Mark Joselli, Marcelo Zamith, Esteban Clua, Regina Leal-Toledo, Anselmo Montenegro, Luis Valente, Bruno Feijo and Paulo Pagliosa

Nowadays, multithread hardware architectures like multi-core CPUs and GPUs found on PCs and game consoles (as Microsoft Xbox 360 and Sony Playstation 3) are a trend. Hence, real-time simulation and visualization systems, such as scientific visualization, games and virtual reality environments, will not get the best performance on such architectures running sequentially in a single-thread loop. For this reason, multithread real-time loop models that take advantage of such architectures are gaining importance. This paper presents a survey on loop models for games and real-time systems. Also it discusses the usage of simple loops with single-thread architecture and multithread loop architectures in scientific simulations and visualization systems. Furthermore, this paper presents a new architecture for real-time loops that can detect and analyze the user hardware in order to adapt itself to a specific loop model, achieving the best performance for a specific hardware and application.

Parallel computing, task distribution, GPGPU, real-time loop models, real-time systems, multithread architectures for real-time systems, real-time applications.

[1] AMD. 2007. Amd stream computing. Available at: http://ati.amd.com/ technology/streamcomputing/firestream-sdkwhitepaper.pdf. 20/02/2008.

[2] J. BOLZ, I. FARMER, E. GRISPUN & P. SCHRDER. 2003. Sparse matrix solvers on the gpu: conjugate gradients and multigrid. ACM Transactions on Graphics, 22(3): 917-924.

[3] D. SANCHEZ & C. DALMAU. 2003. Core Techniques and Algorithms in Game Programming. New Riders Publishing.

[4] P. DICKINSON. 2001. Instant replay: Building a game engine with reproducible behavior. Available at: http://www.gamasutra.com/features/ 20010713/dickinson 01.htm/.

[5] H. GABB & A. LAKE. 2005. Threading 3d game engine basics. Available at: http://www.gamasutra.com/features/20051117/gabb 01.shtml/.

[6] SIMON GREEN. 2007. Gpgpu physics. Siggraph07 GPGPU Tutorial.

[7] KHRONOS GROUP. 2009. Opencl - the open standard for parallel programming of heterogeneous systems. Available at: http://www.khronos.org/opencl/.

[8] ROBERTO IERUSALIMSCHY, LUIZ HENRIQUE DE FIGUEIREDO & WALDEMAR CELES. 2006. Lua 5.1 Reference Manual. Lua.org.

[9] M. JOSELLI, M. ZAMITH, E. CLUA, P. PAGLIOSA, A. CONCI, A. MONTENEGRO & L. VALENTE. 2008. An adaptative game loop architecture with automatic distribution of tasks between cpu and gpu. Proceedings of the VII Brazilian Symposium on Computer Games and Digital Entertainment, pages 115-120.

[10] M. JOSELLI, M. ZAMITH, L. VALENTE, E.W.G. CLUA, A. MONTENEGRO, A. CONCI, B. FEIJO, M. DORNELLAS, R. LEAL & C. POZZER. Ž 2008. Automatic dynamic task distribution between cpu and gpu for realtime systems. IEEE Proceedings of the 11 th International Conference on Computational Science and Engineering, pages 48-55.

[11] MARK JOSELLI, ESTEBAN CLUA, ANSELMO MONTENEGRO, AURA CONCI & PAULO PAGLIOSA. 2008. A new physics engine with automatic process distribution between cpu-gpu. Sandbox 08: Proceedings of the 2008 ACM SIGGRAPH symposium on Video games, pages 149-156.

[12] A. KERR, D. CAMPBELL & M. RICHARDS. 2008. Gpu vsipl: Highperformance vsipl implementation for gpus. In High Performance Embedded Computing.

[13] J. KIEL & S. DIETRICH. 2006. Gpu performance tuning with nvidia performance tools. Game Developers Conference.

[14] J. KRUEGER. 2008. A gpu framework for interactive simulation and rendering of fluid effects. IT - Information Technology, 4: (accepted).

[15] LUA. 2009. The programming language lua. Avalible at: http://www.lua.org, 2009. 13/01/2009.

[16] MICROSOFT. 2006. Xna 1.0 documentation. Available at: help:// MS.VSExpressCC.v80/MS.VSIPCC.v80/MS.XNAFX.1033/XNA/ AppModel GameLoop.htm.

[17] V. MNKKNEN. 2006. Multithreaded game engine architectures. Available at: http://www.gamasutra.com/features/20060906/monkkonen 01.shtml.

[18] nVidia. 2007. Nvidia cuda compute unified device architecture documentation version 1.1. Avalible at: http://developer.nvidia.com/object/cuda.html, 2007. 20/12/2007.

[19] nVidia. 2009. Physx. Avalible at: http://www.nvidia.com/object/nvidia physx.html, 2009. 20/02/2009.

[20] LARS NYLAND, MARK HARRIS & JAN PRINS. 2007. Fast n-body simulation with cuda. GPU Gems 3 Chapter 31, pages 677-695.

[21] E. PASSOS, MARK JOSELLI, M. ZAMITH, J. ROCHA, A. MONTENEGRO, E. CLUA, A. CONCI & B. FEIJO. 2008. Supermassive crowd Ž simulation on gpu based on emergent behavior. In Proceedings of the VII Brazilian Symposium on Computer Games and Digital Entertainment, pages 81-86.

[22] CRAIG W. REYNOLDS. 1987. Flocks, herds and schools: A distributed behavioral model. In SIGGRAPH '87: Proceedings of the 14 th annual conference on Computer graphics and interactive techniques, pages 25- 34, New York, NY, USA, ACM.

[23] ABDENNOUR EL RHALIBI, STEVE COSTA & DAVID ENGLAND. 2006. Game engineering for a multiprocessor architecture. In DIGRA Conf.

[24] T. RUDOMN, E. MILLN & B. HERNNDEZ. 2005. Fragment shaders for agent animation using finite state machines. Simulation Modelling Practice and Theory, 13(8): 741-751.

[25] LARRY SEILER, DOUG CARMEAN, ERIC SPRANGLE, TOM FORSYTH, MICHAEL ABRASH, PRADEEP DUBEY, STEPHEN JUNKINS, ADAM LAKE, JEREMY SUGERMAN, ROBERT CAVIN, ROGER ESPASA, ED GROCHOWSKI, TONI JUAN & PAT HANRAHAN. 2008. Larrabee: A many-core x86 architecture for visual computing. ACM Transactions on Graphics, 27(3).

[26] IVAN S. UFIMTSEV & TODD J. MARTNEZ. 2008. Quantum chemistry on graphical processing units. 1. strategies for two-electron integral evaluation. Journal Chemistry Theory Computation, 4 (2): 222-231.

[27] LUIS VALENTE, AURA CONCI & BRUNO FEIJO. 2005. Real time Ž game loop models for single-player computer games. In Proceedings of the IV Brazilian Symposium on Computer Games and Digital Entertainment, pages 89-99.

[28] J. WATTE. 2005. Canonical game loop. Available at: www.mindcontrol.org/hplus/graphics/game loop.html/.

[29] M. ZAMITH, E. CLUA, P. PAGLIOSA, A. CONCI, A. MONTENEGRO & L. VALENTE. 2007. The gpu used as a math co-processor in real time applications. Proceedings of the VI Brazilian Symposium on Computer Games and Digital Entertainment, pages 37-43.

[30] MARCELO P.M. ZAMITH, ESTEBAN W.G. CLUA, AURA CONCI, ANSELMO MONTENEGRO, REGINA C.P. LEAL-TOLEDO, PAULO A. PAGLIOSA, LUIS VALENTE & BRUNO FEIJO. 2008. A game loop architecture Ž for the gpu used as a math coprocessor in real-time applications. Comput. Entertain., 6(3): 1-19.