Synergistic Server-Based Network Processing Stack

Network functions provide the required functionality to interconnect systems while ensuring security, availability, efficiency, and performance. With the recent trend to run network functions in software over commodity servers (instead of using specialized appliances), there is the need to introduce new systems that can provide the required network features while running on top of optimal processing environments. Several software packet processing technologies currently exist (e.g., in-kernel/kernel-bypass, XDP, and SmartNICs) and each of them provide different features in terms of available functionality, processing capabilities, performance, and efficiency. In this thesis, we break down network application processing needs and by characterizing the processing features provided by each technology, we verify that no single technology can cover all network application requirements. With this observation, we provide new systems that often break the boundaries between different technologies, allowing the building of optimal packet processing environments that can meet countless requirements of modern networks. Using this as the foundation of our work, we build systems to address many network function needs &ndash; layer 2 to layer 7 processing and monitoring. In our first work, we introduce a new packet I/O subsystem to a high-performance userspace TCP stack. This subsystem is provided by new programmable in-kernel features allowing the TCP stack to have a better resource consumption profile and to build cooperation mechanisms between the kernel and userspace. In our second work, we address the needs of monitoring systems by introducing new primitives that allow for building high-coverage monitoring systems with high performance and efficiency. We optimize those primitives by building an efficient division of work between SmartNIC offloads, XDP on the host, and userspace processing. Finally, in our third work, we rethink the Linux networking stack to address the inneficiencies that prevent it to support the performance requirements of modern applications. We propose to break down its processing in a minimal and efficient fast path and a in a robust and feature-rich slow path provided by the Linux kernel. The fast path is built on demand, based on current processing needs for a given set of services configuration and gets assistance from the slow path for processing completeness. This allows avoiding unnecessary processing inside the kernel, minimizing overheads and increasing performance, while still maintaining Linux&rsquo;s rich set of features. With these contributions, we believe that we can provide new foundations to help both academia and industry to build optimized systems that can address many modern network needs.</p

An algorithm based on response time and traffic demands to scale containers on a cloud computing system

Este trabalho propõe uma arquitetura de computação em nuvem baseada em containers e um algoritmo de auto elasticidade. O algoritmo promove a otimização do processamento das requisições por meio da alocação eficiente do número de containers para alcançar tempos esperados de resposta no processamento de requisições. Para avaliar arquitetura proposta foi utilizada uma carga de trabalho caracterizada com base em uma série temporal real resultante das requisições de um sistema Web da Controladoria Geral da União (CGU). O sistema foi submetido a diferentes testes de carga e os resultados mostram que a solução proposta apresenta um forte potencial dado que consegue cumprir os requerimentos de desempenho alocando containers de forma mais eficiente do que outras propostas

Analysis of risk factors associated with cerebral angiography headache

Background Despite previous studies indicating a moderate/high incidence of angiography headache (AH), there is still limited data about the risk factors associated with its occurrence. Objective The present study aimed to assess the associations among demographic, clinical, and technical characteristics of cerebral digital subtraction angiography (DSA) and the occurrence of AH. Methods Cross-sectional analytical observational study with a sample comprised of individuals with a recommendation for elective DSA. Clinical interviews were conducted to assess the occurrence of AH, using a standardized questionnaire. Results Among 114 subjects, the mean age was 52.8 (±13.8) years old, 75.4% (86/114) were women, 29.8% (34/114) had a history of migraines, and 10.5% (12/114) had chronic headaches. The overall frequency of AH was 45.6% (52/114). Of those, 88.4% (46/52) underwent 3D angiography, 7.7% (4/52) underwent aortography, and 1.9% (1/52) underwent both procedures. There was a statistically significant association between AH and previous history of migraine (odds ratio [OR]: 4.9; 95% confidence interval [CI] 1.62–14.7; p = 0.005) and 3D angiography (OR 6.62; 95%CI: 2.04–21.5; p = 0.002). Conclusions 3D angiography is strongly associated with the occurrence of AH, which has never been reported before. The association between a previous history of migraine and AH confirms the results of previous studies

Why do presidents fail? political leadership and the Argentine crisis (1999–2001)

This article explores why Argentine president Fernando de la Rúa (1999–2001) failed to govern and the factors that prevented him from completing his constitutional mandate. This study draw on current literature about leadership. We argue that President De la Rúa’s ineffective performance was characteristic of an inflexible tendency towards unilateralism, isolationism, and an inability to compromise and persuade. Moreover, we examine how de la Rúas performance, in the context of severe political and economic constraints, discouraged cooperative practices among political actors, led to decision-making paralysis, and ultimately to a crisis of governance.This work seeks to make four contributions. First, it conceptualizes political leadership by providing an analytical framework that integrates individual action, institutional resources and constraints, and policy context, thus filling a gap in the literature. Second, it explains the importance of effective leadership in building up and maintaining multiparty coalitions in presidential systems. Third, it complements existing institutional approaches to improve our understanding of a new type of instability in Latin America: the failure of more than a dozen of presidents to complete their constitutional mandates. Fourth, it analyzes the way political and economic variables interact in times of crisis

Opinião pública e política externa do Brasil do Império a João Goulart: um balanço historiográfico

Este artigo avalia a relação existente entre opinião pública e política externa no Brasil, desde o Império, em que se evidenciam os interesses das elites letradas enunciados no Parlamento, até a presidência de Jânio Quadros, quando se verifica o apogeu do populismo no Brasil. Procura estabelecer quais eram as correntes de opinião expressa que representavam a política externa nos diversos períodos da historiografia brasileira de relações internacionais. Pretende, também, avaliar a extensão da repercussão que teria a política internacional brasileira sobre a opinião nacional no mesmo período.<br>The purpose of this article is to evaluate the rapport between public opinion and Brazilian foreign policy. It proposes a historiographic analysis of the period going from the country's independence to the apogee of populism under João Goulart's presidency. It also aims to determine the groups which most evidently represented public opinion in the various periods of Brazilian history of international relations, as well as the importance of their expressed points of view in relation to the foreign policy decision-making process. Also pertinent is the comprehension of the impact which international relations may have had in society in the same period