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List: kde-kimageshop
Subject: MPI issues
From: "Bavo De Ridder" <bavodr () poboxes ! com>
Date: 1999-07-25 19:14:32
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Hello,
One more remark: instead of including MPI, we would better include some kind
of numerical library with optimised implementations of some algorithms.
These libraries can avoid or minimize among others cache trashing. They also
give high performance implementations of BLAS level 1, 2 and 3. Most
inexperienced programmers often reach only 1/3 of ½ of the maximum available
computer power because of bad algorithm implementations. I think of
libraries using MMX instead of the plain old x86 instructions. Using MMX (or
its successor), WILL give you a big performance gain !
Multithreading will only give good performance in 10% of the cases. When
applying a filter, communication overhead and synchronization will probably
degrade any multithreading performance unless very experienced programmers
wrote the filters AND if the images are large (> 10^6 pixels), large images
also means large transports of data, so communication start-up time will be
negligible.
Bavo De Ridder
bavodr@poboxes.com
+32 (476) 24 58 36
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face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'>One more remark: instead of including MPI, we would better include some
kind of numerical library with optimised implementations of some algorithms. These
libraries can avoid or minimize among others cache trashing. They also give
high performance implementations of BLAS level 1, 2 and 3. Most inexperienced
programmers often reach only 1/3 of ½ of the maximum available computer power
because of bad algorithm implementations. I think of libraries using MMX
instead of the plain old x86 instructions. Using MMX (or its successor), WILL
give you a big performance gain !<o:p></o:p></span></font></span></p>
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face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'>Multithreading will only give good performance in 10% of the cases. When
applying a filter, communication overhead and synchronization will probably
degrade any multithreading performance unless very experienced programmers
wrote the filters AND if the images are large (> 10^6 pixels), large images
also means large transports of data, so communication start-up time will be \
negligible.<o:p></o:p></span></font></span></p>
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<p class=MsoAutoSig><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'>Bavo De Ridder</span></font><font
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<p class=MsoAutoSig><font size=3 color=black face="Times New Roman"><span
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<p class=MsoAutoSig><font size=3 color=black face="Times New Roman"><span
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