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A Support of GVFS Caching
Holý, Ondřej ; Zelený, Jan (referee) ; Smrčka, Aleš (advisor)
The master's thesis deals with a support of caching in GVfs (Gnome Virtual filesystem). Basics of caches, cache invalidation, and cache replacement algorithms are described. Description of GIO filesystem abstraction and communication of modules within GVfs is provided next. The disadvantages of individual GVfs modules and, if present, their internal caches are discussed. The thesis proposes three types of cache. The first type of cache is for storing file metadata, the second one for directory listings, and the latter for file content. These caches have been implemented in a prototype and verified with respect to the functionality and performance. The main benefits of the proposed solution are faster work with virtual filesystems and provided missing functionality of lower-level virtual filesystem to GIO abstraction (namely, for instance seek operation).
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Simulation scenarios in NS2 demonstrating knowledge obtained in the MPKT course
Mašek, Jan ; Mlýnek, Petr (referee) ; Jeřábek, Jan (advisor)
The aim of the bachelor´s thesis is to develop simulation tasks for modeling of data networks. The tasks will be used in the course Modern communication technique (MKPT). The networks are simulated in the environment of Network Simulator 2 (NS2). A brief description of program environment NS2, as well as basics of Tcl language is mentioned in the introduction. Described is the possibility of simulation HTTP protocol in NS2 using OTcl PagePool classes. Totally six proposed tasks form the core of the thesis. The first task uses PagePool/Math and displays the simplest communication between client, server and cache. Next task uses PagePool/CompMath and it shows the communication between client, cache, Web server, FTP server and FTP client. The task, that uses PagePool/WebTraf class, simulates communication between two clients and three servers. The last three tasks are of different topologies and course of communication using PagePool/ProxyTrace. The exercises of this class are the most complicated and their input files allow defining whole communication. The outputs of exercises are given in graphs, log files of HTTP communication and the last task contains detailed instructions.
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AES Tolerance to Timing Analysis
Ondruš, Juraj ; Matyáš, Václav (referee) ; Cvrček, Daniel (advisor)
This thesis deals with timing analysis of the AES (Advanced Encryption Standard). The design of {\em Rijndael\/}, which is the AES algorithm, is described here. For the side channel attacks is necessary to know the principles of the cache memory in CPU and its architecture. In this thesis are involved major security problems of AES which can be used for successful attacks. Several different implementations of AES are discussed too. Several types of timing attaks are also described. According to the experimentations these attacks should be efficient to the most presently used AES implementations. Finally, the results of this work are described, possible countermeasures against this attack and motions for the next research.
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Web Administration Interface for Caché
Valena, Pavel ; Kolář, Dušan (referee) ; Burget, Radek (advisor)
The goal of this bachelor’s thesis is to create web administration interface for Caché, where database data is clearly and logically displayed. Enabling user to edit database data, manage users and databases. The thesis describes the design and implementation process of this web interface.
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CACHE Memory Design for Network Applications
Soľanka, Lukáš ; Martínek, Tomáš (referee) ; Kořenek, Jan (advisor)
This thesis deals with design and implementation of generic cache memory for a wide range of network applications. Firstly, aspects with influence on performance are discussed. Then architecture is proposed and implemented with respect to the given technology. The main selectable parameters of the design are: data path width, line size, associativity, number of lines and replacement policy. Cache is also pipelined and therefore is able to process one request for reading or writing every clock cycle. The resulting component has been thoroughly simulated to verify its functionality and finally, its operation has also been tested in hardware on the Combo6X board.
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Data standard of the Ministry of Health of the Czech Republic
Holub, Martin ; Roleček, Jiří (referee) ; Fedra, Petr (advisor)
Diploma thesis "Data standard of the Ministry of Health" deals with the structure of data standard including XML language. Further the thesis is focusing on hospital information system CLINICOM with the inclusion of the access to data records from its database Caché company InterSystems. The concept of web application is also one part of the thesis which enables to find out records with selective diagnosis from Caché database and their depictions in data standard of the Ministry of Health of the Czech Republic.
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Optimization of network flow monitoring
Žádník, Martin ; Lhotka,, Ladislav (referee) ; Matoušek, Radomil (referee) ; Sekanina, Lukáš (advisor)
The thesis deals with optimization of network flow monitoring. Flow-based network traffic processing, that is, processing packets based on some state information associated to the flows which the packets belong to, is a key enabler for a variety of network services and applications. The number of simultaneous flows increases with the growing number of new services and applications. It has become a challenge to keep a state per each flow in a network device processing high speed traffic. A flow table, a structure with flow states, must be stored in a memory hierarchy. The memory closest to the processing is known as a flow cache. Flow cache management plays an important role in terms of its effective utilization, which affects the performance of the whole system. This thesis focuses on an automated design of cache replacement policy optimized to a deployment on particular networks. A genetic algorithm is proposed to automate this process. The genetic algorithm generates and evaluates evolved replacement policies by a simulation on obtained traffic traces. The proposed algorithm is evaluated by designing replacement policies for two variations of the cache management problem. The first variation is an evolution of the replacement policy with an overall low number of state evictions from the flow cache. The second variation represents an evolution of the replacement policy with a low number of evictions belonging to large flows only. Optimized replacement policies for both variations are found while experimenting with various encoding of the replacement policy and genetic operators. The newly evolved replacement policies achieve better results than other tested policies. The evolved replacement policy lowers the overall amount of evictions by ten percent in comparison with the best compared policy. The evolved replacement policy focusing on large flows lowers the amount of their evictions two times. Moreover, no eviction occurs for most of the large flows (over 90%). The evolved replacement policy offers better resilience against flooding the flow cache with large amount of short flows which are typical side effects of scanning or distributed denial of service activities. An extension of the replacement policy is also proposed. The extension complements the replacement policy with an additional information extracted from packet headers. The results show further decrease in the number of evictions when the extension is used.
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Assisted Code Vectorization and Parallelization Using the OpenMP 4.0 Standard
Slouka, Lukáš ; Nikl, Vojtěch (referee) ; Jaroš, Jiří (advisor)
The subject of the bachelor's thesis is code optimization using the OpenMP 4.0 standard which provides tools for assisted parallelization and vectorization. In addition to the descrip tion of the OpenMP 4.0 standard, the thesis as well contains an insight into architectures of modern computers, specifically the system of cache memories and SSE/AVX modules that play a major role in the optimization field. The thesis demonstrates advantages of optimized code compared to unoptimized version on a set of benchmarks which are aimed at various aspects of optimization.
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