J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In Sang H. Song, editor, Advances in Real-Time Systems, chapter 9, pages 199--233. Prentice Hall, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....meet al..l of its timing constraints. The pioneering work by Liu and Layland [17] derives schedulability conditions for rate monotonic scheduling and earliestdeadline first scheduling. Since then, much work on schedulability analysis has been done which includes various extensions of these results [11, 28, 25, 4, 26, 22, 18, 3]. Each of these extensions expands the applicability of schedulability analysis to real time task models with different assumptions. In particular, there has been much advance in scheduling theory to address uncertain nature of timing attributes at the design phase of a real time system. This ....

J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In Sang H. Song, editor, Advances in Real-Time Systems, chapter 9, pages 199--233. Prentice Hall, 1995.

....methods, e.g. 2,9,20] tend to focus on achieving the required system functionality, but do not spend much attention on non functional requirements. The various NFR based research communities identified this as unsatisfactory, and have proposed their own design methods for developing real time [13], highperformance [25] and reusable systems, respectively. However, all these methods focus on a single NFR and treat all other NFRs as having secondary importance, if at all. We consider these approaches unsatisfactory since the software engineer needs to balance the various NFRs for any ....

....of the evaluation depends of course on how well the model reflects real world conditions, but the results will at least pinpoint possible architectural design flaws. Mathematical modelling Various research communities, e.g. high performance computing [25] reliable systems, real time systems [13], etc. have developed mathematical models that can be used to evaluate especially operational NFRs. Different from the other approaches, the mathematical models allow for static evaluation of architectural design models. For example, performance modelling is used while engineering ....

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J.W.S. Liu, R. Ha, `Efficient Methods of Validating Timing Constraints,' in Advanced in Real-Time Systems, S.H. Son (ed.), Prentice Hall, pp. 199-223, 1995.

....that is to be provided by the system. Much less effort is spent on the non functional requirements that are to be fulfilled by the system. Object oriented methods, e.g. 2,11,21] address reusability but no assessment of the achieved result is done. Other research communities, e.g. real time [15] and fault tolerant [25] have proposed design methods that incorporate design steps for supporting their respective non functional requirement (NFR) However, these approaches generally focus on a single NFR. In our experience in systems development [4,5,16] we have identified that a system ....

....Conventional design methods, e.g. 2,9,20] tend to focus on achieving the required system functionality, rather than the non functional requirements. The various NFR based research communities identified this as unsatisfactory, and have proposed their own design methods for developing realtime [15], high performance [25] and reusable systems [12] respectively. However, all these methods focus on a single quality attribute and treat all others as having secondary importance, if at all. We consider these approaches unsatisfactory since the software engineer needs to balance the various ....

[Article contains additional citation context not shown here]

J.W.S. Liu, R. Ha, `Efficient Methods of Validating Timing Constraints,' in Advanced in Real-Time Systems, S.H. Son (ed.), Prentice Hall, pp. 199-223, 1995.

....a limited number of shared resources, the timed behavior of the system is affected by their scheduling. There has been much work on schedulability analysis that addresses the problem of determining whether or not a real time system under a particular scheduling discipline will meet its deadlines [Liu94, Bur94]. The salient aspect of schedulability analysis is its ability to capture contention and scheduling of shared resources. However, the computation models used by the scheduling work ignore the effect of process synchronization except for simple precedence relations or interactions between ....

J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In S. H. Son, editor, Advances in Real-Time Systems, chapter 9, pages 199--224. Prentice Hall 1994.

....research. 2 Related Work The pioneering work by Liu and Layland [LL73] derives schedulability conditions for rate monotonic scheduling and earliest deadline first scheduling. Since then, much work on schedulability analysis has been done which includes various extensions of these results [JP86, SLL89, SRL90, CL90, SRLR89, RSL89, LH95, Bur95]. Each of these extensions expands the applicability of schedulability analysis by allowing different task models. However, these task models are still simple; in particular, they allowed only limited types of inter task interaction and timing constraints. In contrast, our approach is more general ....

J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In Sang H. Song, editor, Advances in Real-Time Systems, chapter 9, pages 199--233. Prentice Hall, 1995.

....a system would run with a CPU load of only 1 , which is too low for most engineering purposes. Alternatively, the estimated average execution times can be used instead of the worst case. This will result in a higher CPU load, but the proof cannot guarantee, that the timing constraints are obeyed. [Liu and Ha, 1995] show efficient proofs for timing constraints in real time systems. These proofs all put constraints on the system. Leinbaugh and Yamini, 1986] present a proof for hard real time systems with signal communications between the processes. ffl As soon as the system grows, the theoretical proofs ....

....any more, if a test guarantees schedulability. S i R T iS is intended for the simulation of complex systems with potential overload. Such systems cannot be easily analyzed. Therefore, no analysis for schedulability is implemented in S i R T i S. If it is desired, other tools have to be used. [Liu and Ha, 1995] present some possibilities for analysis, that work for restricted process scenarios. Stoyenko et al. 1991] present analysis methods that have been developped for compilers for real time programming languages. These methods have been successfully tested on the language 1997 06 02 S i R T i S ....

Liu, W. S. and Ha, R. (1995). Efficient methods of validating timing-constraints. In [Son, 1995], chapter 9, pages 199--224.

....meet al..l of its timing constraints. The pioneering work by Liu and Layland [16] derives schedulability conditions for rate monotonic scheduling and earliest deadline first scheduling. Since then, much work on schedulability analysis has been done which includes various extensions of these results [11, 24, 22, 4, 23, 20, 17, 3]. Each of these extensions expands the applicability of schedulability analysis to real time task models with different assumptions. In particular, there has been much advance in scheduling theory to address uncertain nature of timing attributes at the design phase of a realtime system. This ....

J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In S. H. Song, editor, Advances in Real-Time Systems, chapter 9, pages 199--233. Prentice Hall, 1995.

....6. 2 Related Work The pioneering work by Liu and Layland [18] derives schedulability conditions for rate monotonic (RM) scheduling and earliest deadline first (EDF) scheduling. Since then, much work on schedulability analysis has been done which includes various extensions of these results [26, 24, 3, 25, 22, 19, 1]. Each of the extensions expands the applicability of schedulability analysis by allowing different task models. However, these task models are still based on simple computation models compared to what our approach allows. There is relatively little work on the specification and analysis of ....

....5 Analysis of Real Time Systems in ACSR VP The purpose of schedulability analysis is to determine whether or not a real time system with a particular scheduling discipline misses any of its deadlines. 1 1 The schedulability analysis problem is also known as the validation problem [19]. PIPSys def = T 1 k Delta Delta Delta k Tn k P) n freq; chang] fcpug T i def = Job i k Activator i ) n fstart;endg Job i def = Job i (start; 1) Exec i (0; 0) Exec i (s; t) def = s c i s 6=c 0 i ) f(cpu; pty i )g : Exec i (s 1; t 1) Exec i (s; t 1) s = ....

J. W. S. Liu and R. Ha. Efficient methods of validating timing constraints. In Sang H. Song, editor, Advances in Real-Time Systems, chapter 9, pages 199--233. Prentice Hall, 1995.

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