MorphoSys: efficient colocation of QoS-constrained workloads in the cloud

In hosting environments such as IaaS clouds, desirable application performance is usually guaranteed through the use of Service Level Agreements (SLAs), which specify minimal fractions of resource capacities that must be allocated for unencumbered use for proper operation. Arbitrary colocation of applications with different SLAs on a single host may result in inefficient utilization of the host’s resources. In this paper, we propose that periodic resource allocation and consumption models -- often used to characterize real-time workloads -- be used for a more granular expression of SLAs. Our proposed SLA model has the salient feature that it exposes flexibilities that enable the infrastructure provider to safely transform SLAs from one form to another for the purpose of achieving more efficient colocation. Towards that goal, we present MORPHOSYS: a framework for a service that allows the manipulation of SLAs to enable efficient colocation of arbitrary workloads in a dynamic setting. We present results from extensive trace-driven simulations of colocated Video-on-Demand servers in a cloud setting. These results show that potentially-significant reduction in wasted resources (by as much as 60%) are possible using MORPHOSYS.National Science Foundation (0720604, 0735974, 0820138, 0952145, 1012798

Dynamic Window-Constrained Scheduling for Real-Time Media Streaming

This paper describes an algorithm for scheduling packets in real-time multimedia data streams. Common to these classes of data streams are service constraints in terms of bandwidth and delay. However, it is typical for real-time multimedia streams to tolerate bounded delay variations and, in some cases, finite losses of packets. We have therefore developed a scheduling algorithm that assumes streams have window-constraints on groups of consecutive packet deadlines. A window-constraint defines the number of packet deadlines that can be missed in a window of deadlines for consecutive packets in a stream. Our algorithm, called Dynamic Window-Constrained Scheduling (DWCS), attempts to guarantee no more than x out of a window of y deadlines are missed for consecutive packets in real-time and multimedia streams. Using DWCS, the delay of service to real-time streams is bounded even when the scheduler is overloaded. Moreover, DWCS is capable of ensuring independent delay bounds on streams, while at the same time guaranteeing minimum bandwidth utilizations over tunable and finite windows of time. We show the conditions under which the total demand for link bandwidth by a set of real-time (i.e., window-constrained) streams can exceed 100% and still ensure all window-constraints are met. In fact, we show how it is possible to guarantee worst-case per-stream bandwidth and delay constraints while utilizing all available link capacity. Finally, we show how best-effort packets can be serviced with fast response time, in the presence of window-constrained traffic

MORPHOSYS: efficient colocation of QoS-constrained workloads in the cloud

In hosting environments such as IaaS clouds, desirable application performance is usually guaranteed through the use of Service Level Agreements (SLAs), which specify minimal fractions of resource capacities that must be allocated for use for proper operation. Arbitrary colocation of applications with different SLAs on a single host may result in inefficient utilization of the host’s resources. In this paper, we propose that periodic resource allocation and consumption models be used for a more granular expression of SLAs. Our proposed SLA model has the salient feature that it exposes flexibilities that enable the IaaS provider to safely transform SLAs from one form to another for the purpose of achieving more efficient colocation. Towards that goal, we present MorphoSys: a framework for a service that allows the manipulation of SLAs to enable efficient colocation of workloads. We present results from extensive trace-driven simulations of colocated Video-on-Demand servers in a cloud setting. The results show that potentially-significant reduction in wasted resources (by as much as 60%) are possible using MorphoSys.First author draf

Modelação e simulação de equipamentos de rede para Indústria 4.0

Currently, the industrial sector has increasingly opted for digital technologies in order to automate all its processes. This development comes from notions like Industry 4.0 that redefines the way these systems are designed. Structurally, all the components of these systems are connected in a complex network known as the Industrial Internet of Things. Certain requirements arise from this concept regarding industrial communication networks. Among them, the need to ensure real-time communications, as well as support for dynamic resource management, are extremely relevant. Several research lines pursued to develop network technologies capable of meeting such requirements. One of these protocols is the Hard Real-Time Ethernet Switch (HaRTES), an Ethernet switch with support for real-time communications and dynamic resource management, requirements imposed by Industry 4.0. The process of designing and implementing industrial networks can, however, be quite time consuming and costly. These aspects impose limitations on testing large networks, whose level of complexity is higher and requires the usage of more hardware. The utilization of network simulators stems from the necessity to overcome such restrictions and provide tools to facilitate the development of new protocols and evaluation of communications networks. In the scope of this dissertation a HaRTES switch model was developed in the OMNeT++ simulation environment. In order to demonstrate a solution that can be employed in industrial real-time networks, this dissertation presents the fundamental aspects of the implemented model as well as a set of experiments that compare it with an existing laboratory prototype, with the objective of validating its implementation.Atualmente o setor industrial tem vindo cada vez mais a optar por tecnologias digitais de forma a automatizar todos os seus processos. Este desenvolvimento surge de noções como Indústria 4.0, que redefine o modo de como estes sistemas são projetados. Estruturalmente, todos os componentes destes sistemas encontram-se conectados numa rede complexa conhecida como Internet Industrial das Coisas. Certos requisitos advêm deste conceito, no que toca às redes de comunicação industriais, entre os quais se destacam a necessidade de garantir comunicações tempo-real bem como suporte a uma gestão dinâmica dos recursos, os quais são de extrema importância. Várias linhas de investigação procuraram desenvolver tecnologias de rede capazes de satisfazer tais exigências. Uma destas soluções é o "Hard Real-Time Ethernet Switch" (HaRTES), um switch Ethernet com suporte a comunicações de tempo-real e gestão dinâmica de Qualidade-de-Serviço (QoS), requisitos impostos pela Indústria 4.0. O processo de projeto e implementação de redes industriais pode, no entanto, ser bastante moroso e dispendioso. Tais aspetos impõem limitações no teste de redes de largas dimensões, cujo nível de complexidade é mais elevado e requer o uso de mais hardware. Os simuladores de redes permitem atenuar o impacto de tais limitações, disponibilizando ferramentas que facilitam o desenvolvimento de novos protocolos e a avaliação de redes de comunicações. No âmbito desta dissertação desenvolveu-se um modelo do switch HaRTES no ambiente de simulação OMNeT++. Com um objetivo de demonstrar uma solução que possa ser utilizada em redes de tempo-real industriais, esta dissertação apresenta os aspetos fundamentais do modelo implementado bem como um conjunto de experiências que o comparam com um protótipo laboratorial já existente, no âmbito da sua validação.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Design and analysis of stream scheduling algorithms in distributed reservation-based multimedia systems

Ph.DDOCTOR OF PHILOSOPH

Congestion Control for Streaming Media

The Internet has assumed the role of the underlying communication network for applications such as file transfer, electronic mail, Web browsing and multimedia streaming. Multimedia streaming, in particular, is growing with the growth in power and connectivity of today\u27s computers. These Internet applications have a variety of network service requirements and traffic characteristics, which presents new challenges to the single best-effort service of today\u27s Internet. TCP, the de facto Internet transport protocol, has been successful in satisfying the needs of traditional Internet applications, but fails to satisfy the increasingly popular delay sensitive multimedia applications. Streaming applications often use UDP without a proper congestion avoidance mechanisms, threatening the well-being of the Internet. This dissertation presents an IP router traffic management mechanism, referred to as Crimson, that can be seamlessly deployed in the current Internet to protect well-behaving traffic from misbehaving traffic and support Quality of Service (QoS) requirements of delay sensitive multimedia applications as well as traditional Internet applications. In addition, as a means to enhance Internet support for multimedia streaming, this dissertation report presents design and evaluation of a TCP-Friendly and streaming-friendly transport protocol called the Multimedia Transport Protocol (MTP). Through a simulation study this report shows the Crimson network efficiently handles network congestion and minimizes queuing delay while providing affordable fairness protection from misbehaving flows over a wide range of traffic conditions. In addition, our results show that MTP offers streaming performance comparable to that provided by UDP, while doing so under a TCP-Friendly rate