Architectural performance analysis of FPGA synthesized LEON processors

Damman, Corentin; Edison, Gregory; Guet, Fabrice; Noulard, Eric; Santinelli, Luca; Hugues, Jérôme

doi:10.1145/2990299.2990306

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…Before each run, inputs of the components are shuffled or randomly generated. Then, caches are flushed as explained in [64] and current time is fetched from RTOS which basically gets the current time value from a timer in nanoseconds resolution.…”

Section: Definition Of Inputsmentioning

confidence: 99%

Hybrid probabilistic timing analysis with Extreme Value Theory and Copulas

BEKDEMIR

Bazlamaçcı

2022

Microprocessors and Microsystems

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The primary challenge of time-critical systems is to ensure that a task completes its execution before its deadline. In order to ensure that the underlying system comply with stringent timing requirements, designers ought to analyze the timing behavior of the software and its sub-components. Worst-Case Execution Time (WCET) represents the maximum length of time an individual software unit takes to execute and is the most essential value for schedulability analysis in safety-critical systems. Recent studies focus on statistical approaches which augments measurement-based timing analysis with probabilistic confidence level by applying stochastic methods.Common approaches either utilize Extreme Value Theory(EVT) for end-to-end measurements or convolution techniques for a group of program units to derive absolute upper distributional bound of the whole program. The former method lacks insurance of path coverage while the latter one suffers from ignoring possible extreme cases of program units. Furthermore, current state-of-the-art convolution method that is being implemented by a commercial WCET analysis tool overestimates the results under the assumption of worst dependence between the basic blocks. v In this thesis, we propose a hybrid probabilistic timing analysis framework based on modeling the program units with EVT to capture extreme cases and Copulas to model the dependency between the units to derive tighter distributional bounds to mitigate the effects of comonotonic assumptions. The proposed framework also offers a way to minimize the instrumentation probe effects which is essential to obtain fine-grained execution time traces on COTS platforms.

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Section: Definition Of Inputsmentioning

confidence: 99%

Hybrid probabilistic timing analysis with Extreme Value Theory and Copulas

BEKDEMIR

Bazlamaçcı

2022

Microprocessors and Microsystems

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“…Some effort has been dedicated in previous works to identify the best model that fits the worst-case execution time values. The results are controversial: some researchers [2,10,11,25] claim we should consider only the Weibull or Gumbel distribution, while others [30,44] do not exclude the Fréchet too. The Gumbel distribution is often the only one taken into account because it is an upper-bound of the Weibull, however, it is not always possible to use such upper-bound strategy without hindering the result reliability [38].…”

Section: Evt Distribution Classesmentioning

confidence: 99%

Dealing with Uncertainty in pWCET Estimations

Reghenzani

Santinelli

Fornaciari

2020

ACM Trans. Embed. Comput. Syst.

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The problem of estimating a tight and safe Worst-Case Execution Time (WCET), needed for certification in safety-critical environment, is a challenging problem for modern embedded systems. A possible solution proposed in last years is to exploit statistical tools to obtain a probability distribution of the WCET. These probabilistic real-time analyses for WCET are however subject to errors, even when all the applicability hypotheses are satisfied and verified. This is caused by the uncertainties of the probabilistic-WCET distribution estimator. This article aims at improving the measurement-based probabilistic timing analysis approach providing some techniques to analyze and deal with such uncertainties. The so-called region of acceptance model based on state-of-the-art statistical test procedures is defined over the distribution space parameters. From this model, a set of strategies is derived and discussed, to provide the methodology to deal with the trade-off safety/tightness of the WCET estimation. These techniques are then tested over real datasets, including industrial safety-critical applications, to show the increased value of using the proposed approach in probabilistic WCET analyses.

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