diff options
author | Graham Christensen <graham@grahamc.com> | 2022-09-22 11:17:14 -0400 |
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committer | Graham Christensen <graham@grahamc.com> | 2022-09-22 16:01:23 -0400 |
commit | c2b898da7623a39e3c9b6265d311fe182aa526f0 (patch) | |
tree | 5b55dc2b33259ab9746c1f321a5357939dfcb363 /pkgs/stdenv/generic/setup.sh | |
parent | a3f8caaf613cec9b11971851e07fd9f146d53c94 (diff) |
treewide: drop -l$NIX_BUILD_CORES
Passing `-l$NIX_BUILD_CORES` improperly limits the overall system load. For a build machine which is configured to run `$B` builds where each build gets `total cores / B` cores (`$C`), passing `-l $C` to make will improperly limit the load to `$C` instead of `$B * $C`. This effect becomes quite pronounced on machines with 80 cores, with 40 simultaneous builds and a cores limit of 2. On a machine with this configuration, Nix will run 40 builds and make will limit the overall system load to approximately 2. A build machine with this many cores can happily run with a load approaching 80. A non-solution is to oversubscribe the machine, by picking a larger `$C`. However, there is no way to divide the number of cores in a way which fairly subdivides the available cores when `$B` is greater than 1. There has been exploration of passing a jobserver in to the sandbox, or sharing a jobserver between all the builds. This is one option, but relatively complicated and only supports make. Lots of other software uses its own implementation of `-j` and doesn't support either `-l` or the Make jobserver. For the case of an interactive user machine, the user should limit overall system load using `$B`, `$C`, and optionally systemd's cpu/network/io limiting features. Making this change should significantly improve the utilization of our build farm, and improve the throughput of Hydra.
Diffstat (limited to 'pkgs/stdenv/generic/setup.sh')
-rw-r--r-- | pkgs/stdenv/generic/setup.sh | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh index f0fcb30451dd8..62f9121d73d6b 100644 --- a/pkgs/stdenv/generic/setup.sh +++ b/pkgs/stdenv/generic/setup.sh @@ -1100,7 +1100,7 @@ buildPhase() { # Old bash empty array hack # shellcheck disable=SC2086 local flagsArray=( - ${enableParallelBuilding:+-j${NIX_BUILD_CORES} -l${NIX_BUILD_CORES}} + ${enableParallelBuilding:+-j${NIX_BUILD_CORES}} SHELL=$SHELL $makeFlags "${makeFlagsArray[@]}" $buildFlags "${buildFlagsArray[@]}" @@ -1139,7 +1139,7 @@ checkPhase() { # Old bash empty array hack # shellcheck disable=SC2086 local flagsArray=( - ${enableParallelChecking:+-j${NIX_BUILD_CORES} -l${NIX_BUILD_CORES}} + ${enableParallelChecking:+-j${NIX_BUILD_CORES}} SHELL=$SHELL $makeFlags "${makeFlagsArray[@]}" ${checkFlags:-VERBOSE=y} "${checkFlagsArray[@]}" @@ -1273,7 +1273,7 @@ installCheckPhase() { # Old bash empty array hack # shellcheck disable=SC2086 local flagsArray=( - ${enableParallelChecking:+-j${NIX_BUILD_CORES} -l${NIX_BUILD_CORES}} + ${enableParallelChecking:+-j${NIX_BUILD_CORES}} SHELL=$SHELL $makeFlags "${makeFlagsArray[@]}" $installCheckFlags "${installCheckFlagsArray[@]}" |