Reducing Response Time with Preheated Caches

CPU performance is increasingly limited by thermal dissipation, and soon aggressive power management will be beneficial for performance. Especially, temporarily idle parts of the chip (including the caches) should be power-gated in order to reduce leakage power. Current CPUs already lose their cache state whenever the CPU is idle for extended periods of time, which causes a performance loss when execution is resumed, due to the high number of cache misses when the working set is fetched from external memory. In a server system, the first network request during this period suffers from increased response time. We present a technique to reduce this overhead by preheating the caches in advance before the network request arrives at the server: Our design predicts the working set of the server application by analyzing the cache contents after similar requests have been processed. As soon as an estimate of the working set is available, a predictable network architecture starts to announce future incoming network packets to the server, which then loads the predicted working set into the cache. Our experiments show that, if this preheating step is complete when the network packet arrives, the response time overhead is reduced by an average of 80%

Cloud-efficient modelling and simulation of magnetic nano materials

Scientific simulations are rarely attempted in a cloud due to the substantial performance costs of virtualization. Considerable communication overheads, intolerable latencies, and inefficient hardware emulation are the main reasons why this emerging technology has not been fully exploited. On the other hand, the progress of computing infrastructure nowadays is strongly dependent on perspective storage medium development, where efficient micromagnetic simulations play a vital role in future memory design. This thesis addresses both these topics by merging micromagnetic simulations with the latest OpenStack cloud implementation while providing a time and costeffective alternative to expensive computing centers. However, many challenges have to be addressed before a high-performance cloud platform emerges as a solution for problems in micromagnetic research communities. First, the best solver candidate has to be selected and further improved, particularly in the parallelization and process communication domain. Second, a 3-level cloud communication hierarchy needs to be recognized and each segment adequately addressed. The required steps include breaking the VMisolation for the host’s shared memory activation, cloud network-stack tuning, optimization, and efficient communication hardware integration. The project work concludes with practical measurements and confirmation of successfully implemented simulation into an open-source cloud environment. It is achieved that the renewed Magpar solver runs for the first time in the OpenStack cloud by using ivshmem for shared memory communication. Also, extensive measurements proved the effectiveness of our solutions, yielding from sixty percent to over ten times better results than those achieved in the standard cloud.Aufgrund der erheblichen Leistungskosten der Virtualisierung werden wissenschaftliche Simulationen in einer Cloud selten versucht. Beträchtlicher Kommunikationsaufwand, erhebliche Latenzen und ineffiziente Hardwareemulation sind die Hauptgründe, warum diese aufkommende Technologie nicht vollständig genutzt wurde. Andererseits hängt der Fortschritt der Computertechnologie heutzutage stark von der Entwicklung perspektivischer Speichermedien ab, bei denen effiziente mikromagnetische Simulationen eine wichtige Rolle für die zukünftige Speichertechnologie spielen. Diese Arbeit befasst sich mit diesen beiden Themen, indem mikromagnetische Simulationen mit der neuesten OpenStack Cloud-Implementierung zusammengeführt werden, um eine zeit- und kostengünstige Alternative zu teuren Rechenzentren bereitzustellen. Viele Herausforderungen müssen jedoch angegangen werden, bevor eine leistungsstarke Cloud-Plattform als Lösung für Probleme in mikromagnetischen Forschungsgemeinschaften entsteht. Zunächst muss der beste Kandidat für die Lösung ausgewählt und weiter verbessert werden, insbesondere im Bereich der Parallelisierung und Prozesskommunikation. Zweitens muss eine 3-stufige CloudKommunikationshierarchie erkannt und jedes Segment angemessen adressiert werden. Die erforderlichen Schritte umfassen das Aufheben der VM-Isolation, um den gemeinsam genutzten Speicher zwischen Cloud-Instanzen zu aktivieren, die Optimierung des Cloud-Netzwerkstapels und die effiziente Integration von Kommunikationshardware. Die praktische Arbeit endet mit Messungen und der Bestätigung einer erfolgreich implementierten Simulation in einer Open-Source Cloud-Umgebung. Als Ergebnis haben wir erreicht, dass der neu erstellte Magpar-Solver zum ersten Mal in der OpenStack Cloud ausgeführt wird, indem ivshmem für die Shared-Memory Kommunikation verwendet wird. Umfangreiche Messungen haben auch die Wirksamkeit unserer Lösungen bewiesen und von sechzig Prozent bis zu zehnmal besseren Ergebnissen als in der Standard Cloud geführt

Light-weight Routing Protocol in IoT-based Inter-Device Telecommunication Wireless Environment

The primary task for IoT-based hyper-connectivity communications lies in the development of direct communications technique among IoT devices in RPL (Routing Protocol for Low-Power and Lossy Networks) environment without the aid from infras such as access points, base stations etc. In a low-power and lossy wireless network, IoT devices and routers cannot keep the original path toward the destination since they have the limited memory, except for a limited number of the default router information.. Different from the previous light-weight routing protocols focusing on the reduction of the control messages, the proposed scheme provides the light-weight IPv6 address auto-configuration, IPv6 neighbor discovery and routing protocol in a IoT capable infra-less wireless networks with the bloom filer and enhanced rank concepts. And for the first time we evaluate our proposed scheme based on the modeling of various probability distributions in the IoT environments with the lossy wireless link. Specifically, the proposed enhanced RPL based light-weight routing protocol improves the robustness with the multi-paths locally established based on the enhanced rank concepts even though lossy wireless links are existed. We showed the improvements of the proposed scheme up to 40% than the RPL based protocol

LYNXTUN.

Lynxtun is a VPN solution that allows the creation of a secure tunnel between two hosts over an insecure network. The Lynxtun Protocol transmits fully encrypted datagrams with a fixed size and at a fixed interval using UDP/IP. Our custom authenticated encryption scheme uses the AES-256 block cipher and modified version of GCM mode in order to decrypt and authenticate datagrams efficiently. It ensures traffic flow confidentiality by maintaining a constant bitrate that does not depend on underlying communication. In this sense, it provides unobservable communication. This constitutes a difficult engineering problem. The protocol design allows implementations to fulfill this requirement. We analyze factors that influence realtime behavior and propose solutions to mitigate this. We developed a full implementation for the GNU/Linux operating system in the C programming language. Our implementation succeeds in performing dispatch operations at the correct time, with a tolerance on the order of microseconds, as we have verified empirically.M.S. - Master of Scienc

Performance measurement and analysis of PC based cluster server using SET of Architecture and modeling a scalable High performance cluster

Not availabl

Sensitivity Analysis of the Thunder Combat Simulation Model to Command and Control Inputs Accomplished in a Parallel Environment

This research had two objectives. The first was to develop a methodology to demonstrate the parallel processing capability provided by Air Force\u27s Aeronautical System\u27s Command (ASC) Major Shared Resource Center (MSRC) and apply that methodology to the SIMAF Proof of Concept project. Secondly, AFSAA/SAAB requested a sensitivity analysis of THUNDER to the modeled command and control (C2) inputs. The power of parallelization can not be overemphasized. The data collection phase of this thesis was accomplished at the MSRC using a script developed to automate the processing of an experimental design, providing the analyst with a launch and leave capability. On average it took 45 minutes to process a single replication of THUNDER. For this thesis we made 1,560 runs in slightly less than 3 days. To accomplish the same number of runs on a single CPU machine would have taken slightly more than 3 months. For our sensitivity analysis we used a Plackett and Burman Resolution III screening design to identify which of 11 input variables had a statistical impact upon THUNDER. The decision to investigate only the significant variables reduced the number of input variables from 11 to 5. This reduced the number of design points necessary to obtain the same Resolution V information from 128 to 16 and eliminated the need for 3,360 THUNDER runs. A significant savings! Using response surface methodology (RSM) techniques, we were then able to generate a response surface depicting the relationships between the input parameters and the output measures

Real-time integration of IEQ with BIM - user centered approach

Altering indoor environment to increase occupants comfort may increase their productivity and reduce waste in time, energy and resources. This work attempts to understand occupants behavior and comfort to build a platform that visualizes user-centered parameters related to indoor environment in real-time using IoT. User-centered prototype platform was designed, built and tested. Gamification concepts was applied to increase participation. The results were visualized and spatially mapped to the 3D model. This platform may help users build better perception about their indoor environment,i.e in offices, schools, hotels and hospitals, using interactive content and games. Also, it may help decision makers to take faster and better decisions, relying on the abundance of user-centered data, which may help in quality improvement. A test with around 20 users was made to assess indoor and learning environments. Many have found the system useful and easy to use on their mobile devices. Users shared valuable feedbacks and ideas for further developments. The first experiment gave important insights for possible future tests

HotFuzz: Discovering Algorithmic Denial-of-Service Vulnerabilities Through Guided Micro-Fuzzing

Contemporary fuzz testing techniques focus on identifying memory corruption vulnerabilities that allow adversaries to achieve either remote code execution or information disclosure. Meanwhile, Algorithmic Complexity (AC)vulnerabilities, which are a common attack vector for denial-of-service attacks, remain an understudied threat. In this paper, we present HotFuzz, a framework for automatically discovering AC vulnerabilities in Java libraries. HotFuzz uses micro-fuzzing, a genetic algorithm that evolves arbitrary Java objects in order to trigger the worst-case performance for a method under test. We define Small Recursive Instantiation (SRI) as a technique to derive seed inputs represented as Java objects to micro-fuzzing. After micro-fuzzing, HotFuzz synthesizes test cases that triggered AC vulnerabilities into Java programs and monitors their execution in order to reproduce vulnerabilities outside the fuzzing framework. HotFuzz outputs those programs that exhibit high CPU utilization as witnesses for AC vulnerabilities in a Java library. We evaluate HotFuzz over the Java Runtime Environment (JRE), the 100 most popular Java libraries on Maven, and challenges contained in the DARPA Space and Time Analysis for Cybersecurity (STAC) program. We evaluate SRI's effectiveness by comparing the performance of micro-fuzzing with SRI, measured by the number of AC vulnerabilities detected, to simply using empty values as seed inputs. In this evaluation, we verified known AC vulnerabilities, discovered previously unknown AC vulnerabilities that we responsibly reported to vendors, and received confirmation from both IBM and Oracle. Our results demonstrate that micro-fuzzing finds AC vulnerabilities in real-world software, and that micro-fuzzing with SRI-derived seed inputs outperforms using empty values.Comment: Network and Distributed Systems Security (NDSS) Symposium, San Diego, CA, USA, February 202