rOpenCL: uma ferramenta para acesso de aplicações heterogéneas a co-processadores remotos

Há cerca de uma década, o panorama da arquitetura dos sistemas de computação registou um salto evolutivo, com o aparecimento de sistemas heterogéneos. Nestes sistemas, à unidade central de processamento (CPU), talhada para uso genérico, juntaram-se dispositivos co-processadores, como GPUs e FPGAs, de diferentes arquiteturas. Originalmente concebidos para fins muito específicos (como processamento gráfico ou de sinal), estes coprocessadores passaram a ser vistos como elementos auxiliares de processamento, capazes de acelerar a execução de aplicações computacionalmente exigentes. Para permitir a exploração eficiente de sistemas heterogéneos, e garantir portabilidade do código, definiram-se standards abertos, como o OpenCL, suportando co-processadores de virtualmente qualquer tipo. Noutros casos, passaram a existir frameworks proprietárias, orientadas a dispositivos de fabricantes específicos, como a framework CUDA para GPUs da NVIDIA. Comum a todas estas abordagens é o facto de, originalmente, apenas preverem a utilização de co-processadores locais, ligados a um único sistema hospedeiro, não possibilitando a exploração de aceleradores ligados a outros sistemas, acessíveis via rede, limitando assim o potencial de aceleração das aplicações. O trabalho desenvolvido nesta dissertação dá resposta a esta limitação. Consistiu na criação do remote OpenCL (rOpenCL), middleware e serviços que, em conjunto, permitem que uma aplicação OpenCL (mesmo pré-compilada), explore de forma transparente e eficiente o conjunto de aceleradores disponíveis num ambiente distribuído de sistemas Linux, recorrendo a comunicação portável assente em sockets BSD. A abordagem é validada recorrendo a benchmarks OpenCL de referência, que provam a conformidade do rOpenCL com a especificação OpenCL 1.2, bem como a robustez e escalabilidade da implementação.About a decade ago, the landscape of computer systems architecture registered an evolutionary leap, with the appearance of heterogeneous systems. In these systems, the central processing unit (CPU), designed for generic use, was joined by co-processor devices, such as GPUS and FPGAS, of different architectures. Originally designed for very specific purposes (such as graphic or signal processing), these co-processors came to be seen as auxiliary processing elements, capable of accelerating the execution of computationally demanding applications. To allow efficient exploitation of heterogeneous systems, and to ensure portability of code, open standards were defined, such as OpenCL, supporting coprocessors of virtually any type. In other cases, there have been proprietary frameworks oriented to devices from specific manufacturers, such as the CUDA framework for NVIDIA GPUs. Common to all these approaches is that they originally only provide for the use of local co-processors, which are connected to a single host system, and do not allow the exploitation of accelerators connected to other systems, accessible via the network, thereby limiting the potential for application acceleration. The work developed in this dissertation responds to this limitation. It consisted of the creation of remote OpenCL (rOpenCL), middleware and services that allow an OpenCL application (even pre-compiled) to transparently and efficiently explore the set of accelerators available in a distributed Linux system environment, using portable BSD sockets for communication. The approach is validated using reference OpenCL benchmarks, which prove the rOpenCL compliance with the OpenCL 1.2 specification, as well as the robustness and scalability of the implementation

clOpenCLip - Estendendo aplicações heterogéneas a ambientes distribuí­dos de forma transparente

Em sistemas computacionais heterogéneos co-existem dispositivos de computação de diferentes arquiteturas, além da principal (hospedeira). Para tirar partido dessa variedade, com o objetivo de acelerar a sua execução, as aplicações desdobram-se em componentes de código destinados aos diferentes dispositivos disponíveis. Um dos principais modelos de programação deste tipo de aplicações é o OpenCL, modelo aberto e independente, dos fabricantes de hardware. No modelo aplicacional original do OpenCL, uma “aplicação heterogénea” arranca num certo nó hospedeiro, podendo recorrer aos vários dispositivos de computação locais. No entanto, o modelo não permite utilizar dispositivos de outros nós, ainda que interligados em rede com o nó de arranque. O clOpenCLip (cluster OpenCL sobre IP), apresentado neste poster, pretende resolver este problema. O objetivo deste trabalho é a construção de uma solução que possibilite o uso dos múltiplos dispositivos de computação disponíveis num ambiente distribuído, por parte de aplicações que seguem o modelo OpenCL, utilizando comunicação baseada em TCP/IP, e de forma completamente transparente, ou seja, compatível com aplicações OpenCL já pré-compiladas. A agregação dos vários dispositivos de computação disponíveis em ambiente distribuído foi realizada através de um conjunto de serviços que intermedeiam a submissão de pedidos de clientes remotos aos dispositivos co-localizados com os serviços, sendo toda a comunicação cliente-servidor baseada em sockets BSD (sobre UDP ou TCP). Nos clientes, um novo driver OpenCL expõe todos os dispositivos remotos disponíveis e fornece às aplicações a transparência necessária para a exploração desses dispositivos. No estágio atual de desenvolvimento, o clOpenCLip foi já validado com recurso a um conjunto diversificado de benchmarks OpenCL, que permitiram por à prova a estabilidade da implementação e aferir o impacto da comunicação no desempenho. Os objetivos iniciais estão praticamente atingidos, uma vez que já é possível a execução de funções OpenCL em sistemas remotos. Além disso, um grande número de primitivas OpenCL 1.2 já está abrangida no clOpenCLip, o que aumenta o seu potencial de uso. Apesar disso, e de toda a validação já feita através de um vasto conjunto de benchmarks OpenCL, ainda existem aspetos que é necessário considerar: validar a robustez da troca de mensagens quando o protocolo de comunicação escolhido é o UDP; tentar alargar a 100% o grau de cobertura da especificação OpenCL1.2; optimizar o código produzido, de forma a minimizar o mais possível o impacto da comunicação em rede e do processamento das mensagens trocadas; realizar benchmarks com vários clientes interagindo com os mesmos serviços, para validar a robustez destes e estudar a sua escalabilidade.info:eu-repo/semantics/publishedVersio

Controlador de presenças para ambiente Windows

Nos dias de hoje, o controlo de presenças é um mecanismo indispensável na maioria das empresas. A solução destina-se a quantificar o tempo de trabalho dos colaboradores cujas funções sejam desempenhadas com recurso a um computador. O controlador afere o tempo de trabalho, dos colaborados, através do tempo efetivo de utilização das ferramentas de trabalho. Numa primeira fase, os eventos capturados são armazenados localmente, para posteriormente, serem enviados para uma base de dados central onde são processados.info:eu-repo/semantics/publishedVersio

Controlador de presenças

Nowadays, presence control is a widespread mechanism used by companies as a way to ensure that their associates provide regular output, or to determine the pay check in relation to reported work hours. This work under development aims to conceive and implement ways to monitor desktop-based working hours of associates, especially those who do not need to be at the workplace to perform their tasks or those with a flexible work schedule. This solution validates the desk-time based on the time spent on desktop tools. Furthermore, it includes a local database, where the information about the interaction of associates with the system, is at first stored. Then, all data is downloaded to the central control database for further analysis, which is chiefly to identify and categorize behavior patterns. With this work it was possible to test the feasibility of this kind of solution, which has a self-regulating capacity to quantify effective working time of the associates with precision and fairness-based monitoring, while ensuring good privacy policy among the users – the reason why the system only exposes absolute and relative quantitative indicators instead of detailed reports. This work is basic concept for a solution that can bring out innovation by its approach, distinctiveness, and privacy policy, and in practice this solutions can have many more applications, for instance in the area of human resources management and productivity control.info:eu-repo/semantics/publishedVersio

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s\sqrt s = 13 TeV

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s}$ = 7 TeV, as well as with theoretical predictions.[graphic not available: see fulltext]Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s} =$ 7 TeV, as well as with theoretical predictions

Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV

A search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

Azimuthal separation in nearly back-to-back jet topologies in inclusive 2-and 3-jet events in pp collisions at root s=13TeV

A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Delta phi(12), is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 35.9 fb(-1) are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with themeasurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177 degrees <Delta phi(12) <180 degrees. The 2- and 3-jet measurements are not simultaneously described by any of models.Peer reviewe