103 lines
3.2 KiB
Plaintext
103 lines
3.2 KiB
Plaintext
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Mesa 3.0 MITS Information
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This software is distributed under the terms of the GNU Library
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General Public License, see the LICENSE file for details.
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This document is a preliminary introduction to help you get
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started. For more detaile information consult the web page.
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http://10-dencies.zkm.de/~mesa/
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Version 0.1 (Yes it's very alpha code so be warned!)
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Contributors:
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Emil Briggs (briggs@bucky.physics.ncsu.edu)
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David Bucciarelli (tech.hmw@plus.it)
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Andreas Schiffler (schiffler@zkm.de)
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1. Requirements:
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Mesa 3.0.
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An SMP capable machine running Linux 2.x
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libpthread installed on your machine.
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2. What does MITS stand for?
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MITS stands for Mesa Internal Threading System. By adding
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internal threading to Mesa it should be possible to improve
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performance of OpenGL applications on SMP machines.
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3. Do applications have to be recoded to take advantage of MITS?
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No. The threading is internal to Mesa and transparent to
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applications.
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4. Will all applications benefit from the current implementation of MITS?
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No. This implementation splits the processing of the vertex buffer
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over two threads. There is a certain amount of overhead involved
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with the thread synchronization and if there is not enough work
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to be done the extra overhead outweighs any speedup from using
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dual processors. You will not for example see any speedup when
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running Quake because it uses GL_POLYGON and there is only one
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polygon for each vertex buffer processed. Test results on a
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dual 200 Mhz. Pentium Pro system show that one needs around
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100-200 vertices in the vertex buffer before any there is any
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appreciable benefit from the threading.
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5. Are there any parameters that I can tune to try to improve performance.
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Yes. You can try to vary the size of the vertex buffer which is
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define in VB_MAX located in the file src/vb.h from your top level
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Mesa distribution. The number needs to be a multiple of 12 and
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the optimum value will probably depend on the capabilities of
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your machine and the particular application you are running.
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6. Are there any ways I can modify the application to improve its
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performance with the MITS?
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Yes. Try to use as many vertices between each Begin/End pair
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as possbile. This will reduce the thread synchronization
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overhead.
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7. What sort of speedups can I expect?
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On some benchmarks performance gains of up to 30% have been
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observerd. Others may see no gain at all and in a few rare
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cases even some degradation.
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8. What still needs to be done?
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Lots of testing and benchmarking.
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A portable implementation that works within the Mesa thread API.
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Threading of additional areas of Mesa to improve performance
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even more.
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Installation:
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1. This assumes that you already have a working Mesa 3.0 installation
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from source.
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2. Place the tarball MITS.tar.gz in your top level Mesa directory.
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3. Unzip it and untar it. It will replace the following files in
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your Mesa source tree so back them up if you want to save them.
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README.MITS
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Make-config
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Makefile
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mklib.glide
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src/vbxform.c
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src/vb.h
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4. Rebuild Mesa using the command
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make linux-386-glide-mits
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