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nixos/sysctl: dynamic inotify watches or higher defaults #126777

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nixos/sysctl: dynamic inotify watches or higher defaults #126777

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16 changes: 16 additions & 0 deletions nixos/modules/config/sysctl.nix
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Expand Up @@ -59,5 +59,21 @@ in
# Disable YAMA by default to allow easy debugging.
boot.kernel.sysctl."kernel.yama.ptrace_scope" = mkDefault 0;

# Dynamic since kernel v5.12
# https://github.com/torvalds/linux/commit/ac7b79fd190b02e7151bc7d2b9da692f537657f3
# From version 5.12 inotify instances are charegd memcg, so to let memcg work
# properly in all possible circumstance, kernel mainatainers (see commit) suggest
# to make this value ineffective by setting it to the maximum
boot.kernel.sysctl."fs.inotify.max_user_instances" =
if (config.boot.kernelPackages.kernel.kernelAtLeast "5.12")
then mkDefault 2147483647 # INT_MAX, dynamically limited based on available memory
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Can we make boot.kernel.INT_MAX a variable?

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I guess, it would be more like in the stdenv, though or lib or even builtin. I can make a quick follow-up PR once this is merged.

else mkDefault 8192; # instead of 128

# Dynamic since kernel v5.11
# https://github.com/torvalds/linux/commit/92890123749bafc317bbfacbe0a62ce08d78efb7
boot.kernel.sysctl."fs.inotify.max_user_watches" = mkIf
(config.boot.kernelPackages.kernel.kernelOlder "5.11")
(mkDefault 1048576); # instead of 8192

};
}
6 changes: 0 additions & 6 deletions nixos/modules/services/x11/xserver.nix
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Expand Up @@ -663,12 +663,6 @@ in
icons.enable = true;
};

# The default max inotify watches is 8192.
# Nowadays most apps require a good number of inotify watches,
# the value below is used by default on several other distros.
boot.kernel.sysctl."fs.inotify.max_user_instances" = mkDefault 524288;
boot.kernel.sysctl."fs.inotify.max_user_watches" = mkDefault 524288;

systemd.defaultUnit = mkIf cfg.autorun "graphical.target";

systemd.services.display-manager =
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2 changes: 0 additions & 2 deletions nixos/modules/virtualisation/lxd.nix
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Expand Up @@ -167,8 +167,6 @@ in {

boot.kernel.sysctl = mkIf cfg.recommendedSysctlSettings {
"fs.inotify.max_queued_events" = 1048576;
"fs.inotify.max_user_instances" = 1048576;
"fs.inotify.max_user_watches" = 1048576;
"vm.max_map_count" = 262144;
"kernel.dmesg_restrict" = 1;
"net.ipv4.neigh.default.gc_thresh3" = 8192;
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