Elasticity and Petri nets

Digital electronic systems typically use synchronous clocks and primarily assume fixed duration of their operations to simplify the design process. Time elastic systems can be constructed either by replacing the clock with communication handshakes (asynchronous version) or by augmenting the clock with a synchronous version of a handshake (synchronous version). Time elastic systems can tolerate static and dynamic changes in delays (asynchronous case) or latencies (synchronous case) of operations that can be used for modularity, ease of reuse and better power-delay trade-off. This paper describes methods for the modeling, performance analysis and optimization of elastic systems using Marked Graphs and their extensions capable of describing behavior with early evaluation. The paper uses synchronous elastic systems (aka latency-tolerant systems) for illustrating the use of Petri nets, however, most of the methods can be applied without changes (except changing the delay model associated with events of the system) to asynchronous elastic systems.Peer ReviewedPostprint (author's final draft

Efficient detection of determinacy races in Cilk programs

Theory of Computing Systems323301-32

Comparison of Three Popular Parallel Programming Models on the Intel Xeon Phi

Systems with large numbers of cores have become commonplace. Accordingly, applications are shifting towards increased parallelism. In a general-purpose system, applications residing in the system compete for shared resources. Thread and task scheduling in such a multithreaded multiprogramming environment is a significant challenge. In this study, we have chosen the Intel Xeon Phi system as a modern platform to explore how popular parallel programming models, namely OpenMP, Intel Cilk Plus and Intel TBB (Threading Building Blocks) scale on manycore architectures. We have used three benchmarks with different features which exercise different aspects of the system performance. Moreover, a multiprogramming scenario is used to compare the behaviours of these models when all three applications reside in the system. Our initial results show that it is to some extent possible to infer multiprogramming performance from single-program cases

Proline is required for male gametophyte development in Arabidopsis

<p>Abstract</p> <p>Background</p> <p>In crosses between the proline-deficient mutant homozygous for <it>p5cs1</it> and heterozygous for <it>p5cs2 (p5cs1 p5cs2/P5CS2)</it>, used as male, and different Arabidopsis mutants, used as females, the <it>p5cs2</it> mutant allele was rarely transmitted to the outcrossed progeny, suggesting that the fertility of the male gametophyte carrying mutations in both <it>P5CS1</it> and <it>P5CS2</it> is severely compromised.</p> <p>Results</p> <p>To confirm the fertility defects of pollen from <it>p5cs1 p5cs2/P5CS2</it> mutants, transmission of mutant alleles through pollen was tested in two ways. First, the number of progeny inheriting a dominant sulfadiazine resistance marker linked to <it>p5cs2</it> was determined. Second, the number of <it>p5cs2/p5cs2</it> embryos was determined. A ratio of resistant to susceptible plantlets close to 50%, and the absence of aborted embryos were consistent with the hypothesis that the male gametophyte carrying both <it>p5cs1</it> and <it>p5cs2</it> alleles is rarely transmitted to the offspring. In addition, in reciprocal crosses with wild type, about 50% of the <it>p5cs2</it> mutant alleles were transmitted to the sporophytic generation when <it>p5cs1 p5cs2/P5CS2</it> was used as a female, while less than 1% of the <it>p5cs2</it> alleles could be transmitted to the outcrossed progeny when <it>p5cs1 p5cs2/P5CS2</it> was used as a male. Morphological and functional analysis of mutant pollen revealed a population of small, degenerated, and unviable pollen grains, indicating that the mutant homozygous for <it>p5cs1</it> and heterozygous for <it>p5cs2</it> is impaired in pollen development, and suggesting a role for proline in male gametophyte development. Consistent with these findings, we found that pollen from <it>p5cs1</it> homozygous mutants, display defects similar to, but less pronounced than pollen from <it>p5cs1 p5cs2/P5CS2</it> mutants. Finally, we show that pollen from <it>p5cs1 p5cs2/P5CS2</it> plants contains less proline than wild type and that exogenous proline supplied from the beginning of another development can partially complement both morphological and functional pollen defects.</p> <p>Conclusions</p> <p>Our data show that the development of the male gametophyte carrying mutations in both <it>P5CS1</it> and <it>P5CS2</it> is severely compromised, and indicate that proline is required for pollen development and transmission.</p