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Notes on the packaged version of ATLAS
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by Quentin Spencer
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updated: October 4, 2005
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updated by Deji Akingunola
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October 15, 2008
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updated by Deji Akingunola
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June 15, 2011
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updated by Frantisek Kluknavsky
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Nov 20, 2012
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Because ATLAS relies on compile-time optimizations to obtain improved
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performance over BLAS and LAPACK, the resulting binaries are closely
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tied to the hardware on which they are compiled, and can likely result
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in very poor performance on other hardware. For this reason,
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including a package like ATLAS in Fedora requires some compromises.
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Optimizing ATLAS for the most modern hardware can result in
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significant performance penalties for users using the same package on
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older hardware. A binary ATLAS package must perform reasonably well on the
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entire range of hardware on which it could potentially be installed.
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The result is a set of libraries that will not
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necessarily achieve optimal performance on any given hardware but
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should still offer significant performance gains over the reference
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BLAS and LAPACK libraries on most hardware.
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In addition to the base 32bit build, subpackages are built for SSE, SSE2,
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and SSE3 ix86 extensions.
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On 64bit x86 systems the default atlas package was built with SSE3
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optimization.
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This packaging allows multiple installation of different atlas sub-packages
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at the same time. The alternatives system (read 'man alternatives' for usage)
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is used in the -devel subpackages to select the appropriate location for the
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architectural dependent header files.
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For users who want optimal performance on
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particular hardware, custom RPMs can be built from the source package
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by setting the RPM macro "enable_native_atlas" to a value of 1. This
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can be done from the command line as in the following example:
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rpmbuild -D "enable_native_atlas 1" --rebuild atlas-3.8.3-1.src.rpm
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