C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing schema. Journal of Real-Time Systems, 1(2):160--176, September 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to determine the typical case path through the graph [14] Our proposed technique is well suited as an alternative to actual profiling for such design methodologies. The static analysis of control flow of software using constructs such as unbounded looping requires designersupplied constraints [11]. A codesign example is the COSYMA environment in which a user annotates a specification to identify infeasible paths [15] Our proposed technique is specifically designed to assist an experienced designer with such annotations. 2.3 Flow Analysis The theoretical foundation of the program ....

C. Park, A. Shaw, Experiments with a program timing tool based on source-level timing schema, Proc 11 Real-time Systems Symp, 1990, pp 72-81.

....approaches for the determination of the worst case execution time of a real time program. Static analysis and measurement. Static analysis relies on a timing model of the hardware and attempts to determine an upper bound on the longest path of the program. Techniques include treebased approaches [10, 4], or path based approaches [8, 12, 13] E#orts on WCET analysis are on determining the e#ect of advanced processor features like cache, branch prediction and pipelines and their interactions [9, 6, 5, 7] However, these approaches are very complex as the processors themselves become more di#cult ....

C.Y. Park and A.P. Shaw. Experiments with a program timing tool based on source--level timing schema. IEEE Transactions on Computers, 24(5):48--57, May 1991.

....effects of the different proposed mechanisms. 2 Related Work Beside path based and implicit path enumeration based approaches, the use of timing schemas are a main theme in the area of WCET estimation research. As our method can be used as an extension of the timing schema based approach (cf. [12]) we provide a short introduction into this method. A simple timing schema is based on a syntax tree representation of the code. For each node of the tree, it computes W(X) an integer that represents the worst case execution time of X as a function of the execution time of its parts. The leaves ....

C. Park and A. Shaw. Experiments with a program timing tool based on source level timing schema. IEEE Transactions on Computers, 24(5):487, May 1991.

....in order to derive the actual WCET bounds. Three classes of calculation methods are mainly used. The tree based approach is limited to well structured codes, and assumes that the execution time bounds for programs can be directly derived from time bounds on their parts through simple rules [20]. Treebased calculation methods are straightforward, but cannot utilize complex flow constraints well. Path based techniques explicitly explore the execution paths of a program fragment [16, 24] They can handle complex flow constraints somewhat better. The Implicit Path Enumeration Technique ....

....non structural program flow constraints (such as infeasible paths, constraints on loop bounds) must be entered by manual annotations. A program representation for parametric WCET analysis has been suggested by Colin and Bernat [7] This approach extends the classical program timing schema model [20]. It requires a well structured high level program, and constraints on program flow must be provided by hand. In [4] a similar, path based approach is outlined. Vivancos et al. 26] propose an iterative method for computing WCET for loops parameterized in the number of loop iterations, where a ....

C. Park and A. Shaw. Experiments with a program timing tool based on a source-level timing schema. IEEE Computer, 24(5):48--57, 1991.

....the flow graph which lead to an infinite number of potential paths resulting in infinite execution cost intervals. Previous work divides the software analysis problem in local analysis of basic blocks and global program analysis. The approaches by Mok [18] Puschner and Koza [22] and Park and Shaw [21] require iteration bounds for all loops in the program which the designer must provide by loop annotation. While making formal analysis feasible, loop bounding alone is not sufficient for accurate path analysis. Nested loops are often interdependent and conditions depend on each other. These ....

....bounding alone is not sufficient for accurate path analysis. Nested loops are often interdependent and conditions depend on each other. These dependencies can be rather complex as shown in the example in figure 2. A language for feasible path annotation with regular expressions is introduced in [21]. Still, the number of required path annotations, which must be provided by the designer, can be extremely large in practice, as demonstrated with even small examples in [16] bb1 s=k; bb2 while (k 10) bb3 if (OK) bb4 j ; bb5 j=0; OK=true; bb6 k ; r =j; bb7 x1 x2 x3 x4 x5 x6 x7 ....

C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing scheme. In Proceedings 11th IEEE RealTime System Symposium, pages 72--81, 1990.

....There are two ways to determine what sequence of instructions will be executed. On the one hand, it is possible to consider all paths implicitly by using integer linear programming [10, 20, 15] On the other hand, the enumeration of program paths can be explicit as in tree based methods [17, 12, 3]. Some information is either required or useful to tighten path description: how many times loops iterate, dependencies between if statements, etc. This information can be user provided (through annotations embedded in the source code [16] provided separately [10] or automatically obtained ....

C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source- level timing schema. In IEEE Computer, pages 48-57, May 1991.

....important for reactive systems, interactive environments, compiler optimizations, performance evaluation, and many other computer applications. It has been extensively studied in many fields of computer science: algorithms [22, 13, 14, 41] programming languages [39, 23, 32, 36, 35] and systems [37, 30, 34, 33]. Being able to predict accurate time bounds automatically and efficiently is particularly important for many applications, such as reactive systems. It is also particularly desirable to be able to do so for high level languages [37, 30] Since Shaw proposed timing schema for analyzing system ....

....languages [39, 23, 32, 36, 35] and systems [37, 30, 34, 33] Being able to predict accurate time bounds automatically and efficiently is particularly important for many applications, such as reactive systems. It is also particularly desirable to be able to do so for high level languages [37, 30]. Since Shaw proposed timing schema for analyzing system running time based on high level languages [37] a number of people have extended it for analysis in the presence of compiler optimizations [30, 10] pipelining [17, 24] cache memory [3, 24, 12] etc. However, there is still a serious ....

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C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing schema. IEEE Comput., 24(5):48--57, 1991.

.... tree based calculation, pathbased calculation, and the Implicit Path Enumeration Technique (IPET) The tree based approach is limited to well structured codes, and assumes that the execution time bounds for programs can be directly derived from time bounds on their parts through simple rules [3, 28]. Path based techniques explicitly explore the execution paths of a program fragment [16, 33, 34] IPET, finally, models possible program flows with arithmetic constraints [11, 14, 17, 19, 27, 30] IPET is formulated for (possibly unstructured) program flow graphs, with basic blocks connected by ....

C. Park and A. Shaw. Experiments with a program timing tool based on a source-level timing schema. IEEE Computer, 24(5):48--57, 1991.

....timated. There are two ways to determine what sequence of instructions will be executed. On the one hand, it is possible to consider all paths implicitly by using integer linear programming [10, 19, 14] On the other hand, the enumeration of program paths can be explicit as in tree based methods [16, 12, 2]. Some information is either required or useful to tighten path description: how many times loops iterate, dependencies between if statements, etc. This information can be user provided (through annotations embedded in the source code [15] provided separately [10] or automatically obtained ....

C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing schema. In IEEE Computer, pages 48 57, May 1991.

....system. The AXE system and the language PLEX are introduced in [HM01] Traditional WCET Methods The basic methods how to calculate a safe and tight WCET using static analysis for imperative programming languages (like C) and simple hardware (like MC68000) was presented around 1990 [PK89, PS91]. The Timing Schema approach used in these methods assumes a structured program. It basically assigns a constant execution time for each atomic statement in the language. The WCET for a program is found by recursively combining these execution times in the language constructs. In the presence ....

C.Y. Park and A.C. Shaw. Experiments with a program timing tool based on a source-level timing schema. IEEE Computer, 24(5):48-57, 1991.

....have to be safe, i.e. they may never underestimate the real execution time, and they should be tight, i.e. the overestimation should be as small as possible. For processors with xed execution times for each instruction there are established methods to compute sharp WCET bounds [PK89,PS91] However, in modern microprocessor architectures caches and pipelines are key features for improving performance. The consequence is that the execution behaviour of the instructions cannot be analysed separately since it depends on the execution history. Therefore, the classical approaches to ....

....(other) references and less de ned execution paths lead to prohibitively high analysis times. In [LBJ 95] Lim et al. describe a general framework for the computation of WCETs of programs in the presence of pipelines and cache memories based on the timing schema approach of Park and Shaw [PS91] From the program structure a timing equation system can be derived which must be explicitly solved. An approximation to the solution for the set of timing equations has been proposed. The usage of an input and output state provides a way to modularise the timing analysis and makes especially ....

C. Y. Park and A. C. Shaw. Experiments with a Program Timing Tool Based on Source-Level Timing Schema. IEEE Computer, 24(5):48-57, May 1991.

....another task to complete. There are several factors that complicates the WCET estimation, including unstructured code (and unstructured programmers ; optimising compilers and complicated hardware with caches and pipelines. One way to get a WCET estimation is to use the Timing Schema method [PS90], which is made on the source code. It assumes that each high level operation, like memory read and write or arithmetic operation, has a corresponding best and worst case execution time, t bcet ; t wcet ] The result of the analysis will be a time interval, T bcet ; T wcet ] including ....

C.Y. Park and A.C. Shaw. Experiments with a program timing tool based on a source-level timing schema. Proceeding of 11th IEEE Real-Time Systems Symposium, pages 72-81, Dec 1990.

....Bloomington, IN 47405 7104. Corresponding author: Yanhong A. Liu. Email: liu cs.sunysb.edu. Tel: 631 632 8463. Fax: 631 632 8334. URL: http: www.cs.sunysb.edu liu . 1 studied in many elds of computer science: algorithms [25, 16, 17, 53] programming languages [50, 26, 41, 44] and systems [46, 37, 43, 42]. It is particularly important for many applications, such as real time systems and embedded systems, to be able to predict accurate time bounds and space bounds automatically and eciently, and it is particularly desirable to be able to do so for high level languages [46, 37, 38] For analyzing ....

.... and systems [46, 37, 43, 42] It is particularly important for many applications, such as real time systems and embedded systems, to be able to predict accurate time bounds and space bounds automatically and eciently, and it is particularly desirable to be able to do so for high level languages [46, 37, 38]. For analyzing system running time, since Shaw proposed timing schema for high level languages [46] a number of people have extended it for analysis in the presence of compiler optimizations [37, 12] pipelining [20, 28] cache memory [4, 28, 14] etc. However, there remains an obvious and ....

[Article contains additional citation context not shown here]

C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing schema. IEEE Comput., 24(5):48-57, 1991.

....flow graph which cannot be executed under any input condition. False path identification is mandatory for programs with loops since loops correspond to cycles in the flow graph which lead to an infinite number of potential paths. The approaches by Mok [6] Puschner and Koza [9] Park and Shaw [8] require iteration bounds for all loops in the program which the user must provide by loop annotation. The approach by Gong and Gajski [3] can partially consider false paths because the user can specify the branching probabilities. While making formal analysis feasible, loop bounding alone is not ....

....the branching probabilities. While making formal analysis feasible, loop bounding alone is not sufficient for accurate path analysis. Nested loops are often interdependent and conditions depend on each other. These dependencies can be rather complex. Therefore, as a second step in [4] and in [8], the user is asked to annotate false paths. The number of false paths can be very large. Instead of enumerating false paths or, conversely, feasible paths, a language for user annotation with regular expressions is introduced in [8] Still, the number of required path annotations can be extremely ....

[Article contains additional citation context not shown here]

C.Y. Park and A.C. Shaw. Experiments with a program timing tool based on source level timing shema. In Proceedings of the Real-Time Systems Symposium (RTSS '90), 1990.

....when transferring between machines. However, the profiler available to us did not allow the global timing to be decomposed. Estimates of the time needed for small sections of code also can be made from source code but only in restricted circumstances due to the effects of compiler optimization [ 60 ] Due to advances in compiler technology and as the i860 is a superscalar processor, we do not use this method. Instead, we timed code on a single processor within the parallel machine in order to cut out system load. Timings are assembled into a task duration histogram. The chi square and ....

C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on sourcelevel timing schema. IEEE Computer, 24(5):48--57, May 1991.

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C. Y. Park and A. C. Shaw. Experiments with a program timing tool based on source-level timing schema. Journal of Real-Time Systems, 1(2):160--176, September 1989.

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C Y Park and A C Shaw. Experiments with a program timing tool based on source-level timing schema. IEEE Computer, 24(5):48--57, May 1991.

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C Y Park and A C Shaw. Experiments with a program timing tool based on source-level timing schema. IEEE Computer, 24(5):48--57, May 1991.

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C. Y. Park and A. C. Shaw, "Experiments with a Program Timing Tool Based on a Source-Level Timing Schema," Computer 24(5) pp. 48-57 (May 1991).

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C Y Park and A C Shaw. Experiments with a program timing tool based on source-level timing schema. Computer, pages 48--57, May 1991.

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C. Y. Park and A. C. Shaw. Experiments with a Program Timing Tool based on a Source-Level Timing Schema. Computer, 24(5):48--57, May 1991.

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C Y Park and A C Shaw. Experiments with a program timing tool based on source-level timing schema. Computer, pages 48--57, May 1991.

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C Y Park and A C Shaw. Experiments with a program timing tool based on source-level timing schema. IEEE Computer, 24(5):48--57, May 1991.

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C. Y. Park and A. C. Shaw. Experiments with a Program Timing Tool based on a Source-Level Timing Schema. Computer, 24(5):48--57, May 1991.

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C. Y. Park and A. C. Shaw, `Experiments with a program timing tool based on source-level timing schema', Proceedings Real-Time Systems Symposium, 5--7 December 1990, pp. 72--81. IEEE Computer Society Press.

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