nixpkgs/nixos/modules/hardware/ksm.nix

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{ config, lib, ... }:
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with lib;
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let
cfg = config.hardware.ksm;
in {
imports = [
(mkRenamedOptionModule [ "hardware" "enableKSM" ] [ "hardware" "ksm" "enable" ])
];
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options.hardware.ksm = {
enable = mkEnableOption "Kernel Same-Page Merging";
sleep = mkOption {
type = types.nullOr types.int;
default = null;
description = ''
How many milliseconds ksmd should sleep between scans.
Setting it to <literal>null</literal> uses the kernel's default time.
'';
};
};
config = mkIf cfg.enable {
systemd.services.enable-ksm = {
description = "Enable Kernel Same-Page Merging";
wantedBy = [ "multi-user.target" ];
after = [ "systemd-udev-settle.service" ];
script = ''
if [ -e /sys/kernel/mm/ksm ]; then
echo 1 > /sys/kernel/mm/ksm/run
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${optionalString (cfg.sleep != null) ''echo ${toString cfg.sleep} > /sys/kernel/mm/ksm/sleep_millisecs''}
fi
'';
};
};
}