| 26 Jun 2026 |
 emily | because it sets a bunch of other stuff too | 13:48:12 |
| emily | admittedly "tell you're about to do OpenMP stuff" might be complicated | 13:48:34 |
 dramforever | openmp and mpi are almost unrelated | 13:48:47 |
| dramforever | might explain why | 13:48:59 |
| emily | well | 13:49:06 |
| emily | mpiCheckPhaseHook sets OMP_NUM_THREADS | 13:49:11 |
| emily | so maybe I'm not the only one confused by this :P | 13:49:23 |
| dramforever | might explain why stuff aren't using it i mean | 13:49:23 |
 Grimmauld (any/all) | okay other idea | 13:49:41 |
| emily | all of these things have to be depending on OpenMP already right? couldn't we just put a setup hook on OpenMP itself to set the var | 13:49:54 |
| Grimmauld (any/all) | it might not depend directly. Biggest problem has been python things running via numpy/scipy | 13:50:51 |
| emily | give those a setup hook then? :) | 13:51:12 |
 Vladimír Čunát | The variable shouldn't hurt to have everywhere in builds (by default), no? | 13:51:33 |
 hexa | and they do it via blas I think | 13:51:43 |
| Vladimír Čunát | * The variable shouldn't hurt to have everywhere in builds (by default), no? Or possibly just in the check phases. | 13:52:29 |
| emily | probably not, and I could see an argument for "we should just set every relevant environment variable for ~everything in stdenv". but that might be an annoying practice to follow in general, e.g. would turn various kinds of flag changes into world rebuilds. and then it doesn't scale if you also need to say, point something at a path or whatever (which mpiCheckPhaseHook also happens to do) | 13:53:02 |
| Grimmauld (any/all) | add mpiCheckPhaseHook to blas propagatedBuildInputs ? | 13:53:08 |
| emily | so feels like doing it closer to the problem makes sense by default | 13:53:25 |
| emily | not sure what it is with Python things and using all the cores all the time | 13:53:52 |
| hexa | default numpy/scipy behavior | 13:54:10 |
| hexa | they scale right up | 13:54:16 |
| Grimmauld (any/all) | python has checks-by-default, and numpy/scipy abstracts away the compute cost of tests | 13:54:20 |
| emily | right | 13:54:25 |
| hexa | the real deal would be faking nproc for builds | 13:55:03 |
| emily | probably just adding setup hooks to those is sufficient then? or the Python check phase could yell at you if it sees them in the dep graph but not a corresponding hook… | 13:55:18 |
| Vladimír Čunát | IIRC cgroups only allow you to pin to particular subset of cores. | 13:56:24 |
| Vladimír Čunát | * IIRC cgroups only allow you to restrict to particular subset of cores. | 13:56:43 |
| Vladimír Čunát | * IIRC cgroups only allow you to restrict to a particular subset of cores. | 13:56:50 |
| emily | the real real deal would be NumPy supporting jobserver protocol and also jobserver protocol being good | 13:56:55 |
| Grimmauld (any/all) | diff --git a/pkgs/by-name/bl/blas/package.nix b/pkgs/by-name/bl/blas/package.nix
index 01ad1839c339..85e2e2cb3412 100644
--- a/pkgs/by-name/bl/blas/package.nix
+++ b/pkgs/by-name/bl/blas/package.nix
@@ -3,6 +3,7 @@
stdenv,
lapack-reference,
openblas,
+ mpiCheckPhaseHook,
isILP64 ? false,
blasProvider ? openblas,
}:
@@ -186,6 +187,10 @@ stdenv.mkDerivation {
"dev"
];
+ propagatedBuildInputs = [
+ mpiCheckPhaseHook
+ ];
+
meta = (blasProvider'.meta or { }) // {
description = "${lib.getName blasProvider} with just the BLAS C and FORTRAN ABI";
};
diff --git a/pkgs/development/python-modules/numpy/2.nix b/pkgs/development/python-modules/numpy/2.nix
index 67c60475fd5f..0fc2a30f3555 100644
--- a/pkgs/development/python-modules/numpy/2.nix
+++ b/pkgs/development/python-modules/numpy/2.nix
@@ -91,7 +91,6 @@ buildPythonPackage (finalAttrs: {
# see https://github.com/OpenMathLib/OpenBLAS/issues/2993
preConfigure = ''
sed -i 's/-faltivec//' numpy/distutils/system_info.py
- export OMP_NUM_THREADS=$((NIX_BUILD_CORES > 64 ? 64 : NIX_BUILD_CORES))
'';
buildInputs = [
diff --git a/pkgs/development/python-modules/scipy/default.nix b/pkgs/development/python-modules/scipy/default.nix
index cdecd986e4ef..30999320f1e8 100644
--- a/pkgs/development/python-modules/scipy/default.nix
+++ b/pkgs/development/python-modules/scipy/default.nix
@@ -190,11 +190,6 @@ buildPythonPackage (finalAttrs: {
'';
preCheck = ''
- export OMP_NUM_THREADS=$(( $NIX_BUILD_CORES / 4 ))
- if [ $OMP_NUM_THREADS -eq 0 ]; then
- export OMP_NUM_THREADS=1
- fi
-
cd $out
'';
i guess? | 13:57:17 |
