| 1. |
- Barkah, Dani, et al.
(författare)
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Evaluation of Automatic Flow Analysis for WCET Calculation on Industrial Real-Time System Code
- 2008
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Ingår i: Proceedings - Euromicro Conference on Real-Time Systems, 2008. - 9780769532981 ; , s. 331-340
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Konferensbidrag (refereegranskat)abstract
- A static Worst-Case Execution Time (WCET) analysis derives upper bounds for the execution times of programs. Such analysts requires information about the possible program flows. The current practice is to provide this information manually, which can be laborious and error-prone. An alternative is to derive this information through an automated flow analysis. In this article, we present a case study where an automatic flowanalysis method was tested on industrial real-time system code. The same code was the subject of an earlier WCET case study, where it was analysed using manual annotations for the flow information. The purpose of the current study was to see to which extent the same flow information could be found automatically. The results show that for the most part this is indeed possible, and we could derive comparable WCET estimates using the automatically generated flow information. In addition, valuable insights were gained on what is needed to make flow analysis methods work on real production code.
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| 2. |
- Ermedahl, Andreas, et al.
(författare)
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Loop Bound Analysis based on a Combination of Program Slicing, Abstract Interpretation, and Invariant Analysis
- 2007
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Ingår i: OpenAccess Series in Informatics, Volume 6, 2007. - 9783939897057
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Konferensbidrag (refereegranskat)abstract
- Static Worst-Case Execution Time (WCET) analysis is a technique to derive upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component for static derivation of precise WCET estimates is upper bounds on the number of times different loops can be iterated. In this paper we present an approach for deriving upper loop bounds based on a combination of standard program analysis techniques. The idea is to bound the number of different states in the loop which can influence the exit conditions. Given that the loop terminates, this number provides an upper loop bound. An algorithm based on the approach has been implemented in our WCET analysis tool SWEET. We evaluate the algorithm on a number of standard WCET benchmarks, giving evidence that it is capable to derive valid bounds for many types of loops.
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| 3. |
- Gustafsson, Jan, et al.
(författare)
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ALF - A Language for WCET Flow Analysis
- 2009
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Ingår i: OpenAccess Series in Informatics Volume 10, 2009. - 9783939897149
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Konferensbidrag (refereegranskat)abstract
- Static Worst-Case Execution Time (WCET) analysis derives upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component in static WCET analysis is the flow analysis, which derives bounds on the number of times different code entities can be executed. Examples of flow information derived by a flow analysis are loop bounds and infeasible paths. Flow analysis can be performed on source code, intermediate code, or binary code: for the latter, there is a proliferation of instruction sets. Thus, flow analysis must deal with many code formats. However, the basic flow analysis techniques are more or less the same regardless of the code format. Thus, an interesting option is to define a common code format for flow analysis, which also allows for easy translation from the other formats. Flow analyses for this common format will then be portable, in principle supporting all types of code formats which can be translated to this format. Further, a common format simplifies the development of flow analyses, since only one specific code format needs to be targeted. This paper presents such a common code format, the ALF language (ARTIST2 Language for WCET Flow Analysis).
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| 4. |
- Gustafsson, Jan, et al.
(författare)
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Automatic Derivation of Loop Bounds and Infeasible Paths for WCET Analysis using Abstract Execution
- 2006
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Ingår i: Proceedings - Real-Time Systems Symposium. - 0769527612 ; , s. 57-66
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Konferensbidrag (refereegranskat)abstract
- Static Worst-Case Execution Time (WCET) analysis is a technique to derive upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component for statically deriving safe and tight WCET bounds is information on the possible program flow through the program. Such flow information can be provided manually by user annotations, or automatically by a flow analysis. To make WCET analysis as simple and safe as possible, it should preferably be automatically derived, with no or very limited user interaction. In this paper we present a method for deriving such flow information called abstract execution. This method can automatically calculate loop bounds, bounds for including nested loops, as well as many types of infeasible paths. Our evaluations show that it can calculate WCET estimates automatically, without any user annotations, for a range of benchmark programs, and that our techniques for nested loops and infeasible paths sometimes can give substantially better WCET estimates than using loop bounds analysis only.
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| 5. |
- Heymowski, Andreas (red.), et al.
(författare)
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GJIJROKASTRA : TO RESTORE A WORLD HERITAGE
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This catalouge of an exhibition about restoration art in Gjirokastra is a result of the academic year 08/09 of Resturation Arts at Royal University of Fine Arts Department of Architectural conservation.
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| 6. |
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| 7. |
- Sandberg, Andreas, 1984-, et al.
(författare)
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Efficient detection of communication in multi-cores
- 2009
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Ingår i: Proc. 2nd Swedish Workshop on Multi-Core Computing. - Uppsala, Sweden : Department of Information Technology, Uppsala University. ; , s. 119-121
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several methods have been proposed to model communication in systems with coherent caches, e.g. multi-cores, however they usually incur a large overhead on the application being analyzed. In this work we describe a low-overhead statistical communication model that is driven by a sparse sample of the memory accesses in the target application. Our model allows detection of hot-spots where coherence communication occurs between different threads in an application. Preliminary results suggest that we are able to detect most of the communication hot-spots in real applications with lower overhead than previously proposed models.
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| 8. |
- Sandberg, Christer, et al.
(författare)
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Faster WCET Flow Analysis by Program Slicing
- 2006
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Ingår i: ACM SIGPLAN Notices, Volume 41, Issue 7, July 2006. - : Association for Computing Machinery (ACM). - 159593362X ; , s. 103-112
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Konferensbidrag (refereegranskat)abstract
- Static Worst-Case Execution Time (WCET) analysis is a technique to derive upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. WCET analysis needs a program flow analysis to derive constraints on the possible execution paths of the analysed program, like iteration bounds for loops and dependences between conditionals.Current WCET analysis tools typically obtain flow information through manual annotations. Better support for automatic flow analysis would eliminate much of the need for this laborious work. However, to automatically derive high-quality flow information is hard, and solution techniques with large time and space complexity are often required.In this paper we describe how to use program slicing to reduce the computational need of flow analysis methods. The slicing identifes statements and variables which are guaranteed not to influence the program flow. When these are removed, the calculation time of our different flow analyses decreases, in some cases considerably.We also show how program slicing can be used to identify the input variables and globals that control the outcome of a particular loop or conditional. This should be valuable aid when performing WCET analysis and systematic testing of large and complex real-time programs.
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| 9. |
- Sandberg, Frida, et al.
(författare)
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Predicting spontaneous termination of atrial fibrillation using the surface ECG
- 2006
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Ingår i: Medical Engineering & Physics. - : Elsevier BV. - 1873-4030 .- 1350-4533. ; 28:8, s. 802-808
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Tidskriftsartikel (refereegranskat)abstract
- By recognizing and characterizing conditions under which atrial fibrillation (AF) is likely to terminate spontaneously or be sustained, improved treatment of sustained AF may result and unnecessary treatment of self-terminating AF avoided. Time-frequency measures that characterize AF, such as fibrillatory frequency, amplitude, and waveform shape (exponential decay), are extracted from the residual ECG following QRST cancellation. Three complexity measures are also studied, characterizing the degree of organization of atrial activity. All measures are analysed using a training set, consisting of 20 recordings of AF with known termination properties, and a test set of 30 recordings. Spontaneous termination was best predicted by a low and stable fibrillatory frequency and a low exponential decay. Using these predictors, 90% of the test set was correctly classified into terminating and sustained AF. Neither fibrillation amplitude nor the complexity measures differed significantly between the two sets. (c) 2005 IPEM. Published by Elsevier Ltd. All rights reserved.
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| 10. |
- Sandberg, Frida, et al.
(författare)
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Quantitative analysis of circadian variation in atrial fibrillation frequency
- 2009
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Ingår i: [Host publication title missing]. ; 36, s. 129-132
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Konferensbidrag (refereegranskat)abstract
- Circadian variation in atrial fibrillation (AF) frequency is explored in this paper by employing recent advances in signal processing. Once the AF frequency has been estimated and tracked by a hidden Markov model approach, the resulting trend is analyzed for the purpose of detecting and characterizing the presence of circadian variation. With cosinor analysis, the results show that the shortterm variations in AF frequency exceeds the variation that may be attributed to circadian. Using the autocorrelation method, circadian variation was detected in 13 of 18 ambulatory ECG recordings (Holter) acquired from patients with long standing persistent AF. Using the ensemble correlation method, the highest AF frequency usually occurred during the afternoon, whereas the lowest usually occurred during late night. It is concluded that circadian variation is present in most patients with long standing persistent AF but the short-term variation in AF frequency is considerable.
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| 11. |
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| 12. |
- Sjödin, Andreas, et al.
(författare)
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The populus genome integrative explorer (PopGenIE) : a new resource for exploring the populus genome
- 2009
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 182:4, s. 1013-1025
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Tidskriftsartikel (refereegranskat)abstract
- * Populus has become an important model plant system. However, utilization of the increasingly extensive collection of genetics and genomics data created by the community is currently hindered by the lack of a central resource, such as a model organism database (MOD). Such MODs offer a single entry point to the collection of resources available within a model system, typically including tools for exploring and querying those resources. * As a starting point to overcoming the lack of such an MOD for Populus, we present the Populus Genome Integrative Explorer (PopGenIE), an integrated set of tools for exploring the Populus genome and transcriptome. The resource includes genome, synteny and quantitative trait locus (QTL) browsers for exploring genetic data. * Expression tools include an electronic fluorescent pictograph (eFP) browser, expression profile plots, co-regulation within collated transcriptomics data sets, and identification of over-represented functional categories and genomic hotspot locations. A number of collated transcriptomics data sets are made available in the eFP browser to facilitate functional exploration of gene function. Additional homology and data extraction tools are provided. * PopGenIE significantly increases accessibility to Populus genomics resources and allows exploration of transcriptomics data without the need to learn or understand complex statistical analysis methods. PopGenIE is available at http://www.popgenie.org or via http://www.populusgenome.info.
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| 13. |
- Sundmark, Daniel, et al.
(författare)
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Finding DU-Paths for Testing of Multi-Tasking Real-Time Systems using WCET Analysis
- 2007
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Ingår i: OpenAccess Series in Informatics, Volume 6. - 9783939897057
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Memory corruption is one of the most common software failures. For sequential software and multitasking software with synchronized data accesses, it has been shown that program faults causing memory corruption can be detected by analyzing the relations between defines and uses of variables (DU-based testing). However, such methods are insufficient in preemptive systems, since they lack the ability to detect inter-task shared variable dependencies. In this paper, we propose the use of a system level shared variable DU analysis of preemptive multi-tasking real-time software. By deriving temporal attributes of each access to shared data using WCET analysis, and combining this information with the real-time schedule information, our method also detects inter-task shared variable dependencies
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| 14. |
- Yin, Xiao-Jun, et al.
(författare)
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Ubiquitin lysine 63 chain forming ligases regulate apical dominance in Arabidopsis
- 2007
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Ingår i: The Plant Cell. - Rockville : American society of plant biologists. - 1040-4651 .- 1532-298X. ; 19:6, s. 1898-1911
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Tidskriftsartikel (refereegranskat)abstract
- Lys-63-linked multiubiquitin chains play important roles in signal transduction in yeast and in mammals, but the functions for this type of chain in plants remain to be defined. The RING domain protein RGLG2 (for RING domain Ligase2) from Arabidopsis thaliana can be N-terminally myristoylated and localizes to the plasma membrane. It can form Lys-63-linked multiubiquitin chains in an in vitro reaction. RGLG2 has overlapping functions with its closest sequelog, RGLG1, and single mutants in either gene are inconspicuous. rglg1 rglg2 double mutant plants exhibit loss of apical dominance and altered phyllotaxy, two traits critically influenced by the plant hormone auxin. Auxin and cytokinin levels are changed, and the plants show a decreased response to exogenously added auxin. Changes in the abundance of PIN family auxin transport proteins and synthetic lethality with a mutation in the auxin transport regulator BIG suggest that the directional flow of auxin is modulated by RGLG activity. Modification of proteins by Lys-63-linked multiubiquitin chains is thus important for hormone-regulated, basic plant architecture.
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