scholarly journals The leaky semicolon: compositional semantic dependencies for relaxed-memory concurrency

2022 ◽  
Vol 6 (POPL) ◽  
pp. 1-30
Author(s):  
Alan Jeffrey ◽  
James Riely ◽  
Mark Batty ◽  
Simon Cooksey ◽  
Ilya Kaysin ◽  
...  
Keyword(s):  
Improve Performance ◽  
Compositional Semantic ◽  
Sequential Composition ◽  
Predicate Transformers ◽  
Relaxed Memory Model ◽  
Semantic Dependencies ◽  
Event Based ◽  
Predicate Transformer ◽  
Prior Models ◽  
Relaxed Memory

Program logics and semantics tell a pleasant story about sequential composition: when executing (S1;S2), we first execute S1 then S2. To improve performance, however, processors execute instructions out of order, and compilers reorder programs even more dramatically. By design, single-threaded systems cannot observe these reorderings; however, multiple-threaded systems can, making the story considerably less pleasant. A formal attempt to understand the resulting mess is known as a “relaxed memory model.” Prior models either fail to address sequential composition directly, or overly restrict processors and compilers, or permit nonsense thin-air behaviors which are unobservable in practice. To support sequential composition while targeting modern hardware, we enrich the standard event-based approach with preconditions and families of predicate transformers. When calculating the meaning of (S1; S2), the predicate transformer applied to the precondition of an event e from S2 is chosen based on the set of events in S1 upon which e depends. We apply this approach to two existing memory models.

scholarly journals Discrete event performance prediction of speculatively parallel temperature-accelerated dynamics

SIMULATION ◽  
2016 ◽  
Vol 92 (12) ◽  
pp. 1065-1086 ◽  
Author(s):  
Richard J Zamora ◽  
Arthur F Voter ◽  
Danny Perez ◽  
Nandakishore Santhi ◽  
Susan M Mniszewski ◽  
...  
Keyword(s):  
Discrete Event ◽  
Dynamical Evolution ◽  
Simple Algorithm ◽  
Computational Method ◽  
Complex Nature ◽  
Improve Performance ◽  
State Evolution ◽  
Interacting Atoms ◽  
Event Based ◽  
Thermal Vibrations

Due to its unrivaled ability to predict the dynamical evolution of interacting atoms, molecular dynamics (MD) is a widely used computational method in theoretical chemistry, physics, biology, and engineering. Despite its success, MD is only capable of modeling timescales within several orders of magnitude of thermal vibrations, leaving out many important phenomena that occur at slower rates. The temperature-accelerated dynamics (TAD) method overcomes this limitation by thermally accelerating the state-to-state evolution captured by MD. Due to the algorithmically complex nature of the serial TAD procedure, implementations have yet to improve performance by parallelizing the concurrent exploration of multiple states. Here we utilize a discrete-event-based application simulator to introduce and explore a new speculatively parallel TAD (SpecTAD) method. We investigate the SpecTAD algorithm, without a full-scale implementation, by constructing an application simulator proxy (SpecTADSim). Following this method, we discover that a non-trivial relationship exists between the optimal SpecTAD parameter set and the number of CPU cores available at run-time. Furthermore, we find that a majority of the available SpecTAD boost can be achieved within an existing TAD application using relatively simple algorithm modifications.

scholarly journals Repairing and mechanising the JavaScript relaxed memory model

2020 ◽  
Author(s):  
Conrad Watt ◽  
Christopher Pulte ◽  
Anton Podkopaev ◽  
Guillaume Barbier ◽  
Stephen Dolan ◽  
...  
Keyword(s):  
Memory Model ◽  
Relaxed Memory Model ◽  
Relaxed Memory

scholarly journals Using PRRSV-Resilient Sows Improve Performance in Endemic Infected Farms with Recurrent Outbreaks

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 740
Author(s):  
Gloria Abella ◽  
Adela Pagès-Bernaus ◽  
Joan Estany ◽  
Ramona Natacha Pena ◽  
Lorenzo Fraile ◽  
...  
Keyword(s):  
Simulation Model ◽  
Production Cost ◽  
Discrete Event ◽  
Reproductive Parameters ◽  
Productive Performance ◽  
Improve Performance ◽  
Gross Margin ◽  
Event Based ◽  
Improve Disease Control ◽  
Selection Of

The selection of porcine reproductive and respiratory syndrome (PRRS) resilient sows has been proposed as a strategy to control this disease. A discrete event-based simulation model was developed to mimic the outcome of farms with resilient or susceptible sows suffering recurrent PRRSV outbreaks. Records of both phenotypes were registered in a PRRSV-positive farm of 1500 sows during three years. The information was split in the whole period of observation to include a PRRSV outbreak that lasted 24 weeks (endemic/epidemic or En/Ep) or only the endemic phase (En). Twenty simulations were modeled for each farm: Resilient/En, Resilient/En_Ep, Susceptible/En, and Susceptible/En_Ep during twelve years and analyzed for the productive performance and economic outcome, using reference values. The reproductive parameters were generally better for resilient than for susceptible sows in the PRRSV En/Ep scenario, and the contrary was observed in the endemic case. The piglet production cost was always lower for resilient than for susceptible sows but showed only significant differences in the PRRSV En/Ep scenario. Finally, the annual gross margin by sow is significantly better for resilient than for susceptible sows for the PRRSV endemic (12%) and endemic/epidemic scenarios (17%). Thus, the selection of PRRSV resilient sows is a profitable approach for producers to improve disease control.

scholarly journals Relevance of a Sprint Interval Swim Training Set to the 100‐Meter Freestyle Event Based on Blood Lactate and Kinematic Variables

2021 ◽  
Vol 80 (1) ◽  
pp. 153-161
Author(s):  
Elissavet Terzi ◽  
Ariadni Skari ◽  
Stefanos Nikolaidis ◽  
Konstantinos Papadimitriou ◽  
Athanasios Kabasakalis ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Interval Training ◽  
Stroke Index ◽  
Training Set ◽  
Improve Performance ◽  
Training Experience ◽  
Performance Variables ◽  
Measured Speed ◽  
Event Based ◽  
Competitive Swimmers

Abstract Sprint interval training (SIT) sets are commonly used by coaches in the training routine of swimmers competing in short-distance events; however, data regarding their relevance to competitive events are scarce. The aim of this study was to examine whether performance variables differed or correlated between a 4 × 50-m maximal swimming set (with a work-to-rest ratio of 1:4) and the 100-m freestyle event. Eleven male and 16 female competitive swimmers aged 16.1 ± 1.1 years participated in the study. All swimmers trained at least six times a week and had training experience of more than 4 years. They completed the two freestyle tests on different days, in random and counterbalanced order. In each test, speed, blood lactate, stroke rate (SR), and stroke index (SI) were measured. Speed, blood lactate, and SR were higher at the 4 × 50 m compared to the 100 m and were positively correlated between tests (p < 0.001). The SI did not differ significantly, but was positively correlated between tests. Males were faster and had a higher SI than females, but genders did not differ in lactate. Since performance variables were better in the SIT set and correlated with those in the 100-m bout, we suggest that the 4 × 50-m set can be used to improve performance in the 100-m freestyle event. Moreover, this set can help coaches identify which swimmers will swim fastest in the event.

scholarly journals A Verification Framework for Assembly Programs Under Relaxed Memory Model Using SMT Solver

2018 ◽  
Vol E101.D (12) ◽  
pp. 3038-3058
Author(s):  
Pattaravut MALEEHUAN ◽  
Yuki CHIBA ◽  
Toshiaki AOKI
Keyword(s):  
Memory Model ◽  
Smt Solver ◽  
Relaxed Memory Model ◽  
Relaxed Memory

Replication of the Superstition and Performance Study by

2014 ◽  
Vol 45 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Robert J. Calin-Jageman ◽  
Tracy L. Caldwell
Keyword(s):  
Task Difficulty ◽  
Statistical Power ◽  
Meta Analysis ◽  
A Priori ◽  
Significant Heterogeneity ◽  
Performance Study ◽  
Improve Performance ◽  
Research Designs ◽  
Series Of Experiments ◽  
And Performance

A recent series of experiments suggests that fostering superstitions can substantially improve performance on a variety of motor and cognitive tasks ( Damisch, Stoberock, & Mussweiler, 2010 ). We conducted two high-powered and precise replications of one of these experiments, examining if telling participants they had a lucky golf ball could improve their performance on a 10-shot golf task relative to controls. We found that the effect of superstition on performance is elusive: Participants told they had a lucky ball performed almost identically to controls. Our failure to replicate the target study was not due to lack of impact, lack of statistical power, differences in task difficulty, nor differences in participant belief in luck. A meta-analysis indicates significant heterogeneity in the effect of superstition on performance. This could be due to an unknown moderator, but no effect was observed among the studies with the strongest research designs (e.g., high power, a priori sampling plan).

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