83 lines
2.3 KiB
Nix
83 lines
2.3 KiB
Nix
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{ ... }: { lib, pkgs, ... }: {
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boot.kernelParams = [
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"zswap.zpool=zsmalloc"
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"zram.num_devices=0"
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];
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boot.kernel.sysctl = {
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"vm.page-cluster" = lib.mkDefault 0;
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"vm.swappiness" = lib.mkDefault 180;
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"vm.watermark_boost_factor" = lib.mkDefault 0;
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"vm.watermark_scale_factor" = lib.mkDefault 125;
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};
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systemd.services.zram-swap =
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let
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writeShell = { name, text, runtimeInputs ? [ ] }:
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pkgs.writeShellApplication { inherit name text runtimeInputs; } + "/bin/${name}";
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in {
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description = "Compressed in-memory swap space";
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wantedBy = [ "swap.target" ];
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unitConfig.DefaultDependencies = false;
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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RuntimeDirectory = "zram-swap";
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CapabilityBoundingSet = [ "CAP_DAC_OVERRIDE" "CAP_SYS_ADMIN" ];
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SystemCallFilter = [ "@system-service" "@swap" ];
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ExecStartPre = writeShell {
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name = "zram-swap-start-pre";
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runtimeInputs = with pkgs; [ coreutils getconf util-linux ];
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text = ''
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pages="$(getconf _PHYS_PAGES)"
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pagesize="$(getconf PAGESIZE)"
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dev="$(cat /sys/class/zram-control/hot_add)"
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echo "$dev" >"$RUNTIME_DIRECTORY/device"
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echo zstd >"/sys/block/zram$dev/comp_algorithm"
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echo "$((pages * pagesize * 3 / 2))" >"/sys/block/zram$dev/disksize"
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echo "$((pages * pagesize * 3 / 4))" >"/sys/block/zram$dev/mem_limit"
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mkswap "/dev/zram$dev"
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'';
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};
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ExecStart = writeShell {
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name = "zram-swap-start";
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runtimeInputs = with pkgs; [ util-linux ];
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text = ''
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swapon --discard --priority 32767 "/dev/zram$(<"$RUNTIME_DIRECTORY/device")"
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'';
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};
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ExecStop = writeShell {
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name = "zram-swap-stop";
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runtimeInputs = with pkgs; [ util-linux ];
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text = ''
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swapoff "/dev/zram$(<"$RUNTIME_DIRECTORY/device")"
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'';
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};
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ExecStopPost = writeShell {
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name = "zram-swap-stop-post";
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runtimeInputs = with pkgs; [ coreutils ];
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text = ''
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test -s "$RUNTIME_DIRECTORY/device" || exit 0
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dev="$(<"$RUNTIME_DIRECTORY/device")"
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echo 1 >"/sys/block/zram$dev/reset"
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echo "$dev" >/sys/class/zram-control/hot_remove
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rm -f -- "$RUNTIME_DIRECTORY/device"
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'';
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};
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};
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};
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}
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