for communication scheduling in distributed systems and presented an analysis. TTP implements the TDMA (time division multiple access) scheduling strategy. Both contributions assume a periodic activation of processes. Recent extensions allow periodic activation with jitter, e.g. [19], and arbitrary deadlines and burst [11] for static priority scheduling. Sprunt et al. 20] analyze the influence of sporadic process activation. Unfortunately, all mentioned approaches assume a single coherent scheduling strategy for a given system, whether single or multi processor. Very few ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....models, e.g. periodic or burst. From the IP perspective, these can be used to specify operation conditions for which the response times are guaranteed. For single component systems, the resource level already is the system level. There also exist many techniques for homogeneous multi processors [20]. However, this does not hold for heterogeneous multi component systems. The system level analysis for heterogeneous HW SW platforms has been neglected for a long time. In a recent publication, Pop et al. 17] extended the existing scheduling analysis to specialized classes of multi component ....

....for communication scheduling in distributed systems and presented an analysis. TTP implements the TDMA (time division multiple access) scheduling strategy. Both contributions assume a periodic activation of tasks. Recent extensions of the mentioned work allow periodic activation with jitter, e.g. [20], and arbitrary deadlines [12] Sprunt et al. 21] analyze the influence of sporadic task preemption. Tindell presents an approach for task bursts [24] Gresser [7] and Thiele et al. 23] use more general activation models. They introduce a vector of sequential time intervals rather than a few ....

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L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....in aerospace avionics, transportation, multimedia, digital TV, etc, have to serve a mixture of time critical and conventional, interactive or batch computing functions. It is very expensive to build a real time OS starting from the device driver level up to enforce real time scheduling theories [12, 18]. A more cost effective alternative is extending commercial, off the shelf Operating Systems (COTS) for real time service, which could allow the coexistence of time constraint and conventional applications on the same paltform. Middleware is a (mostly) user level software layer, which fills in the ....

Sha, L., Ragunathan, R. and Sathaye, S., "Generalized Rate-Monotonic Scheduling Theory: A Framework for Developing Real-Time Systems," in Proceedings of the IEEE, Vol. 20, No. 1, pp. 68--82, Jan. 1994.

....the system we use the run time scheduler of [16, 18, 19] Previous approaches to real time analysis have focused on software [2] since the performance analysis of ASICs is considered a well studied problem already. Rate Mono tonic Analysis (RMA) 3] and Generalized Rate Monotonic Analysis (GRMA) [4] both assume that tasks are independent and that each task has its own period and deadline. RMA has been extended to account for re lease jitter and resource contention [5, 6] RMA has also been extended to allow precedence among tasks by formulating the problem as a big task with the length of ....

L. Sha, R. Rajkumar and S. Sathaye, "Generalized rate monotonic scheduling theory: a framework for developing real-time systems," Proceedings of the IEEE, 82(1):68-82, January 1994.

....while we can handle any LTL formula. Moreover, only infinite paths can be selected in these works. A Distributed Real TimeSystem: To demonstrate the usefulness of our method, we have applied it to a distributed real time system of realistic complexity, derived from the example described in [27]. Real time systems are used in many critical applications such as aircraft control or medical monitoring systems. Because of the consequences of failures in such systems, determining their correctness is a vital task. Several features of this example make it an interesting target for our ....

....control processor. However, verifying that these deadlines are met using standard techniques is made more difficult because of the distributed nature of the problem. Analytical methods such as the rate monotonic scheduling must impose restrictions on the system, for example, intermediate deadlines [27]. The complex interaction between the various components of the system also makes its analysis using continuous time models unmanageable. Our tools, on the other hand, were able to analyze the system and verify that the deadlines are met by the design. Moreover, we have been able to identify ....

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L. Sha, R. Rajkumar, and S. Sathaye. Generalized rate-monotonic scheduling theory: a framework for developing real-time systems. In Proceedings of the IEEE, Jan 1994.

....by the rates at which the system interacts with the environment through a relatively small number of sensors and actuators. Having each processor run tasks of the same or harmonically related periods has the potential to increase its feasible utilization bound (under fixed priority scheduling) [4]. Moreover, such a task assignment is likely to reduce the least common multiple (LCM) of task periods on each machine (compared to an assignment that does not group tasks by harmonic periods) Hence, it simplifies schedulability analysis and requires a smaller amount of memory space for storing a ....

.... cluster modules with similar periods if they are harmonic multiples (in which case LCM(P i ; P j ) P j ) Unlike ffi 1 , it penalizes module pairs with non harmonic periods (where LCM(P i ; P j ) P j ) Clustering modules of harmonic periods increases the feasible processor utilization bound [4]. ffl ffi 3 = P j =LCM(P i ; P j ) This expression attempts to cluster modules with periods which are harmonic multiples. Unlike ffi 1 and ffi 2 , it does not penalize modules for having significantly different periods as long as they are harmonic. ffl ffi 4 = V ij =P i . This expression ....

[Article contains additional citation context not shown here]

L. Sha, R. Rajkumar, and S. S. Sathaye, "Generalized rate monotonic scheduling theory: A framework for developing real-time systems," Proceeding of IEEE, vol. 82, no. 1, pp. 68--82, Jan 1994.

....Traditional approaches for providing these performance assurances, such as resource reservation [23] The work reported in this paper was supported in part by the National Science Foundation under grants CCR 0093144 and CCR 0098269. and a priori knowledge of worst case execution conditions [27], are no longer applicable. To achieve predictable behavior in distributed, poorly modeled, uncertain environments of today s open performance assured applications, several recent research efforts have suggested the use of control theory [16, 30, 21, 18] This theory offers a new types of ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....with a summary of contributions and discussion of future work. 2 Related Work The traditional approach to providing guarantees in performance critical systems has been to rely on static allocation and scheduling algorithms that assume full a priori knowledge of the resource requirements of tasks [5, 31, 32, 40, 41]. The concept of dynamic real time systems [34] pioneered by the Spring kernel project [35, 36] was introduced later to describe applications where runtime workload is unknown until admission control time. It resulted in innovative planning based scheduling algorithms that provide online ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

....of the application. A widely used way to make schedulability analysis is to use an o ine worst case execution time (WCET) calculation. However, when several processes (or threads) interact via shared data, this calculation often becomes extremely complicated. This problem has been addressed in [9] using a framework where the o ine analysis is extended with some application dependent knowledge and use of priority Basic Research in Computer Science, Centre of the Danish National Research Foundation. 1 inheritants protocol. The work described in this paper is directed towards automatic ....

L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1), January 1994.

....Hence, it s difficult to achieve service differentiation and allocation guarantee using a best effort scheduler. In order to meet the timeliness requirements presented by multimedia applications, much work in recent years has been focusing on applying real time techniques to multimedia systems [50, 36, 70, 44, 79, 22, 10, 39, 80, 73, 72, 56]. However, most of real time schedulers require the global knowledge of the workload and the precise CPU bandwidth requirement of each application. As described in Section 1.2, such information is often hard to obtain in a dynamic environment featuring multimedia applications. Furthermore, ....

....the timeliness requirements presented by multimedia applications, much work in recent years has been focusing on applying real time techniques to multimedia systems. Classical real time scheduling algorithms such as the Earliest Deadline First (EDF) 94 Rate Monotonic (RM) and their variations [50, 36, 70, 44] are suitable for hard real time applications. However, when applying to multimedia applications, several difficulties arise. First, most conventional real time schedulers assume global knowledge of resource requirements (e.g. period, deadline, computational requirements) of a workload to ....

L. Sha, R. Rajkumar, and S.S. Sathaye. Generalized Rate-Monotonic Scheduling Theory: A Framework for Developing Real-Time Systems. In Proceedings of the IEEE, number 1, pages 68--82, January 1994. 117

....alternative program units. Because it does not require rollback, analytic redundancy is an example of a forward recovery method. 3.3 Rate Monotonic Scheduling Theory For real time systems, we also have to be able to make performance guarantees. Generalized Rate Monotonic Scheduling (GRMS) Theory [Sha 94] guarantees that, as long as certain conditions are met (e.g. task execution time, strict adherence to priority, etc. a given task set can be guaranteed to meet its deadlines. Rate Monotonic Analysis (RMA) techniques coupled with the appropriate real time operating system scheduling support ....

Sha, L.; Rajkumar, R.; & Sathaye, S. "Generalized Rate Monotonic Scheduling Theory: A Framework for Developing Real-time Systems, " Proceedings of the IEEE, January 1994.

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L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate-monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, Jan. 1994.

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L. Sha, R. Rajkumar, S. S. Sathaye, Generalized Rate Monotonic Scheduling Theory: A Framework for Developing Real-time Systems, Proceedings of the IEEE 82 (1).

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L.Sha, R.Rajkumar, S.S.Sathaye, \Generalized Rate Monotonic Scheduling Theory: a Framework for Developing Real Time Systems," IEEE Proceedings, Vol.82, No.1, 1994.

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L.Sha, R.Rajkumar, S.S.Sathaye, \Generalized Rate Monotonic Scheduling Theory: a Framework for Developing Real Time Systems," Proceedings of the IEEE, Vol.82, No.1, Jan.1994.

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L. Sha, R. Rajkumar and S. Sathaye, "Generalized rate monotonic scheduling theory: a framework for developing real-time systems," Proceedings of the IEEE, 82(1):68-82, January 1994.

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L. Sha, R. Rajkumar, and S. Sathaye. Generalized rate monotonic scheduling theory, a framework of developing real-time systems. Proceedings of The IEEE, January 1994.

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L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized RateMonotonic Scheduling Theory: A Framework for Developing Real-Time Systems. Proceedings of the IEEE, 82(1):68-- 82, January 1994.

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L. Sha, R. Rajkumar, and S. S. Sathaye. Generalized rate monotonic scheduling theory: A framework for developing real-time systems. Proceedings of the IEEE, 82(1):68--82, January 1994.

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