52 research outputs found
P4-compatible High-level Synthesis of Low Latency 100 Gb/s Streaming Packet Parsers in FPGAs
Packet parsing is a key step in SDN-aware devices. Packet parsers in SDN
networks need to be both reconfigurable and fast, to support the evolving
network protocols and the increasing multi-gigabit data rates. The combination
of packet processing languages with FPGAs seems to be the perfect match for
these requirements. In this work, we develop an open-source FPGA-based
configurable architecture for arbitrary packet parsing to be used in SDN
networks. We generate low latency and high-speed streaming packet parsers
directly from a packet processing program. Our architecture is pipelined and
entirely modeled using templated C++ classes. The pipeline layout is derived
from a parser graph that corresponds a P4 code after a series of graph
transformation rounds. The RTL code is generated from the C++ description using
Xilinx Vivado HLS and synthesized with Xilinx Vivado. Our architecture achieves
100 Gb/s data rate in a Xilinx Virtex-7 FPGA while reducing the latency by 45%
and the LUT usage by 40% compared to the state-of-the-art.Comment: Accepted for publication at the 26th ACM/SIGDA International
Symposium on Field-Programmable Gate Arrays February 25 - 27, 2018 Monterey
Marriott Hotel, Monterey, California, 7 pages, 7 figures, 1 tabl
Module-per-Object: a Human-Driven Methodology for C++-based High-Level Synthesis Design
High-Level Synthesis (HLS) brings FPGAs to audiences previously unfamiliar to
hardware design. However, achieving the highest Quality-of-Results (QoR) with
HLS is still unattainable for most programmers. This requires detailed
knowledge of FPGA architecture and hardware design in order to produce
FPGA-friendly codes. Moreover, these codes are normally in conflict with best
coding practices, which favor code reuse, modularity, and conciseness.
To overcome these limitations, we propose Module-per-Object (MpO), a
human-driven HLS design methodology intended for both hardware designers and
software developers with limited FPGA expertise. MpO exploits modern C++ to
raise the abstraction level while improving QoR, code readability and
modularity. To guide HLS designers, we present the five characteristics of MpO
classes. Each characteristic exploits the power of HLS-supported modern C++
features to build C++-based hardware modules. These characteristics lead to
high-quality software descriptions and efficient hardware generation. We also
present a use case of MpO, where we use C++ as the intermediate language for
FPGA-targeted code generation from P4, a packet processing domain specific
language. The MpO methodology is evaluated using three design experiments: a
packet parser, a flow-based traffic manager, and a digital up-converter. Based
on experiments, we show that MpO can be comparable to hand-written VHDL code
while keeping a high abstraction level, human-readable coding style and
modularity. Compared to traditional C-based HLS design, MpO leads to more
efficient circuit generation, both in terms of performance and resource
utilization. Also, the MpO approach notably improves software quality,
augmenting parametrization while eliminating the incidence of code duplication.Comment: 9 pages. Paper accepted for publication at The 27th IEEE
International Symposium on Field-Programmable Custom Computing Machines, San
Diego CA, April 28 - May 1, 201
Bridging the Gap: FPGAs as Programmable Switches
The emergence of P4, a domain specific language, coupled to PISA, a domain
specific architecture, is revolutionizing the networking field. P4 allows to
describe how packets are processed by a programmable data plane, spanning ASICs
and CPUs, implementing PISA. Because the processing flexibility can be limited
on ASICs, while the CPUs performance for networking tasks lag behind, recent
works have proposed to implement PISA on FPGAs. However, little effort has been
dedicated to analyze whether FPGAs are good candidates to implement PISA. In
this work, we take a step back and evaluate the micro-architecture efficiency
of various PISA blocks. We demonstrate, supported by a theoretical and
experimental analysis, that the performance of a few PISA blocks is severely
limited by the current FPGA architectures. Specifically, we show that match
tables and programmable packet schedulers represent the main performance
bottlenecks for FPGA-based programmable switches. Thus, we explore two avenues
to alleviate these shortcomings. First, we identify network applications well
tailored to current FPGAs. Second, to support a wider range of networking
applications, we propose modifications to the FPGA architectures which can also
be of interest out of the networking field.Comment: To be published in : IEEE International Conference on High
Performance Switching and Routing 202
Caracterização quĂmica e avaliação das atividades antibacteriana, antifĂşngica, antimicobacteriana e citotĂłxica de Talinum paniculatum
In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteus and Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosisand Mycobacterium bovisas well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatumshowed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.Neste estudo foi avaliada a bioatividade de Talinum paniculatum, planta amplamente utilizada na medicina popular. O extrato das folhas (EF) de T. paniculatum foi obtido por percolação com etanol-água e, em seguida, submetido Ă partição lĂquido-lĂquido, obtendo-se as frações hexânica (HX), acetato-etĂlica (AcOEt), butanĂłlica (BuOH) e aquosa (Aq). A triagem para a atividade antimicrobiana do EF e de suas frações foram avaliadas in vitro atravĂ©s do mĂ©todo de microdiluição em caldo contra treze micro-organismos patogĂŞnicos e nĂŁo-patogĂŞnicos e, a atividade antimicobacteriana, foi avaliada atravĂ©s do teste de difusĂŁo em ágar. As concentrações citotĂłxicas (CC90) do EF e das frações HX e AcOEt foram obtidas sobre cĂ©lulas da linhagem BHK-21 atravĂ©s do ensaio de redução do MTT. O EF mostrou atividade contra Serratia marcescens e Staphylococcus aureus, com valores de concentração inibitĂłria mĂnima (CIM) de 250 e 500 µg/mL, respectivamente. AlĂ©m disso, HX demonstrou excelente atividade contra Micrococcus luteus e Candida albicans com uma CIM de 31,2 µg/mL, em ambos os casos. Contra Escherichia coli, a CIM para AcOEt foi tambĂ©m de 31,2 µg/mL. Por outro lado, as frações BuOH e Aq foram inativas contra todos os micro-organismos testados, assim como o EF contra Mycobacterium tuberculosis e Mycobacterium bovis. Campesterol, estigmasterol e sitosterol foram as estruturas propostas como principais compostos presentes no EF e nas frações HX e AcOEt, evidenciadas atravĂ©s de espectrometria de massas. Portanto, o extrato da folha e as frações HX e AcOEt provenientes de T. paniculatum apresentaram potencial como possĂveis fontes de compostos antimicrobianos, HX principalmente, por ter apresentado uma baixa toxicidade sobre cĂ©lulas BHK-21 com um bom Ăndice de seletividade (IS = CC90/MIC) de 17,72 contra C. albicans
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
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