Difference between revisions of "Power management/Suspend and hibernate"

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[[Category:Power management]]
 
[[Category:Power management]]
{{Article summary start}}
+
[[ja:サスペンドとハイバネート]]
{{Article summary text|Describes suspending (suspend-to-RAM) and hibernating (suspend-to-disk) the system.}}
+
{{Related articles start}}
{{Article summary heading|Related articles}}
+
{{Related|Uswsusp}}
{{Article summary wiki|Uswsusp}}
+
{{Related|TuxOnIce}}
{{Article summary wiki|TuxOnIce}}
+
{{Related|systemd}}
{{Article summary wiki|systemd}}
+
{{Related|pm-utils}}
{{Article summary wiki|pm-utils}}
+
{{Related|hibernate-script}}
{{Article summary wiki|Suspending to RAM with hibernate-script}}
+
{{Related|Power management}}
{{Article summary wiki|Suspending to Disk with hibernate-script}}
+
{{Related articles end}}
{{Article summary end}}
+
Currently there are three methods of suspending available: '''suspend to RAM''' (usually called just '''suspend'''), '''suspend to disk''' (usually known as '''hibernate'''), and '''hybrid suspend''' (sometimes aptly called '''suspend to both'''):
Currently there are available three methods of suspending: '''suspend to RAM''' (usually called just '''suspend'''), '''suspend to disk''' (usually known as '''hibernate'''), and '''hybrid suspend''' (sometimes aptly called '''suspend to both'''):
+
  
 
* '''Suspend to RAM''' method cuts power to most parts of the machine aside from the RAM, which is required to restore the machine's state. Because of the large power savings, it is advisable for laptops to automatically enter this mode when the computer is running on batteries and the lid is closed (or the user is inactive for some time).
 
* '''Suspend to RAM''' method cuts power to most parts of the machine aside from the RAM, which is required to restore the machine's state. Because of the large power savings, it is advisable for laptops to automatically enter this mode when the computer is running on batteries and the lid is closed (or the user is inactive for some time).
  
* '''Suspend to disk''' method saves the machine's state into [[Swap|swap space]] and completely powers off the machine. When the machine is powered on, the state is restored. Until then, there is zero power consumption.
+
* '''Suspend to disk''' method saves the machine's state into [[swap space]] and completely powers off the machine. When the machine is powered on, the state is restored. Until then, there is zero power consumption.
  
 
* '''Suspend to both''' method saves the machine's state into swap space, but does not power off the machine. Instead, it invokes usual suspend to RAM. Therefore, if the battery is not depleted, the system can resume from RAM. If the battery is depleted, the system can be resumed from disk, which is much slower than resuming from RAM, but the machine's state has not been lost.
 
* '''Suspend to both''' method saves the machine's state into swap space, but does not power off the machine. Instead, it invokes usual suspend to RAM. Therefore, if the battery is not depleted, the system can resume from RAM. If the battery is depleted, the system can be resumed from disk, which is much slower than resuming from RAM, but the machine's state has not been lost.
Line 22: Line 21:
 
== Low level interfaces ==
 
== Low level interfaces ==
  
Though these interfaces can be used directly, it is advisable to use some of [[#High level interfaces|high level interfaces]] to suspend/hibernate. Using low level interfaces directly is significantly faster using any high level interface, since running all the pre- and post-suspend hooks takes time, but hooks can properly set hardware clock, restore wireless etc.
+
Though these interfaces can be used directly, it is advisable to use some of [[#High level interfaces|high level interfaces]] to suspend/hibernate. Using low level interfaces directly is significantly faster than using any high level interface, since running all the pre- and post-suspend hooks takes time, but hooks can properly set hardware clock, restore wireless etc.
  
 
=== kernel (swsusp) ===
 
=== kernel (swsusp) ===
Line 48: Line 47:
 
=== systemd ===
 
=== systemd ===
  
[[systemd]] provides native commands for suspend, hibernate and a hybrid suspend, see [[Power Management#Power management with systemd]] for details.
+
[[systemd]] provides native commands for suspend, hibernate and a hybrid suspend, see [[Power management#Power management with systemd]] for details. This is the default interface used in Arch Linux.
  
See [[Power Management#Sleep hooks]] for additional information on configuring suspend/hibernate hooks. Also see {{ic|man systemctl}}, {{ic|man systemd-sleep}}, and {{ic|man systemd.special}}.
+
See [[Power management#Sleep hooks]] for additional information on configuring suspend/hibernate hooks. Also see {{ic|man systemctl}}, {{ic|man systemd-sleep}}, and {{ic|man systemd.special}}.
  
 
=== pm-utils ===
 
=== pm-utils ===
Line 57: Line 56:
  
 
See main article [[pm-utils]].
 
See main article [[pm-utils]].
 
== Suspend to RAM ==
 
 
Suspend to RAM should work out of the box.
 
  
 
== Hibernation ==
 
== Hibernation ==
  
In order to use hibernation, you need to create swap partition or swap file. See [[Swap]] for details.
+
In order to use hibernation, you need to create a [[swap]] partition or file. You will need to point the kernel to your swap using the {{ic|1=resume=}} kernel parameter, which is configured via the boot loader. You will also need to [[#Configure the initramfs|configure the initramfs]]. This tells the kernel to attempt resuming from the specified swap in early userspace. These three steps are described in detail below.
  
 
=== About swap partition/file size ===
 
=== About swap partition/file size ===
Line 76: Line 71:
 
=== Required kernel parameters ===
 
=== Required kernel parameters ===
  
The kernel parameter {{ic|1=resume=<swap_partition>}} has to be used. As {{ic|<swap_partition>}} you can use either kernel name of the swap partition, i.e. {{ic|/dev/sda1}}, or the [[UUID]] of the swap partition. See [[Kernel parameters]] for more examples for various bootloaders.
+
The kernel parameter {{ic|1=resume=''swap_partition''}} has to be used. Either the name the kernel assigns to the partition or its [[UUID]] can be used as {{ic|''swap_partition''}}. For example:
  
For example, with GRUB2 you can use {{ic|GRUB_CMDLINE_LINUX}} variable:
+
* {{ic|1=resume=/dev/sda1}}
 +
* {{ic|1=resume=UUID=4209c845-f495-4c43-8a03-5363dd433153}}
 +
* {{ic|1=resume=/dev/mapper/archVolumeGroup-archLogicVolume}} -- example if using LVM
  
{{hc|/etc/default/grub|2=GRUB_CMDLINE_LINUX="resume=/dev/sda1"}}
+
Generally, the naming method used for the {{ic|resume}} parameter should be the same as used for the {{ic|root}} parameter.
  
And if you use UUID instead:
+
The configuration depends on the used [[boot loader]], refer to [[Kernel parameters]] for details.
  
{{hc|/etc/default/grub|2=GRUB_CMDLINE_LINUX="resume=UUID=4209c845-f495-4c43-8a03-5363dd433153"}}
+
==== Hibernation into swap file ====
  
Don't forget to run {{ic|grub-mkconfig -o /boot/grub/grub.cfg}} afterwards.
+
{{Warning|[[Btrfs#Swap file|Btrfs]] does not support swap files. Failure to heed this warning may result in file system corruption. While a swap file may be used on Btrfs when mounted through a loop device, this will result in severely degraded swap performance.}}
  
{{Tip|As an alternative, for GRUB2 you may try this solution from [http://wiki.debian.org/Grub#Configuring_grub_v2 debian wiki], which automatically adds your first swap partition to {{ic|1=resume=}} parameter to all found linux entries.}}
+
Using a swap file instead of a swap partition requires an additional kernel parameter {{ic|1=resume_offset=''swap_file_offset''}}.
  
==== Hibernation into swap file ====
+
The value of {{ic|''swap_file_offset''}} can be obtained by running {{ic|filefrag -v ''swap_file''}}, the output is in a table format and the required value is located in the first row of the {{ic|physical_offset}} column. For example:
 
+
Using a swap file instead of a swap partition requires an additional kernel parameter {{ic|1=resume_offset=<Swap File Offset>}}.
+
  
The value of {{ic|<Swap File Offset>}} can be obtained by running {{ic|filefrag -v <Swap File>}}, the output is in a table format and the required value is located in the first row of the {{ic|physical_offset}} column. For example:
 
 
{{hc|# filefrag -v /swapfile|<nowiki>
 
{{hc|# filefrag -v /swapfile|<nowiki>
ilesystem type is: ef53
+
Filesystem type is: ef53
 
File size of /swapfile is 4294967296 (1048576 blocks of 4096 bytes)
 
File size of /swapfile is 4294967296 (1048576 blocks of 4096 bytes)
 
  ext:    logical_offset:        physical_offset: length:  expected: flags:
 
  ext:    logical_offset:        physical_offset: length:  expected: flags:
Line 105: Line 99:
 
</nowiki>}}
 
</nowiki>}}
  
In the example the value of {{ic|<Swap File Offset>}} is {{ic|38912}}.
+
In the example the value of {{ic|''swap_file_offset''}} is {{ic|38912}}.
  
{{Tip|The value of {{ic|<Swap File Offset>}} can also be obtained by running {{ic|swap-offset <Swap File>}}. The ''swap-offset'' binary is provided by package {{AUR|uswsusp-git}}.}}
+
The value of {{ic|''swap_file_offset''}} can also be obtained by running {{ic|swap-offset ''swap_file''}}. The ''swap-offset'' binary is provided by package {{AUR|uswsusp-git}}.
  
 
{{Note|
 
{{Note|
* Please note that in the kernel parameter {{ic|resume}} you have to provide the device of the partition that contains the swapfile, not swapfile itself! The parameter {{ic|resume_offset}} informs the system where the swapfile starts on the resume device.
+
* The {{ic|resume}} kernel parameter specifies the device of the partition that contains the swap file, not swap file itself! The parameter {{ic|resume_offset}} informs the system where the swap file starts on the resume device. Before the first hibernation a reboot is required for them to be active.
* If using [[uswsusp]], then these two parameters have to be provided in {{ic|/etc/suspend.conf}} via the keys {{ic|resume device}} and {{ic|resume offset}}.
+
* If using [[uswsusp]], then these two parameters have to be provided in {{ic|/etc/suspend.conf}} via the keys {{ic|resume device}} and {{ic|resume offset}}. No reboot is required in this case.}}
}}
+
  
=== Recreate initial ramdisk ===
+
{{Tip|You might want to decrease the [[Swap#Swappiness]] for your swapfile if the only purpose is to be able to hibernate and not expand RAM.}}
  
If you use an initramfs (default Arch systems do), you must add the {{ic|resume}} hook into the HOOKS in the configuration of [[mkinitcpio]]:
+
=== Configure the initramfs ===
  
{{hc|/etc/mkinitcpio.conf|2=
+
* When an [[initramfs]] with the {{ic|base}} hook is used, which is the default, the {{ic|resume}} hook is required in {{ic|/etc/mkinitcpio.conf}}. Whether by label or by UUID, the swap partition is referred to with a udev device node, so the {{ic|resume}} hook must go ''after'' the {{ic|udev}} hook. This example was made starting from the default hook configuration:
# resume must be placed after block and lvm2, but before filesystems
+
HOOKS="... block lvm2 '''resume''' filesystems ..."
+
}}
+
  
Finally, you must rebuild the initrd image for these changes to take effect:
+
:{{bc|1=HOOKS="base udev '''resume''' autodetect modconf block filesystems keyboard fsck"}}
  
# mkinitcpio -p linux
+
:Remember to [[Mkinitcpio#Image creation and activation|rebuild the initramfs]] for these changes to take effect.
  
{{Note|If you use a custom kernel, then you might have to change the value of the {{ic|-p}} option.}}
+
:{{Note|[[LVM]] users should add the {{ic|resume}} hook after {{ic|lvm2}}.}}
 +
 
 +
* When an initramfs with the {{ic|systemd}} hook is used, a resume mechanism is already provided, and no further hooks need to be added.
  
 
== Troubleshooting ==
 
== Troubleshooting ==
Line 134: Line 126:
  
 
You might want to tweak your '''DSDT table''' to make it work. See [[DSDT]] article
 
You might want to tweak your '''DSDT table''' to make it work. See [[DSDT]] article
 +
 +
=== VAIO Users ===
 +
 +
Add acpi_sleep=nonvs kernel flag to your loader, and you are done!
 +
 +
=== Suspend/hibernate doesn't work, or not consistently ===
 +
 +
There have been many reports about the screen going black without easily viewable errors or the ability to do anything when going into and coming back from suspend and/or hibernate. These problems have been seen on both laptops and desktops. This is not an official solution, but switching to an older kernel, especially the LTS-kernel, will probably fix this.
 +
 +
Sometimes the screen goes black due to device initialization from within the initramfs. Removing any modules you might have in [[Mkinitcpio#MODULES]] and rebuilding the initramfs, can possibly solve this issue, specially graphics drivers for [[Kernel_mode_setting#Early_KMS_start|early KMS]]. Initializing such devices before resuming can cause inconsistencies that prevents the system resuming from hibernation. This does not affect resuming from RAM. Also, check this [https://01.org/blogs/rzhang/2015/best-practice-debug-linux-suspend/hibernate-issues article] for the best practices to debug suspend/hibernate issues.
 +
 +
=== Wake-on-LAN ===
 +
 +
If [[Wake-on-LAN]] is active, the network interface card will consume power even if the computer is hibernated.
 +
 +
=== Instantaneous wakeups from suspend ===
 +
 +
For some Intel Haswell systems with the LynxPoint and LynxPoint-LP chipset, instantaneous wakeups after suspend are reported. They are linked to erroneous BIOS ACPI implementations and how the {{ic|xhci_hcd}} module interprets it during boot. As a work-around reported affected systems are added to a blacklist (named {{ic|XHCI_SPURIOUS_WAKEUP}}) by the kernel case-by-case.[https://bugzilla.kernel.org/show_bug.cgi?id=66171#c6]
 +
 +
Instantaneous resume may happen, for example, if a USB device is plugged during suspend and ACPI wakeup triggers are enabled. A viable work-around for such a system, if it is not on the blacklist yet, is to disable the wakeup triggers. An example to disable wakeup through USB is described as follows.[https://bbs.archlinux.org/viewtopic.php?pid=1575617]
 +
 +
To view the current configuration:
 +
 +
{{hc|$ cat /proc/acpi/wakeup|
 +
Device  S-state  Status  Sysfs node
 +
...
 +
EHC1      S3    *enabled  pci:0000:00:1d.0
 +
EHC2      S3    *enabled  pci:0000:00:1a.0
 +
XHC      S3    *enabled  pci:0000:00:14.0
 +
...
 +
}}
 +
 +
The relevant devices are {{ic|EHC1}}, {{ic|EHC1}} and {{ic|XHC}} (for USB 3.0). To toggle their state you have to echo the device name to the file as root.
 +
 +
# echo EHC1 > /proc/acpi/wakeup
 +
# echo EHC2 > /proc/acpi/wakeup
 +
# echo XHC > /proc/acpi/wakeup
 +
 +
This should result in suspension working again. However, this settings are only temporary and would have to be set at every reboot. To automate this take a look at [[systemd#Writing unit files]]. See [https://bbs.archlinux.org/viewtopic.php?pid=1575617#p1575617 BBS thread] for a possible solution and more information.

Latest revision as of 17:47, 11 August 2016

Currently there are three methods of suspending available: suspend to RAM (usually called just suspend), suspend to disk (usually known as hibernate), and hybrid suspend (sometimes aptly called suspend to both):

  • Suspend to RAM method cuts power to most parts of the machine aside from the RAM, which is required to restore the machine's state. Because of the large power savings, it is advisable for laptops to automatically enter this mode when the computer is running on batteries and the lid is closed (or the user is inactive for some time).
  • Suspend to disk method saves the machine's state into swap space and completely powers off the machine. When the machine is powered on, the state is restored. Until then, there is zero power consumption.
  • Suspend to both method saves the machine's state into swap space, but does not power off the machine. Instead, it invokes usual suspend to RAM. Therefore, if the battery is not depleted, the system can resume from RAM. If the battery is depleted, the system can be resumed from disk, which is much slower than resuming from RAM, but the machine's state has not been lost.

There are multiple low level interfaces (backends) providing basic functionality, and some high level interfaces providing tweaks to handle problematic hardware drivers/kernel modules (e.g. video card re-initialization).

Low level interfaces

Though these interfaces can be used directly, it is advisable to use some of high level interfaces to suspend/hibernate. Using low level interfaces directly is significantly faster than using any high level interface, since running all the pre- and post-suspend hooks takes time, but hooks can properly set hardware clock, restore wireless etc.

kernel (swsusp)

The most straightforward approach is to directly inform the in-kernel software suspend code (swsusp) to enter a suspended state; the exact method and state depends on the level of hardware support. On modern kernels, writing appropriate strings to /sys/power/state is the primary mechanism to trigger this suspend.

See kernel documentation for details.

uswsusp

The uswsusp ('Userspace Software Suspend') is a wrapper around the kernel's suspend-to-RAM mechanism, which performs some graphics adapter manipulations from userspace before suspending and after resuming.

See main article Uswsusp.

tuxonice

TuxOnIce is a fork of the kernel implementation of suspend/hibernate that provides kernel patches to improve the default implementation. It requires a custom kernel to achieve this purpose.

See main article TuxOnIce.

High level interfaces

Note: The end goal of these packages is to provide binaries/scripts that can be invoked to perform suspend/hibernate. Actually hooking them up to power buttons or menu clicks or laptop lid events is usually left to other tools. To automatically suspend/hibernate on certain power events, such as laptop lid close or battery depletion percentage, you may want to look into running Acpid.

systemd

systemd provides native commands for suspend, hibernate and a hybrid suspend, see Power management#Power management with systemd for details. This is the default interface used in Arch Linux.

See Power management#Sleep hooks for additional information on configuring suspend/hibernate hooks. Also see man systemctl, man systemd-sleep, and man systemd.special.

pm-utils

pm-utils is a set of shell scripts that encapsulate the backend's suspend/hibernate functionality. It comes with a set of pre- and post-suspend tweaks and various hooks to customize the process.

See main article pm-utils.

Hibernation

In order to use hibernation, you need to create a swap partition or file. You will need to point the kernel to your swap using the resume= kernel parameter, which is configured via the boot loader. You will also need to configure the initramfs. This tells the kernel to attempt resuming from the specified swap in early userspace. These three steps are described in detail below.

About swap partition/file size

Even if your swap partition is smaller than RAM, you still have a big chance of hibernating successfully. According to kernel documentation:

/sys/power/image_size controls the size of the image created by the suspend-to-disk mechanism. It can be written a string representing a non-negative integer that will be used as an upper limit of the image size, in bytes. The suspend-to-disk mechanism will do its best to ensure the image size will not exceed that number. However, if this turns out to be impossible, it will try to suspend anyway using the smallest image possible. In particular, if "0" is written to this file, the suspend image will be as small as possible. Reading from this file will display the current image size limit, which is set to 2/5 of available RAM by default.

You may either decrease the value of /sys/power/image_size to make the suspend image as small as possible (for small swap partitions), or increase it to possibly speed up the hibernation process.

Required kernel parameters

The kernel parameter resume=swap_partition has to be used. Either the name the kernel assigns to the partition or its UUID can be used as swap_partition. For example:

  • resume=/dev/sda1
  • resume=UUID=4209c845-f495-4c43-8a03-5363dd433153
  • resume=/dev/mapper/archVolumeGroup-archLogicVolume -- example if using LVM

Generally, the naming method used for the resume parameter should be the same as used for the root parameter.

The configuration depends on the used boot loader, refer to Kernel parameters for details.

Hibernation into swap file

Warning: Btrfs does not support swap files. Failure to heed this warning may result in file system corruption. While a swap file may be used on Btrfs when mounted through a loop device, this will result in severely degraded swap performance.

Using a swap file instead of a swap partition requires an additional kernel parameter resume_offset=swap_file_offset.

The value of swap_file_offset can be obtained by running filefrag -v swap_file, the output is in a table format and the required value is located in the first row of the physical_offset column. For example:

# filefrag -v /swapfile
Filesystem type is: ef53
File size of /swapfile is 4294967296 (1048576 blocks of 4096 bytes)
 ext:     logical_offset:        physical_offset: length:   expected: flags:
   0:        0..       0:      38912..     38912:      1:            
   1:        1..   22527:      38913..     61439:  22527:             unwritten
   2:    22528..   53247:     899072..    929791:  30720:      61440: unwritten
...

In the example the value of swap_file_offset is 38912.

The value of swap_file_offset can also be obtained by running swap-offset swap_file. The swap-offset binary is provided by package uswsusp-gitAUR.

Note:
  • The resume kernel parameter specifies the device of the partition that contains the swap file, not swap file itself! The parameter resume_offset informs the system where the swap file starts on the resume device. Before the first hibernation a reboot is required for them to be active.
  • If using uswsusp, then these two parameters have to be provided in /etc/suspend.conf via the keys resume device and resume offset. No reboot is required in this case.
Tip: You might want to decrease the Swap#Swappiness for your swapfile if the only purpose is to be able to hibernate and not expand RAM.

Configure the initramfs

  • When an initramfs with the base hook is used, which is the default, the resume hook is required in /etc/mkinitcpio.conf. Whether by label or by UUID, the swap partition is referred to with a udev device node, so the resume hook must go after the udev hook. This example was made starting from the default hook configuration:
HOOKS="base udev resume autodetect modconf block filesystems keyboard fsck"
Remember to rebuild the initramfs for these changes to take effect.
Note: LVM users should add the resume hook after lvm2.
  • When an initramfs with the systemd hook is used, a resume mechanism is already provided, and no further hooks need to be added.

Troubleshooting

ACPI_OS_NAME

You might want to tweak your DSDT table to make it work. See DSDT article

VAIO Users

Add acpi_sleep=nonvs kernel flag to your loader, and you are done!

Suspend/hibernate doesn't work, or not consistently

There have been many reports about the screen going black without easily viewable errors or the ability to do anything when going into and coming back from suspend and/or hibernate. These problems have been seen on both laptops and desktops. This is not an official solution, but switching to an older kernel, especially the LTS-kernel, will probably fix this.

Sometimes the screen goes black due to device initialization from within the initramfs. Removing any modules you might have in Mkinitcpio#MODULES and rebuilding the initramfs, can possibly solve this issue, specially graphics drivers for early KMS. Initializing such devices before resuming can cause inconsistencies that prevents the system resuming from hibernation. This does not affect resuming from RAM. Also, check this article for the best practices to debug suspend/hibernate issues.

Wake-on-LAN

If Wake-on-LAN is active, the network interface card will consume power even if the computer is hibernated.

Instantaneous wakeups from suspend

For some Intel Haswell systems with the LynxPoint and LynxPoint-LP chipset, instantaneous wakeups after suspend are reported. They are linked to erroneous BIOS ACPI implementations and how the xhci_hcd module interprets it during boot. As a work-around reported affected systems are added to a blacklist (named XHCI_SPURIOUS_WAKEUP) by the kernel case-by-case.[1]

Instantaneous resume may happen, for example, if a USB device is plugged during suspend and ACPI wakeup triggers are enabled. A viable work-around for such a system, if it is not on the blacklist yet, is to disable the wakeup triggers. An example to disable wakeup through USB is described as follows.[2]

To view the current configuration:

$ cat /proc/acpi/wakeup
Device  S-state   Status   Sysfs node
...
EHC1      S3    *enabled  pci:0000:00:1d.0
EHC2      S3    *enabled  pci:0000:00:1a.0
XHC       S3    *enabled  pci:0000:00:14.0
...

The relevant devices are EHC1, EHC1 and XHC (for USB 3.0). To toggle their state you have to echo the device name to the file as root.

# echo EHC1 > /proc/acpi/wakeup
# echo EHC2 > /proc/acpi/wakeup
# echo XHC > /proc/acpi/wakeup

This should result in suspension working again. However, this settings are only temporary and would have to be set at every reboot. To automate this take a look at systemd#Writing unit files. See BBS thread for a possible solution and more information.