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author | Matthew Bauer <mjbauer95@gmail.com> | 2020-04-21 11:03:10 -0500 |
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committer | Matthew Bauer <mjbauer95@gmail.com> | 2020-04-21 11:03:10 -0500 |
commit | 3c41d61514029d5aa4ea748c1e46098767ae448b (patch) | |
tree | 8830180c68f0dc03a7dd03bf982cdcbce89ee868 /doc | |
parent | 8f58fa044dca8becdc865c2feb51e5048bf14fef (diff) | |
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doc/overlays.xml: update documentation for BLAS/LAPACK
This expands the documentation and explains how to assert LP64.
Diffstat (limited to 'doc')
-rw-r--r-- | doc/languages-frameworks/python.section.md | 29 | ||||
-rw-r--r-- | doc/using/overlays.xml | 40 |
2 files changed, 42 insertions, 27 deletions
diff --git a/doc/languages-frameworks/python.section.md b/doc/languages-frameworks/python.section.md index f8884785e90..e6f0b64fa9c 100644 --- a/doc/languages-frameworks/python.section.md +++ b/doc/languages-frameworks/python.section.md @@ -1290,32 +1290,9 @@ self: super: { ### How to use Intel's MKL with numpy and scipy? -A `site.cfg` is created that configures BLAS based on the `blas` parameter of -the `numpy` derivation. By passing in `mkl`, `numpy` and packages depending on -`numpy` will be built with `mkl`. - -The following is an overlay that configures `numpy` to use `mkl`: - -```nix -self: super: { - python37 = super.python37.override { - packageOverrides = python-self: python-super: { - numpy = python-super.numpy.override { - blas = super.pkgs.mkl; - }; - }; - }; -} -``` - -`mkl` requires an `openmp` implementation when running with multiple processors. -By default, `mkl` will use Intel's `iomp` implementation if no other is -specified, but this is a runtime-only dependency and binary compatible with the -LLVM implementation. To use that one instead, Intel recommends users set it with -`LD_PRELOAD`. - -Note that `mkl` is only available on `x86_64-{linux,darwin}` platforms; -moreover, Hydra is not building and distributing pre-compiled binaries using it. +MKL can be configured using an overlay. See the section “[Using +overlays to configure +alternatives](#sec-overlays-alternatives-blas-lapack)”. ### What inputs do `setup_requires`, `install_requires` and `tests_require` map to? diff --git a/doc/using/overlays.xml b/doc/using/overlays.xml index 7732e0ac217..5f808839dd0 100644 --- a/doc/using/overlays.xml +++ b/doc/using/overlays.xml @@ -177,7 +177,7 @@ self: super: <para> <link xlink:href="https://software.intel.com/en-us/mkl">Intel - MKL</link> (only works on x86 architecture) + MKL</link> (only works on x86 architecture, unfree) </para> <para> The Nixpkgs attribute is <literal>mkl</literal>. @@ -211,6 +211,44 @@ self: super: using <literal>LD_PRELOAD</literal> of libblas.so.3 and liblapack.so.3. </para> + <para> + Intel MKL requires an <literal>openmp</literal> implementation + when running with multiple processors. By default, + <literal>mkl</literal> will use Intel’s <literal>iomp</literal> + implementation if no other is specified, but this is a + runtime-only dependency and binary compatible with the LLVM + implementation. To use that one instead, Intel recommends users + set it with <literal>LD_PRELOAD</literal>. Note that + <literal>mkl</literal> is only available on + <literal>x86_64-linux</literal> and + <literal>x86_64-darwin</literal>. Moreover, Hydra is not build + and distributing pre-compiled binaries using it. + </para> + <para> + For BLAS/LAPACK switching to work correctly, all packages must + depend on <literal>blas</literal> or <literal>lapack</literal>. + This ensures that only one BLAS/LAPACK library is used at one + time. There are two versions versions of BLAS/LAPACK currently + in the wild, <literal>LP64</literal> (integer size = 32 bits) + and <literal>ILP64</literal> (integer size = 64 bits). Some + software needs special flags or patches to work with + <literal>ILP64</literal>. You can check if + <literal>ILP64</literal> is used in Nixpkgs with + <varname>blas.isILP64</varname> and + <varname>lapack.isILP64</varname>. Some software does NOT work + with <literal>ILP64</literal>, and derivations need to specify + an assertion to prevent this. You can prevent + <literal>ILP64</literal> from being used with the following: + </para> + <programlisting> +{ stdenv, blas, lapack, ... }: + +assert (!blas.isILP64) && (!lapack.isILP64); + +stdenv.mkDerivation { + ... +} + </programlisting> </section> </section> </chapter> |