The zram module doesn’t seem to working for me. I may dig a little deeper later, but posting this in case anyone has suggestions about what might be wrong.
I just added this configuration.nix and rebooted:
zramSwap = {
enable = true;
algorithm = "zstd";
};
After reboot, swapon -s only lists the devices I had before, and there are no devices named /sys/class/block/zram*.
Poking around, I found something called zram-init-zram0.service and decided to play with it. Initially, zram doesn’t appear anywhere in the output of systemctl, and the status looks like this:
[root@angel:~]# systemctl status zram-init-zram0
● zram-init-zram0.service - Init swap on zram-based device zram0
Loaded: loaded (/nix/store/vrfmjfr3qg2sq75dc1v6amha3xpba37g-unit-zram-init-zram0.service/zram-init-zram0.service; enabled>
Active: inactive (dead)
Then after I manually start it, the status output looks different:
[root@angel:~]# systemctl start zram-init-zram0
[root@angel:~]# systemctl status zram-init-zram0
● zram-init-zram0.service - Init swap on zram-based device zram0
Loaded: loaded (/nix/store/vrfmjfr3qg2sq75dc1v6amha3xpba37g-unit-zram-init-zram0.service/zram-init-zram0.service; enabled>
Active: active (exited) since Thu 2020-04-16 20:25:56 UTC; 1s ago
Process: 2156 ExecStart=/nix/store/b8x52yy9c5q4zrvhflx1wl6mqpr3ivv0-unit-script-zram-init-zram0-start (code=exited, status>
Main PID: 2156 (code=exited, status=0/SUCCESS)
IP: 0B in, 0B out
CPU: 25ms
Apr 16 20:25:56 angel systemd[1]: Starting Init swap on zram-based device zram0...
Apr 16 20:25:56 angel b8x52yy9c5q4zrvhflx1wl6mqpr3ivv0-unit-script-zram-init-zram0-start[2156]: Setting up swapspace version>
Apr 16 20:25:56 angel b8x52yy9c5q4zrvhflx1wl6mqpr3ivv0-unit-script-zram-init-zram0-start[2156]: no label, UUID=441a72a6-d812>
Apr 16 20:25:56 angel systemd[1]: Started Init swap on zram-based device zram0.
I don’t know whether zram-init-zram0 is the service that’s actually supposed to add the swap space, but in any case swapon -s still doesn’t show any zram. Finally, if I manually run swapon -p 5 /dev/zram0 it does appear in the output of swapon -s.
Any idea where to look next? By default I guess my next step would either be be to see if I can reproduce the problem with nixos-rebuild build-vm, or to learn more about how the NixOS zram module works so I actually know what should be happening.
Here’s my configuration.nix:
{ config, pkgs, ... }:
{
imports =
[ # Include the results of the hardware scan.
./hardware-configuration.nix
];
boot = {
initrd = {
luks.devices = {
# nixos-generate-config puts SfricBtrSec into
# hardware-configuration.nix but not KFricBtrSec. I don't know why.
KFricBtrSec = { device = "/dev/disk/by-uuid/dab9a0f9-c45d-4e4f-8157-18c67518f955"; };
};
supportedFilesystems = [ "btrfs" ];
};
loader.grub = {
enable = true;
version = 2;
device = "/dev/sdb";
};
};
environment.systemPackages = [ pkgs.manpages ];
fileSystems =
let btrfsOptions = [ "autodefrag" "noatime" ]; in
{
"/".options = btrfsOptions;
"/btr".options = btrfsOptions;
"/home".options = btrfsOptions;
# boot.tmpOnTmpfs doesn't allow the size to be configured.
"/tmp" = {
fsType = "tmpfs";
device = "tmpfs";
# Options based on output of mount | grep /tmp with boot.tmpOnTmpfs
# option --- I'm trying to mimic that. size option added.
options = [ "nosuid" "nodev" "size=32G" ];
};
};
networking = {
extraHosts = ''
10.167.0.1 sylph
fc00:f69a:9457:2800::1 sylph
10.167.0.3 copter
fc00:f69a:9457:2800::3 copter
10.167.0.4 angel
fc00:f69a:9457:2800::4 angel
10.167.0.6 moth
fc00:f69a:9457:2800::6 moth
'';
hostName = "angel";
interfaces."tinc.falsifian" = {
ipv4.addresses = [ { address = "10.167.0.4"; prefixLength = 16; } ];
ipv6.addresses = [ { address = "fc00:f69a:9457:2800:0:0:0:4"; prefixLength = 64; } ];
};
# The global useDHCP flag is deprecated, therefore explicitly set to false here.
# Per-interface useDHCP will be mandatory in the future.
useDHCP = false;
interfaces.enp3s0.useDHCP = true;
interfaces."tinc.falsifian".useDHCP = false;
interfaces.wlp4s6.useDHCP = false;
};
nix = {
daemonIONiceLevel = 5;
daemonNiceLevel = 10;
gc = {
# This slows down the system too much (as of 2020-03-28). Maybe if it
# were changed to use nice it would be okay.
automatic = false;
};
};
i18n = {
defaultLocale = "en_CA.UTF-8";
};
time.timeZone = "Etc/UTC";
security.sudo.wheelNeedsPassword = false;
services = {
openssh.enable = true;
printing = {
drivers = [ pkgs.gutenprint ];
enable = true;
};
tinc.networks.falsifian = {
extraConfig = "ConnectTo = sylph";
hosts = {
angel = ''
Port = 43128
Subnet = 10.167.0.4
Subnet = fc00:f69a:9457:2800:0:0:0:4
'';
moth = ''
Subnet = 10.167.0.6
Subnet = fc00:f69a:9457:2800:0:0:0:6
Ed25519PublicKey = Os6RhCSPs+PlTr8wq9VUpU0PPgTYszsZRik3k+EKUOC
-----BEGIN RSA PUBLIC KEY-----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==
-----END RSA PUBLIC KEY-----
'';
sylph = ''
Address = 50.16.203.136
Subnet = 10.167.0.1
Subnet = fc00:f69a:9457:2800:0:0:0:1
-----BEGIN RSA PUBLIC KEY-----
MIIBCgKCAQEAv17ZOV632hTtJR4kLjE3i3bNr4HLMh+9Ohm7mrr2mF2tb07XOKuo
S3DwtmfbzgnnBIuVXhhdP2j22yDBPBIq+MsBXGag+xZWjbO4a9CV6weqZ2DYGaPL
X4tYeQds6LpiKR/+aXmbGYdvc9AYyECnfY0jXM1XS2I8PA8SPl5KVc3Yxrlcz0lv
/4ph85HmSizQObamb0rxm3ifYRZ4n6V3zeGXYnzREVMWN2Fko4ke7J5TBBGODApj
Rldav10jNuUBY5s8ffitbMBEsQ4LAXgL9bvkKBnG0d+fY4TdvaGVxqh3ppB+nEkW
1vPRvW7A1BUxXQoaGUNM/AGJjsqkP9jj4wIDAQAB
-----END RSA PUBLIC KEY-----
'';
};
name = "angel";
};
# Use bfq scheduler since it respects ionice.
#
# udev rule based on https://releases.nixos.org/nix-dev/2016-November/022137.html
udev.extraRules = ''ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/scheduler}="bfq"'';
xserver = {
desktopManager.plasma5.enable = true;
displayManager.sddm.enable = true;
enable = true;
};
};
# nixos-generate-config puts /dev/disk/by-uuid/something into swapDevices,
# which is unhelpful because I want the randomEncryption option. I think the
# uuid will exist anyway since I think it will be different on every boot. So
# use pkgs.lib.mkForce to override it instead of merging this list with it.
swapDevices = pkgs.lib.mkForce [
{
device = "/dev/disk/by-partuuid/1a2a682c-5001-4088-922e-70819ed67f37";
priority = 0;
randomEncryption.enable = true;
}
{
device = "/dev/disk/by-partuuid/5bbdff04-7dbe-4948-ac88-0797b60b9971";
priority = 0;
randomEncryption.enable = true;
}
];
users.users = {
colin =
{ createHome = true;
home = "/home/colin";
isNormalUser = true;
};
james = {
isNormalUser = true;
extraGroups = [ "wheel" ]; # Enable ‘sudo’ for the user.
};
};
zramSwap = {
enable = true;
algorithm = "zstd";
};
# This value determines the NixOS release from which the default
# settings for stateful data, like file locations and database versions
# on your system were taken. It‘s perfectly fine and recommended to leave
# this value at the release version of the first install of this system.
# Before changing this value read the documentation for this option
# (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
system.stateVersion = "20.03"; # Did you read the comment?
}
and hardware-configuration.nix:
# Do not modify this file! It was generated by ‘nixos-generate-config’
# and may be overwritten by future invocations. Please make changes
# to /etc/nixos/configuration.nix instead.
{ config, lib, pkgs, ... }:
{
imports =
[ <nixpkgs/nixos/modules/installer/scan/not-detected.nix>
];
boot.initrd.availableKernelModules = [ "ahci" "ohci_pci" "ehci_pci" "pata_atiixp" "pata_jmicron" "firewire_ohci" "usbhid" "sd_mod" ];
boot.initrd.kernelModules = [ ];
boot.kernelModules = [ "kvm-amd" ];
boot.extraModulePackages = [ ];
fileSystems."/" =
{ device = "/dev/mapper/SFricBtrSec";
fsType = "btrfs";
options = [ "subvol=nixos_root" ];
};
boot.initrd.luks.devices."SFricBtrSec".device = "/dev/disk/by-uuid/cc82b84c-b312-44cf-a2cf-2e5e9c5a8d20";
fileSystems."/btr" =
{ device = "/dev/mapper/SFricBtrSec";
fsType = "btrfs";
};
fileSystems."/home" =
{ device = "/dev/mapper/SFricBtrSec";
fsType = "btrfs";
options = [ "subvol=home" ];
};
fileSystems."/boot" =
{ device = "/dev/disk/by-uuid/4a621c7a-c1f9-4ce1-a0e5-8acdde829dae";
fsType = "ext2";
};
swapDevices =
[ { device = "/dev/disk/by-uuid/f709186b-5015-47d5-a229-2e1e29546f6a"; }
];
nix.maxJobs = lib.mkDefault 3;
# High-DPI console
console.font = lib.mkDefault "${pkgs.terminus_font}/share/consolefonts/ter-u28n.psf.gz";
}