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The access to the contents of this doctoral thesis it is limited to the acceptance of the use conditions set by the following Creative Commons license: https://creativecommons.org/licenses/?lang=en David Castells Rufas Scalable Parallel Architectures on Reconfigurable Platforms Ph.D. Thesis, David Castells Rufas Department of Microelectronics and Electronic Systems Universitat Autònoma de Barcelona December 2015 Scalable Parallel Architectures on Reconfigurable Platforms Ph.D. Thesis Dissertation Author: Advisor: David Castells i Rufas Jordi Carrabina i Bordoll Universitat Autònoma de Barcelona December 2015 Bellaterra, Catalonia I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Dr. Jordi Carrabina i Bordoll This work was carried out at the Microelectronics and Electronic Systems Department of the Universitat Autònoma de Barcelona In fulfillment of the requirements for the degree of Doctorat en Informàtica © 2015 David Castells i Rufas Some Rights Reserved. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. ─ 3 ─ ─ 4 ─ Abstract The latest advances on reconfigurable systems resulted in FPGA devices with enough resources to implement multiprocessing systems with more than 100 soft-cores on a single FPGA. In this thesis I present how to implement solutions based on such systems and two scenarios where those kind of systems would be valuable: hard real-time systems and energy efficient HPC systems. FPGAs are increasingly being used in HPC computing as they can bring higher energy efficiency than other alternative architectures such as CPUs or GPGPUs. However, the programmability barrier imposed by HDL languages is a serious drawback that limits their adoption. The recent introduction of OpenCL toolchains for FPGAs is a step towards lowering the barrier, but still produces application-specific designs that cannot be reused for other general-purpose computing unless the platform is reconfigured. Building many-soft-cores solutions using simple hardware accelerators can bring performance and energy efficiency and still provide a general purpose system to be used for different applications. To make it possible the current FPGA toolchains has been complemented to add support for fast many-soft-core platform description and verification (especially at higher levels of abstraction), to provide convenient parallel programming models and efficient methods to optimize the designs. On the other hand, I show how the same methods can be applied to implement systems using a task isolation approach to meet the requirements of a hard real-time safety critical system. Finally, the application of these technologies and optimization methods are used to efficiently implement both industrial and computational research problems. ─ 5 ─ Resum Els últims avenços en els sistemes reconfigurables han fet possible que les darreres famílies de FPGAs tinguin prou recursos per permetre la implementació de sistemes multiprocessadors utilitzant més de 100 nuclis (soft-core) en una única FPGA. En aquesta tesis presento com implementar solucions basades en aquests sistemes i dos escenaris on aquests sistemes tenen interès: els sistemes de temps real dur i els sistemes d’altes prestacions eficients energèticament. Les FPGAs s’utilitzen cada vegada més en la computació d’altes prestacions ja que poden arribar a oferir més eficiència energètica que altres arquitectures com ara CPUs o GPGPUs. Tanmateix, la baixa programabilitat d’aquests sistemes, fruit de l’ús de llenguatges HDL és un inconvenient que limita la seva adopció. La introducció recent de fluxos de disseny per FPGA basats en OpenCL és un avenç per reduir la dificultat de programació, però malgrat tot, produeix arquitectures de propòsit específic que no poden reutilitzar-se per altres aplicacions a no ser que es reconfiguri la plataforma. Construint many-soft-cores que utilitzin acceleradors simples, es poden aconseguir prestacions i eficiència energètica i tot i així, encara disposar d’un sistema útil per executar altres aplicacions. Per fer-ho possible les eines de disseny actual per FPGA s’han complementat per afegir suport per construir arquitectures many-soft- core, proporcionar models de programació paral·lels i mètodes eficients per analitzar i optimitzar els dissenys. Per altra banda, es mostra com els mateixos mètodes es poden utilitzar per desenvolupar un sistema de temps real i alts nivells de seguretat mitjançant l’aïllament de tasques en els diferents nuclis del sistema. ─ 6 ─ Enthusiasm is followed by disappointment and even depression, and then by renewed enthusiasm. Murray Gell-Mann ─ 7 ─ ─ 8 ─ Acknowledgments When I started my particular journey to Ithaca I prayed that the road would be long. Unfortunately, it looks as if gods were listening me… I want express my deepest gratitude to all the people that encouraged me, that helped me, or contributed (no matter how) to make this long journey enjoyable and fun. To my daughters Anna and Carla. For being lovely…most of the time. Anyway, I love you… all the time. I am happy to finish before you get to College! I will play more with you from now on! To my ex-wife Mar. I probably devoted too much time to this, I’m sorry…and thanks for the many times you’ve expected a “thanks” coming out of my mouth that has never arrived. To my parents, my brother and his family. Thank you for being there whenever I need help. Quite often lately. To Txell. Thank you for the good times we have shared. I swear I am going to reach my toes one day. To Disposats: Àngels, Carles, Marga, Miquel, Paquito, Montse, and Rita. I miss those dinners and adventures. To my advisor Jordi Carrabina. Thanks for encouraging me to start, and not falling into despair during this last sprint. I hope you never have another Ph.D. student like me! …and this is not a self-compliment! To Eloi. Thank you for the coffees, discussions, and everything that helped me think that I was not travelling a lonely road. I hope our roads can cross again in the future. To Carme. I wish you much luck in your [shorter] journey! To Albert. For not quitting smoking for some time, and for being always ready to roll up your sleeves if needed. Lab is empty without you, man! I wish we can climb together again soon! To Jaume Joven. I had much fun working together. ─ 9 ─ To Eduard. For liking disguising! All the best with you growing family! To Joan Plana. …for our discussions about the meaning of life and for, too often, paying my lunch. Man, I will be the one inviting next time! To Josep Mesado and Martí Bonamusa. For continually asking me about some Drivers… I do not know what you are talking about! I sincerely wish that you have the success you deserve. All the best! To colleagues from UAB, especially Lluis Terés, Toni Espinosa, Juan Carlos Moure, and Emilio Luque. Thanks for sharing wisdom, thoughts and experiences. To Toni Portero and David Novo. It’s long time since we worked together now. But I’m still convinced that you are great people to have around. To David Marin. I admire your resolution and British style. To Josep Besora. Be prepared! I am going to beat you in the Tennis court someday. To my “Flama’s fathers” friends, especially Pep Claret and Xavier Montanyà. Sharing drinks and laughs with you has been one of the most effective medicines to combat disappointment and depression. To Chit Yeoh Cheng. Thanks for your help and for sharing your Chinese wisdom. To Jose Duato, Greg Yeric, Rob Aitken, and Francky Catthoor, for your comments and valuable insight. To Takehiko Iida and David Womble, for answering my mails asking for estimations of the power consumption of former #1 top500 machines. To the Catalan, Spanish, and European taxpayers. Thanks for supporting my research. To the anonymous reviewers of my papers. You were always right. To the people that smile to strangers in the street. The world is better with you in it. ─ 10 ─ Contents Abstract ......................................................................................................................................... 5 Resum ............................................................................................................................................ 6 Acknowledgments ......................................................................................................................... 9 Contents....................................................................................................................................... 11 List of Acronyms ......................................................................................................................... 15 List of Figures ............................................................................................................................. 17 List of Tables ............................................................................................................................... 23 1. Introduction ........................................................................................................................