101 lines
4.9 KiB
Plaintext
101 lines
4.9 KiB
Plaintext
ATLAS (Automatically Tuned Linear Algebra Software) is an ongoing
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research effort focusing on applying empirical techniques in order to
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provide portable performance. At present, it provides C and Fortran77
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interfaces to a portably efficient BLAS implementation, as well as a few
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routines from LAPACK.
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IMPORTANT NOTES:
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1) Please note that the present SlackBuild for ATLAS does by no means
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try to take into account all configuration/build issues of ATLAS.
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Nevertheless, the relevant patches mentioned in the ATLAS Errata
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are applied.
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2) The script takes advantage of the fact that the compilers shipped with
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Slackware should be OK. It also assumes that you are installing on an x86
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or x86_64 platform. If you decide to use other compilers or install on
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another platform, you are unfortunately on your own and welcome to suggest
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improvements or patches to this SlackBuild. Moreover, there is no "post
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install" tuning performed.
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3) ATLAS does not conflict with the reference netlib BLAS (see also note 6).
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Nevertheless, if ATLAS got installed successfully you should consider removing
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netlib BLAS and (re)compiling every BLAS dependent package (starting with
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LAPACK) against ATLAS. Otherwise you may not have much gain from installing
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ATLAS and may even get into problems (see next note).
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4) There is a strong interaction between ATLAS and LAPACK. If you want to install
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ATLAS just for testing and avoid problems with LAPACK you are urged to make
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use of the SYS_DESTDIR variable as explained later. Otherwise consider the
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following:
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a) It is not recommended to install LAPACK just along ATLAS, i.e. without building
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it against ATLAS. Moreover, if LAPACK is already installed you have to first
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remove it and later on build it against ATLAS.
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b) If ATLAS+LAPACK doesn't work for you, just stick with (netlib) BLAS+LAPACK.
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Netlib BLAS is also available as a SlackBuild.
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c) If ATLAS+LAPACK is installed you have to recompile and reinstall LAPACK after
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each ATLAS upgrade.
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5) ATLAS conflicts with cblas.
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6) You have to have netlib BLAS installed before you install ATLAS. As stated
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above, you should consider removing it from your system afterwards.
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INSTALLATION DETAILS:
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1) Make sure CPU throttling is off before starting the install. This is
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important, since ATLAS has to tune itself.
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2) For the same reason, keep the load on the system as low as possible
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while building ATLAS.
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3) There are a few extra variables which you may want or need
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to give appropriate values when calling the atlas.SlackBuild:
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MAX_MALLOC, REF_BLAS, USE_ARCH_DEFAULTS, SYS_DESTDIR and
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DEFAULT_DOCS.
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MAX_MALLOC is for adjusting the maximal size IN BYTES(!) that ATLAS
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is allowed to allocate. According to the ATLAS errata, a too small
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value may strongly reduce threaded performance. The default value
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within this SlackBuild corresponds to 256MB. (The default value in
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the ATLAS source corresponds to 64MB.)
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REF_BLAS defaults to the full path to the netlib BLAS library as
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installed from the appropriate SlackBuilds.org script. If you have
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the netlib BLAS elsewhere, you have to set the appropriate
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value to this variable.
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USE_ARCH_DEFAULTS defaults to "yes", which means that the library
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will be optimized by trying to take into account former builds done
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on a similar machine. Thus ATLAS will use predefined optimizations
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if available. This may reduce (much) the compilation time but may
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not give you the best result if you don't use the same compiler
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version (gcc 4.2) as the ATLAS author.
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Please note that with this variable set to "no", or if there are no
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known optimizations for your machine ATLAS compilation lasts for
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about three hours! Take a nap :-)
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SYS_DESTDIR is set by default to "/usr" and is the system destination
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directory. When installing the package produced by this SlackBuild,
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ATLAS's files will be written to $SYS_DESTDIR/include,
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$SYS_DESTDIR/include/atlas and $SYS_DESTDIR/lib (or lib64).
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Documentation files are written to /usr/doc/atlas-$VERSION if not
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otherwise stated (see below).
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You may want to change the value of SYS_DESTDIR to avoid conflicts (see
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IMPORTANT NOTES above). IMPORTANT: SYS_DESTDIR has to have an absolute
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path as value.
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DEFAULT_DOCS has the default value "yes", which means that docs go
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to /usr/doc/atlas-$VERSION, but you may want to let the docs to
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go to $SYS_DESTDIR/doc/atlas-$VERSION. For this, just set this
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variable to something like "no".
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All these settings may be done the usual way on the command line when
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calling this SlackBuild, you do not have to edit the script.
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If you also installed the LAPACK linked against ATLAS, consider the following:
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"IMPORTANT: If you are actually updating this library, i.e. ATLAS, you MUST also
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rebuild and reinstall LAPACK, even if there is no update available for LAPACK!
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Otherwise you end up with an broken/incomplete LAPACK library!
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