Power management/Suspend and hibernate
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Manually suspending the operating system, either to memory (standby) or to disk (hibernate) sometimes provides the most efficient way to optimize battery life, depending on the usage pattern of the laptop. While there is relatively straightforward support in the linux kernel to support these operations, typically some adjustments have to made before initiating these operations (typically due to problematic drivers, modules or hardware). The following tools provide wrappers around the kernel interfaces to suspend/resume
- Wrappers: Systemd, pm-utils
- Backend: kernel, uswsusp, tuxonice
It needs a swap partiton.
About swap partition size
Even if your swap partition is smaller than RAM, you still have a big chance in hibernating successfully. According to kernel documentation: "
/sys/power/image_size controls the size of the image created by the suspend-to-disk mechanism [...] which is set to 2/5 of available RAM by default. [...] The suspend-to-disk mechanism will do its best to ensure the image size will not exceed that number." You may either decrease it due to a small swap partition or increase it in purpose of possible hibernation speed up.
Add Kernel Parameters
resume=SWAP_PARTITION has to be passed to the Kernel parameters (where
SWAP_PARTITION is either your swap device, i.e.
/dev/sdaX, or your swap UUID). Consult Kernel parameters for more info.
kernel /boot/vmlinuz-linux ... resume=/dev/sdaX
If you are using swap file instead of regular swap partition. Consule Swap#Swap file resuming for more info.
kernel /boot/vmlinuz-linux ... resume=/dev/sdaX resume_offset=12345
Add Resume Hook
# resume must be placed after ide scsi sata and/or lvm2, but before filesystems HOOKS="... ide scsi sata lvm2 resume filesystems"
You must rebuild the initrd image for these changes to take effect:
# mkinitcpio -p linux
uswsusp (userspace software suspend) is a set of user space tools used for hibernation (suspend-to-disk) and suspend (suspend-to-RAM or standby) on Linux systems.
TuxOnIce , an advanced suspend/hibernate framework which supports suspending to a swap-disk or a regular file with fast LZO-compression.
Systemd handles some power-related ACPI events.
# systemctl suspend # systemctl hibernate
pm-utils is a suspend and powerstate setting framework.
# pm-suspend # pm-hibernate