Changeset 3136 for Deliverables/D6.46.5/workshops.ltx
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 Apr 12, 2013, 6:47:11 PM (7 years ago)
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Deliverables/D6.46.5/workshops.ltx
r3135 r3136 30 30 \texttt{http://cerco.cs.unibo.it/innovative\_techniques\_on\_timing\_analysis\_technical\_day} 31 31 32 It ran in parallel with a twoday workshop on Quantitative Aspects of Programming Languages (QAPL 11), sharing three sessions with that meeting. The CerCoworkshop also included presentations from Tullio Vartanegra, representing the PROARTIS Consortium (FP7ICT2009.3.4), and an invited talk from Prof. Bj{\"o}rn Lisper (M{\"a}lardalen University, SE) on Parametric WCET analysis.32 It ran in parallel with a twoday workshop on Quantitative Aspects of Programming Languages (QAPL 11), sharing three sessions with that meeting. The \cerco{} workshop also included presentations from Tullio Vartanegra, representing the PROARTIS Consortium (FP7ICT2009.3.4), and an invited talk from Prof. Bj{\"o}rn Lisper (M{\"a}lardalen University, SE) on Parametric WCET analysis. 33 33 34 34 \paragraph{Scientific Outcomes} 35 35 36 The HiPEAC workshop was one of 24 such meetings in a highly parallel programme organised over the 3 days of the main conference, while the ETAPS workshop was one of 20 workshops organised over 4 days, the two weekends which bookended the main conference, and was thus the better attended, and scientifically more fruitful, meeting.36 The HiPEAC workshop was one of 24 such meetings in a highly parallel programme organised over the 3 days of the main conference, while the ETAPS workshop was one of 20 workshops organised over 4 days, the two weekends which bookended the main conference, and was thus the better attended, and scientifically more successful, meeting. 37 37 38 Nonetheless, a fruitful discussion emerged at HiPEAC concerning 39 sourcelevel cost reasoning. Kevin Hammond's group use amortized 40 analysis techniques to connect local costs about embedded programs in 41 the Hume language to global costs, technology which it may be possible 42 to transfer to the CerCo setting. A key difference in our approaches 43 is that their Hume implementation used the high predictability of 44 their virtual machine implementation to obtain the local cost 45 information, whereas CerCo produces such information for a complex 46 nativecode compiler. 38 Nonetheless, a fruitful discussion emerged at HiPEAC concerning sourcelevel cost reasoning. Kevin Hammond's group use amortized analysis techniques to connect local costs about embedded programs in the Hume language to global costs, technology which it may be possible to transfer to the \cerco{} setting. A key difference in our approaches is that their Hume implementation uses the high predictability of their virtual machine implementation to obtain local cost information, whereas \cerco{} produces such information for a complex nativecode compiler. 47 39 48 At the ETAPS workshop Bj{\"o}rn Lisper drew attention to the many points of common interest and related techniques between the work on CerCo and his own on Parametric WCET analysis. In addition to his own technical talk, he took the opportunity to advertise, and solicit interest in, the recently formed COST Action IC1202 Timing Analysis and CostLevel Estimation (TACLe), of which he is Chair. This offers very promising potential for future collaborations and the wider communication of results from CerCo. 40 At the ETAPS workshop Bj{\"o}rn Lisper drew attention to the many points of common interest and related techniques between the work on \cerco{} and his own on Parametric WCET analysis. The main difference between what we do and what is done in the WCET community is that we use (automated) theorem proving to deal with the controlflow (i.e. to put an upper bound to the executions). The standard technique in WCET consists in using polyhedral analysis to bound the number of loop 41 iterations. That analysis produces constraints which are solved with the aid of offtheshelf linear programming tools. So the effectiveness of theorem proving in computing precise costs in \cerco{} interested him. 42 43 44 In addition to his own technical talk, he took the opportunity to advertise, and solicit interest in, the recently formed COST Action IC1202 Timing Analysis and CostLevel Estimation (TACLe), of which he is Chair. This offers very promising potential for future collaborations and the wider communication of results from \cerco{}. 49 45 50 46 A common theme emerged from the shared sessions with QAPL, and in particular the invited talk there from prof. Alessandra di Pierro on \emph{probabilistic} timing analysis: the parametrisation of a given timing analysis with respect to different cost \emph{algebras}. In the case of probabilistic analyses, costs are taken with respect to given probability distributions, with \emph{expected} costs being computed. prof. Vartanegra's talk emphasised a radical approach to such analyses, by making assumptions about the processor/cache architecture to yield an essentially deterministic analysis. 51 47 52 In the deterministic case studied in CerCo, we have taken a given, fixed, cost algebra of natural numbers (obtained from Siemens datasheet clock timings) under addition, but already Tranquili's work on \emph{dependent labelling} suggests a move to computing costs in algebras of \emph{functions} (in the case of his analysis of loop unrolling, of cost expressions parametrised with respect to valuations of the loop index variables). The implications of such a move are yet to be explored.48 In the deterministic case studied in \cerco{}, we have taken a given, fixed, cost algebra of natural numbers (obtained from Siemens datasheet clock timings) under addition, but already Tranquili's work on \emph{dependent labelling} suggests a move to computing costs in algebras of \emph{functions} (in the case of his analysis of loop unrolling, of cost expressions parametrised with respect to valuations of the loop index variables). The implications of such a move are yet to be explored. 53 49 54 50
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