Muistikeskeisen radioverkon vaikutus tietopääsyjen suoritusnopeuteen

Future 5G-based mobile networks will be largely defined by virtualized network functions (VNF). The related computing is being moved to cloud where a set of servers is provided to run all the software components of the VNFs. Such software component can be run on any server in the mobile network cloud infrastructure. The servers conventionally communicate via TCP/IP -network. To realize planned low-latency use cases in 5G, some servers are placed to data centers near the end users (edge clouds). Many of these use cases involve data accesses from one VNF to another, or to other network elements. The accesses are desired to take as little time as possible to stay within the stringent latency requirements of the new use cases. As a possible approach for reaching this, a novel memory-centric platform was studied. The main ideas of the memory-centric platform are to collapse the hierarchy between volatile and persistent memory by utilizing non-volatile memory (NVM) and use memory-semantic communication between computer components. In this work, a surrogate memory-centric platform was set up as a storage for VNFs and the latency of data accesses from VNF application was measured in different experiments. Measurements against a current platform showed that memory-centric platform was significantly faster to access than the current, TCP/IP using platform. Measurements for accessing RAM with different memory bandwidths within the memory-centric platform showed that the order of latency was roughly independent of the available memory bandwidth. These results mean that memory-centric platform is a promising alternative to be used as a storage system for edge clouds. However, more research is needed to study how other service qualities, such as low latency variation, are fulfilled in memory-centric platform in a VNF environment.Tulevaisuuden 5G:hen perustuvissa mobiiliverkoissa verkkolaitteisto on pääosin virtualisoitu. Tällaisen verkon virtuaaliverkkolaite (VNF) koostuu ohjelmistokomponenteista, joita ajetaan tarkoitukseen määrätyiltä mobiiliverkon pilven palvelimilta. Ohjelmistokomponentti voi olla ajossa millä vain mobiiliverkon näistä pilvi-infrastruktuurin palvelimista. Palvelimet on tavallisesti yhdistetty TCP/IP-verkolla. Jotta suunnitellut alhaisen viiveen käyttötapaukset voisivat toteutua 5G-verkoissa, pilvipalvelimia on sijoitettu niin kutsuttuihin reunadatakeskuksiin lähelle loppukäyttäjiä. Monet näistä käyttötapauksista sisältävät tietopääsyjä virtuaaliverkkolaitteesta toisiin tai muihin verkkoelementteihin. Tietopääsyviiveen halutaan olevan mahdollisimman pieni, jotta käyttötapausten tiukoissa viiverajoissa pysytään. Mahdollisena lähestymistapana tietopääsyviiveen minimoimiseen tutkittiin muistikeskeistä laitteistoalustaa. Tämän laitteistoalustan pääperiaatteita on korvata nykyiset lyhytkestoiset ja pysyvät muistit haihtumattomalla muistilla sekä kommunikoida muistisemanttisilla viesteillä tietokonekomponenttien kesken. Tässä työssä muistikeskeisyyttä hyödyntävää sijaislaitteistoa käytettiin VNF-datan varastona ja ohjelmistokomponenttien tietopääsyviivettä sinne mitattiin erilaisilla kokeilla. Kokeet osoittivat nykyisen, TCP/IP-pohjaisen alustan huomattavasti muistikeskeistä alustaa hitaammaksi. Toiseksi, kokeet osoittivat tietopääsyviiveiden olevan saman suuruisia muistikeskeisen alustan sisällä, riippumatta saatavilla olevasta muistikaistasta. Tulokset merkitsevät, että muistikeskeinen alusta on lupaava vaihtoehto reunadatakeskuksen tietovarastojärjestelmäksi. Lisää tutkimusta alustasta kuitenkin tarvitaan, jotta muiden palvelun laatukriteerien, kuten matalan viivevaihtelun, toteutumisesta saadaan tietoa

Clustering Techniques : A solution for e-business

The purpose of this thesis was to provide the best clustering solution for the Archipelago web site project which would have been part of the Central Baltic Intereg IV programme 2007-2013. The entire program is a merger between the central Baltic regions of Finland, including the Åland Islands, Sweden and Estonia. A literature review of articles and research on various clustering techniques for the different sections of the project led to the findings of this document. Clustering was needed for web servers and the underlying database implementation. Additionally, the operating system used for all servers in both sections was required to present the best clustering solution. Implementing OSI layer 7 clustering for the web server cluster, MySQL database clustering and using Linux operating system would have provided the best solution for the Archipelago website. This implementation would have provided unlimited scalability, availability and high performance for the web site. Also, it is the most cost effective solution because it would utilize the commodity hardware

Architecture independent environment for developing engineering software on MIMD computers

Engineers are constantly faced with solving problems of increasing complexity and detail. Multiple Instruction stream Multiple Data stream (MIMD) computers have been developed to overcome the performance limitations of serial computers. The hardware architectures of MIMD computers vary considerably and are much more sophisticated than serial computers. Developing large scale software for a variety of MIMD computers is difficult and expensive. There is a need to provide tools that facilitate programming these machines. First, the issues that must be considered to develop those tools are examined. The two main areas of concern were architecture independence and data management. Architecture independent software facilitates software portability and improves the longevity and utility of the software product. It provides some form of insurance for the investment of time and effort that goes into developing the software. The management of data is a crucial aspect of solving large engineering problems. It must be considered in light of the new hardware organizations that are available. Second, the functional design and implementation of a software environment that facilitates developing architecture independent software for large engineering applications are described. The topics of discussion include: a description of the model that supports the development of architecture independent software; identifying and exploiting concurrency within the application program; data coherence; engineering data base and memory management

A transputer based parallel database system.

A sophisticated database application generation environment known as DB4GL has been developed at Sheffield City Polytechnic. A unique feature of DB4GL is the object-oriented application model used to specify and generate database applications. Although DB4GL has many advanced and powerful features, such as a self-describing data dictionary and extensive integrity rule processing facilities; the system has not been designed for high performance in either the generation tools or the generated database applications. The Parallel-DB4GL (P-DB4GL) project represents an attempt to improve the performance of the generated database applications, by constructing a new concurrent implementation of DB4GL for execution on transputer-based parallel hardware. This thesis describes the DB4GL system as developed to the commencement of the P-DB4GL project. A prototype P-DB4GL system has been implemented that demonstrates how significant performance gains can be obtained from a concurrent implementation on transputer-based parallel hardware. Based on the successful results of this prototype system, designs for a fully functional multiprocessor P-DB4GL system are proposed. The details of this prototype and the fully functional designs are presented in this thesis. The thesis also provides an evaluation of the P-DB4GL project as a whole, and concludes with some suggestions for further research in the areas of parallel databases and object-oriented system implementation

A technology reference model for client/server software development

In today's highly competitive global economy, information resources representing enterprise-wide information are essential to the survival of an organization. The development of and increase in the use of personal computers and data communication networks are supporting or, in many cases, replacing the traditional computer mainstay of corporations. The client/server model incorporates mainframe programming with desktop applications on personal computers. The aim of the research is to compile a technology model for the development of client/server software. A comprehensive overview of the individual components of the client/server system is given. The different methodologies, tools and techniques that can be used are reviewed, as well as client/server-specific design issues. The research is intended to create a road map in the form of a Technology Reference Model for Client/Server Software Development.ComputingM. Sc. (Information Systems

Storage Area Networks

This tutorial compares Storage area Network (SAN) technology with previous storage management solutions with particular attention to promised benefits of scalability, interoperability, and high-speed LAN-free backups. The paper provides an overview of what SANs are, why invest in them, and how SANs can be managed. The paper also discusses a primary management concern, the interoperability of vendor-specific SAN solutions. Bluefin, a storage management interface and interoperability solution is also explained. The paper concludes with discussion of SAN-related trends and implications for practice and research

Distributed databases

Mòdul 3 del llibre Database Architecture. UOC, 20122022/202

High Performance Transaction Processing on Non-Uniform Hardware Topologies

Transaction processing is a mission critical enterprise application that runs on high-end servers. Traditionally, transaction processing systems have been designed for uniform core-to-core communication latencies. In the past decade, with the emergence of multisocket multicores, for the first time we have Islands, i.e., groups of cores that communicate fast among themselves and slower with other groups. In current mainstream servers, each multicore processor corresponds to an Island. As the number of cores on a chip increases, however, we expect that multiple Islands will form within a single processor in the nearby future. In addition, the access latencies to the local memory and to the memory of another server over fast interconnect are converging, thus creating a hierarchy of Islands within a group of servers. Non-uniform hardware topologies pose a significant challenge to the scalability and the predictability of performance of transaction processing systems. Distributed transaction processing systems can alleviate this problem; however, no single deployment configuration is optimal for all workloads and hardware topologies. In order to fully utilize the available processing power, a transaction processing system needs to adapt to the underlying hardware topology and tune its configuration to the current workload. More specifically, the system should be able to detect any changes to the workload and hardware topology, and adapt accordingly without disrupting the processing. In this thesis, we first systematically quantify the impact of hardware Islands on deployment configurations of distributed transaction processing systems. We show that none of these configurations is optimal for all workloads, and the choice of the optimal configuration depends on the combination of the workload and hardware topology. In the cluster setting, on the other hand, the choice of optimal configuration additionally depends on the properties of the communication channel between the servers. We address this challenge by designing a dynamic shared-everything system that adapts its data structures automatically to hardware Islands. To ensure good performance in the presence of shifting workload patterns, we use a lightweight partitioning and placement mechanism to balance the load and minimize the synchronization overheads across Islands. Overall, we show that masking the non-uniformity of inter-core communication is critical for achieving predictably high performance for latency-sensitive applications, such as transaction processing. With clusters of a handful of multicore chips with large main memories replacing high-end many-socket servers, the deployment rules of thumb identified in our analysis have a potential to significantly reduce the synchronization and communication costs of transaction processing. As workloads become more dynamic and diverse, while still running on partitioned infrastructure, the lightweight monitoring and adaptive repartitioning mechanisms proposed in this thesis will be applicable to a wide range of designs for which traditional offline schemes are impractical

Characterization and optimization of network traffic in cortical simulation

Considering the great variety of obstacles the Exascale systems have to face in the next future, a deeper attention will be given in this thesis to the interconnect and the power consumption. The data movement challenge involves the whole hierarchical organization of components in HPC systems — i.e. registers, cache, memory, disks. Running scientific applications needs to provide the most effective methods of data transport among the levels of hierarchy. On current petaflop systems, memory access at all the levels is the limiting factor in almost all applications. This drives the requirement for an interconnect achieving adequate rates of data transfer, or throughput, and reducing time delays, or latency, between the levels. Power consumption is identified as the largest hardware research challenge. The annual power cost to operate the system would be above 2.5 B$ per year for an Exascale system using current technology. The research for alternative power-efficient computing device is mandatory for the procurement of the future HPC systems. In this thesis, a preliminary approach will be offered to the critical process of co-design. Co-desing is defined as the simultaneos design of both hardware and software, to implement a desired function. This process both integrates all components of the Exascale initiative and illuminates the trade-offs that must be made within this complex undertaking