33 lines
1.8 KiB
Plaintext
33 lines
1.8 KiB
Plaintext
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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 openmamba requires some compromises.
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Firstly, 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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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. Second, building from the same source package must
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result in identical binaries for any computer of a particular
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architecture. This is because the binaries installed on a user's
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computer are built on a computer in the openmamba Extras build system,
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which will have hardware different from the end user's hardware, and
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quite possibly different from other available hardware in the build
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system.
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For i386 systems, 3 ATLAS subpackages are built for SSE1, SSE2, and SSE3 ix86
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extensions, using architectural defaults obtained from PIII, Pentium 4 with
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SSE2 extension and PENTIUM 4 with SSE3 extensions respectively.
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This package is designed to build RPMs that are identical regardless
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of where they are compiled and that provide reasonable performance on
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a wide range of hardware. 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 libatlas-@VER_REL@.src.rpm
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This will cause the ATLAS build to use the achitectural default most
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appropriate for the system on which the package is to be built.
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