1 2 Mesa 3.0 MITS Information 3 4 5 This software is distributed under the terms of the GNU Library 6 General Public License, see the LICENSE file for details. 7 8 9 This document is a preliminary introduction to help you get 10 started. For more detaile information consult the web page. 11 12 http://10-dencies.zkm.de/~mesa/ 13 14 15 16 Version 0.1 (Yes it's very alpha code so be warned!) 17 Contributors: 18 Emil Briggs (briggs (a] bucky.physics.ncsu.edu) 19 David Bucciarelli (tech.hmw (a] plus.it) 20 Andreas Schiffler (schiffler (a] zkm.de) 21 22 23 24 1. Requirements: 25 Mesa 3.0. 26 An SMP capable machine running Linux 2.x 27 libpthread installed on your machine. 28 29 30 2. What does MITS stand for? 31 MITS stands for Mesa Internal Threading System. By adding 32 internal threading to Mesa it should be possible to improve 33 performance of OpenGL applications on SMP machines. 34 35 36 3. Do applications have to be recoded to take advantage of MITS? 37 No. The threading is internal to Mesa and transparent to 38 applications. 39 40 41 4. Will all applications benefit from the current implementation of MITS? 42 No. This implementation splits the processing of the vertex buffer 43 over two threads. There is a certain amount of overhead involved 44 with the thread synchronization and if there is not enough work 45 to be done the extra overhead outweighs any speedup from using 46 dual processors. You will not for example see any speedup when 47 running Quake because it uses GL_POLYGON and there is only one 48 polygon for each vertex buffer processed. Test results on a 49 dual 200 Mhz. Pentium Pro system show that one needs around 50 100-200 vertices in the vertex buffer before any there is any 51 appreciable benefit from the threading. 52 53 54 5. Are there any parameters that I can tune to try to improve performance. 55 Yes. You can try to vary the size of the vertex buffer which is 56 define in VB_MAX located in the file src/vb.h from your top level 57 Mesa distribution. The number needs to be a multiple of 12 and 58 the optimum value will probably depend on the capabilities of 59 your machine and the particular application you are running. 60 61 62 6. Are there any ways I can modify the application to improve its 63 performance with the MITS? 64 Yes. Try to use as many vertices between each Begin/End pair 65 as possbile. This will reduce the thread synchronization 66 overhead. 67 68 69 7. What sort of speedups can I expect? 70 On some benchmarks performance gains of up to 30% have been 71 observerd. Others may see no gain at all and in a few rare 72 cases even some degradation. 73 74 75 8. What still needs to be done? 76 Lots of testing and benchmarking. 77 A portable implementation that works within the Mesa thread API. 78 Threading of additional areas of Mesa to improve performance 79 even more. 80 81 82 83 Installation: 84 85 1. This assumes that you already have a working Mesa 3.0 installation 86 from source. 87 2. Place the tarball MITS.tar.gz in your top level Mesa directory. 88 3. Unzip it and untar it. It will replace the following files in 89 your Mesa source tree so back them up if you want to save them. 90 91 92 README.MITS 93 Make-config 94 Makefile 95 mklib.glide 96 src/vbxform.c 97 src/vb.h 98 99 4. Rebuild Mesa using the command 100 101 make linux-386-glide-mits 102 103
