Power Management: Difference between revisions

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~~{{expansion}}~~

This article covers configurations related to power management in terms of energy saving modes of various devices and components.

== ~~Suspend~~ ==

== Configuration ==

=== Hard drives ===

Following snippet configures [[Udev]] rules which automatically run the program <code>hdparm</code> to enable power saving modes for hard disks, especially rotational drives mapped to <code>/dev/sd*</code>.<syntaxhighlight lang="nix">

services.udev.extraRules =

let

mkRule = as: lib.concatStringsSep ", " as;

mkRules = rs: lib.concatStringsSep "\n" rs;

in mkRules ([( mkRule [

''ACTION=="add|change"''

''SUBSYSTEM=="block"''

''KERNEL=="sd[a-z]"''

''ATTR{queue/rotational}=="1"''

''RUN+="${pkgs.hdparm}/bin/hdparm -B 90 -S 41 /dev/%k"''

])]);

</syntaxhighlight>The <code>hdparm</code> parameters <code>-B</code> and <code>-S</code> define power saving modes and in case of <code>-S</code> the standby (spindown) timeout. The number 41 means therefore: Turn off the motor after 205 = 41*5 seconds.

=== Suspend hooks ===

NixOS provides the {{nixos:option|powerManagement.resumeCommands}} option which defines commands that are added to a global script that will be executed after resuming.

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</syntaxhighlight>

== Hibernation ==

=== Hibernation ===

Hibernation requires a configured swap device. See [https://nixos.org/manual/nixos/stable/#ch-installation installation instructions] on how to create a swap partition. An example configuration could look like this:<syntaxhighlight lang="nix">

Hibernation requires a configured swap device. See [https://nixos.org/manual/nixos/stable/#ch-installation installation instructions] on how to create a swap partition.

Please note that <code>resumeDevice</code> must match the output of <code>swapon -s</code> especially if you're dealing with mapped volumes (LUKS, logical volumes, logical volumes under LUKS, etc.). If you're using a swapfile, you must also [https://search.nixos.org/options?channel=unstable&show=boot.resumeDevice&from=0&size=50&sort=relevance&type=packages&query=resume+offset specify the offset to it.]

Therefore, an example configuration could look like this:<syntaxhighlight lang="nix">

/*

I'm hibernating into a logical volume that's also under LUKS. Pretty cool, right?

*/

swapDevices = [

{

device = "/dev/~~hda7~~";

device = "/dev/VG/SWAP";

}

];

~~boot.resumeDevice = "/dev/hda7";~~

~~</syntaxhighlight>Please note that encrypted swap devices or swap files are not yet supported for hibernation.~~

Test and use hibernation with following command:<syntaxhighlight lang="nix">

boot.resumeDevice = "/dev/dm-7";

</syntaxhighlight>Derived from a system with the following output from <code>swapon -s</code> :<syntaxhighlight>

Filename Type Size Used Priority

/dev/dm-7 partition 67108860 00

/dev/zram0 partition 32881148 032767

</syntaxhighlight>

Test and use hibernation with the following command:<syntaxhighlight lang="nix">

systemctl hibernate

</syntaxhighlight>

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systemd.sleep.extraConfig = ''

HibernateDelaySec=1h

'';

</syntaxhighlight>

Or, to disable suspend entirely, consider a configuration like this:

systemd.sleep.extraConfig = ''

AllowSuspend=no

AllowHibernation=no

AllowHybridSleep=no

AllowSuspendThenHibernate=no

'';

</syntaxhighlight>

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* {{manual:nixos|sec=#sec-rebooting|chapter=Chapter 23. Rebooting and Shutting Down}}

[[Category:Configuration]]

@@ Line 1: / Line 1: @@
-{{expansion}}
+This article covers configurations related to power management in terms of energy saving modes of various devices and components.
-== Suspend ==
+== Configuration ==
+=== Hard drives ===
+Following snippet configures [[Udev]] rules which automatically run the program <code>hdparm</code> to enable power saving modes for hard disks, especially rotational drives mapped to <code>/dev/sd*</code>.<syntaxhighlight lang="nix">
+services.udev.extraRules =
+  let
+    mkRule = as: lib.concatStringsSep ", " as;
+    mkRules = rs: lib.concatStringsSep "\n" rs;
+  in mkRules ([( mkRule [
+    ''ACTION=="add|change"''
+    ''SUBSYSTEM=="block"''
+    ''KERNEL=="sd[a-z]"''
+    ''ATTR{queue/rotational}=="1"''
+    ''RUN+="${pkgs.hdparm}/bin/hdparm -B 90 -S 41 /dev/%k"''
+  ])]);
+</syntaxhighlight>The <code>hdparm</code> parameters <code>-B</code> and <code>-S</code> define power saving modes and in case of <code>-S</code> the standby (spindown) timeout. The number 41 means therefore: Turn off the motor after 205 = 41*5 seconds.
 === Suspend hooks ===
 NixOS provides the {{nixos:option|powerManagement.resumeCommands}} option which defines commands that are added to a global script that will be executed after resuming.
@@ Line 27: / Line 41: @@
 </syntaxhighlight>
-== Hibernation ==
+=== Hibernation ===
-Hibernation requires a configured swap device. See [https://nixos.org/manual/nixos/stable/#ch-installation installation instructions] on how to create a swap partition. An example configuration could look like this:<syntaxhighlight lang="nix">
+Hibernation requires a configured swap device. See [https://nixos.org/manual/nixos/stable/#ch-installation installation instructions] on how to create a swap partition.
+Please note that <code>resumeDevice</code> must match the output of  <code>swapon -s</code> especially if you're dealing with mapped volumes (LUKS, logical volumes, logical volumes under LUKS, etc.). If you're using a swapfile, you must also [https://search.nixos.org/options?channel=unstable&show=boot.resumeDevice&from=0&size=50&sort=relevance&type=packages&query=resume+offset specify the offset to it.]
+Therefore, an example configuration could look like this:<syntaxhighlight lang="nix">
+/*
+  I'm hibernating into a logical volume that's also under LUKS. Pretty cool, right?
+*/
 swapDevices = [
    {
-     device = "/dev/hda7";
+     device = "/dev/VG/SWAP";
    }
 ];
-boot.resumeDevice = "/dev/hda7";
-</syntaxhighlight>Please note that encrypted swap devices or swap files are not yet supported for hibernation.
-Test and use hibernation with following command:<syntaxhighlight lang="nix">
+boot.resumeDevice = "/dev/dm-7";
+</syntaxhighlight>Derived from a system with the following output from <code>swapon -s</code> :<syntaxhighlight>
+Filename                                Type            Size           Used             Priority
+/dev/dm-7                               partition       67108860       00
+/dev/zram0                              partition       32881148       032767
+</syntaxhighlight>
+Test and use hibernation with the following command:<syntaxhighlight lang="nix">
 systemctl hibernate
 </syntaxhighlight>
@@ Line 47: / Line 76: @@
 systemd.sleep.extraConfig = ''
    HibernateDelaySec=1h
+'';
+</syntaxhighlight>
+Or, to disable suspend entirely, consider a configuration like this:
+<syntaxhighlight lang="nix">
+systemd.sleep.extraConfig = ''
+  AllowSuspend=no
+  AllowHibernation=no
+  AllowHybridSleep=no
+  AllowSuspendThenHibernate=no
 '';
 </syntaxhighlight>
@@ Line 123: / Line 162: @@
 * {{manual:nixos|sec=#sec-rebooting|chapter=Chapter 23. Rebooting and Shutting Down}}
+[[Category:Configuration]]