37 lines
1.3 KiB
Nix
37 lines
1.3 KiB
Nix
{ config, lib, pkgs, modulesPath, ... }:
|
||
|
||
{
|
||
config = lib.mkIf config.boot.zfs.enabled {
|
||
systemd.services."zfs-arc-limit" = {
|
||
description = "Set ZFS ARC max to 20% of physical RAM";
|
||
# Ensure the module is loaded before we write to /sys
|
||
after = [ "systemd-modules-load.service" ];
|
||
# Run early, but it’s fine if ZFS has already imported; the limit still applies
|
||
wantedBy = [ "multi-user.target" ];
|
||
path = [ pkgs.gawk ];
|
||
script = ''
|
||
set -euo pipefail
|
||
# Total RAM in kB
|
||
mem_kb=$(awk '/MemTotal:/ {print $2}' /proc/meminfo)
|
||
echo "DEBUG: Total RAM: $mem_kb kB"
|
||
# 20%, in bytes
|
||
arc_max_bytes=$(( mem_kb * 1024 / 100 * 20 ))
|
||
echo "DEBUG: Setting ZFS ARC max to: $arc_max_bytes bytes"
|
||
param="/sys/module/zfs/parameters/zfs_arc_max"
|
||
if [ -w "$param" ]; then
|
||
echo "DEBUG: Writing to $param"
|
||
echo "$arc_max_bytes" > "$param"
|
||
echo "DEBUG: ZFS ARC max successfully set"
|
||
else
|
||
echo "WARN: $param not writable; is the zfs module loaded?" >&2
|
||
exit 0
|
||
fi
|
||
'';
|
||
serviceConfig = {
|
||
Type = "oneshot";
|
||
RemainAfterExit = true;
|
||
};
|
||
};
|
||
boot.zfs.forceImportRoot = false; # New default in 26.11
|
||
};
|
||
} |