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dlib: add flag to disable AVX support

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Especially older hardware doesn't support AVX instructions. DLib is
still functional there, but significantly slower[1].

By setting `avxInstructions` to false, DLib will be compiled without
this feature.

[1] http://dlib.net/compile.html
This commit is contained in:
Maximilian Bosch 2019-03-03 14:21:04 +01:00
parent 77edcf88dc
commit 9732c44225
No known key found for this signature in database
GPG Key ID: 091DBF4D1FC46B8E
3 changed files with 38 additions and 1 deletions
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27
doc/package-notes.xml
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@ -882,6 +882,33 @@ citrix_receiver.override {
On NixOS it can be installed using the following expression:
<programlisting>{ pkgs, ... }: {
fonts.fonts = with pkgs; [ noto-fonts-emoji ];
}</programlisting>
</para>
</section>
</section>
<section xml:id="dlib">
<title>DLib</title>
<para>
<link xlink:href="http://dlib.net/">DLib</link> is a modern, C++-based toolkit which
provides several machine learning algorithms.
</para>
<section xml:id="compiling-without-avx-support">
<title>Compiling without AVX support</title>
<para>
Especially older CPUs don't support
<link xlink:href="https://en.wikipedia.org/wiki/Advanced_Vector_Extensions">AVX</link>
(<abbrev>Advanced Vector Extensions</abbrev>) instructions that are used by DLib to
optimize their algorithms.
</para>
<para>
On the affected hardware errors like <literal>Illegal instruction</literal> will occur.
In those cases AVX support needs to be disabled:
<programlisting>self: super: {
dlib = super.dlib.override { avxSupport = false; };
}</programlisting>
</para>
</section>

5
pkgs/development/libraries/dlib/default.nix
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@ -1,5 +1,8 @@
{ stdenv, lib, fetchFromGitHub, cmake, pkgconfig, libpng, libjpeg
, guiSupport ? false, libX11
# see http://dlib.net/compile.html
, avxSupport ? true
}:
stdenv.mkDerivation rec {
@ -17,6 +20,8 @@ stdenv.mkDerivation rec {
rm -rf dlib/external
'';
cmakeFlags = [ "-DUSE_AVX_INSTRUCTIONS=${if avxSupport then "yes" else "no"}" ];
enableParallelBuilding = true;
nativeBuildInputs = [ cmake pkgconfig ];
buildInputs = [ libpng libjpeg ] ++ lib.optional guiSupport libX11;

7
pkgs/development/python-modules/dlib/default.nix
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@ -1,12 +1,17 @@
{ buildPythonPackage, dlib, python, pytest }:
{ buildPythonPackage, dlib, python, pytest, avxSupport ? true }:
buildPythonPackage {
inherit (dlib) name src nativeBuildInputs buildInputs meta;
# although AVX can be enabled, we never test with it. Some Hydra machines
# fail because of this, however their build results are probably used on hardware
# with AVX support.
checkPhase = ''
${python.interpreter} nix_run_setup test --no USE_AVX_INSTRUCTIONS
'';
setupPyBuildFlags = [ "--${if avxSupport then "yes" else "no"} USE_AVX_INSTRUCTIONS" ];
patches = [ ./build-cores.patch ];
checkInputs = [ pytest ];