Evaluation of TCP Based Congestion Control Algorithms Over High-Speed Networks

The Additive Increase Multiplicative Decrease (AIMD) algorithm of the Transport Control Protocol (TCP) had worked remarkably well over low speed networks and had guaranteed fairness to the users all over these years, but at present, the demands for transferring large quantities of data over very high-speed networks are increasing at a tremendous rate. Because of its AIMD algorithm to control its window growth function accompanied by a slow response function which is inadequate over high-speed links, TCP has been proven to underutilize the available network bandwidth and leave a considerable amount of unused bandwidth. To overcome this limitation of TCP, the network research community came up with a number of TCP variants: HSTCP, STCP, BIC TCP, CUBIC, HTCP, and FAST TCP. All these protocols differ in the window growth policy to utilize the available bandwidth over a high-speed link. Various tests have shown that these protocols successfully utilize the link but at the same time they are not able to guarantee fairness to the other flows in the network. In this work, we aim to explore the following research questions: ○ Explore how tuning affects the performance of TCP and over 10G networks. ○ Compare TCP variants over a high-loss back-to-back environment In future, this work can be further extended in exploring the following two questions ○ Explore Performance Metrics for fair comparison of protocols over 10G back-to-back links ○ Move towards designing a congestion control protocol for back-to-back high-speed (Gigabit) link

Clopencl (opencl para ambiente cluster)

Nos dias correntes, as pessoas estão cada vez mais familiarizadas com a necessidade de um aumento dos recursos computacionais. Com isto, torna-se evidente a junção de dispositivos, como CPUs e GPUs de fabricantes diferentes, com a finalidade de preencher o mesmo propósito. Este nível de heterogeneidade é trazida pela tecnologia OpenCL. O trabalho aqui desenvolvido abrange o High-Performance Computing e o OpenCL, com o resultado do clOpenCL. O objetivo do clOpenCL é suportar o conjunto de dispositivos OpenCL num ambiente cluster. O clOpenCL foi construído sobre duas vertentes, estando estas inteiramente ligadas ao tipo de tecnologia utilizada no processo de comunicação entre a biblioteca e o daemon. A primeira vertente da API foi construída sobre a tecnologia de comunicação socket TCP/IP e a segunda foi desenvolvida sobre o Open-MX. Ambos os modelos do clOpenCL estão ligados à tecnologia de comunicação e à forma como é suportada a comunicação ao nível de programação. No decorrer do trabalho serão apresentadas todas as caraterísticas integradas pelo clOpenCL e todos os seus recursos abrangidos. Irá também ser analisada a performance obtida para cada vertente do clOpenCL, em termos de utilização de largura de banda e com a leitura e escrita em buffers remotos. In the current days, people are increasingly acquainted with the need for an increase computing resources. It becomes evident the combination of devices such as CPUs and GPUs from different vendors, with the task of fulfill the same purpose. This level of heterogeneity, is brought by OpenCL technology. This work covers the High-Performance Computing and OpenCL, with the result of clOpenCL. The main goal of clOpenCL is to support a set of OpenCL devices in a cluster environment. The clOpenCL was built in two branches, fully connected with the type of technology used in the comunication process, between the library and the daemon. The first version of the API was built on socket TCP/IP communication technology, and the second one was developed on the Open-MX tecnology. Both clOpenCL models are connected to the communication technology and the way that communication is supported at programming level. Throughout this work, we will present all the clOpenCL integrated features and all its covered resources. We will also analyze the performance obtained for each side of clOpenCL in terms of bandwidth usage, through the reading and writing of remote buffers