systemd-sleep.conf, sleep.conf.d — Suspend and hibernation configuration file
/etc/systemd/sleep.conf
/etc/systemd/sleep.conf.d/*.conf
/run/systemd/sleep.conf.d/*.conf
/usr/lib/systemd/sleep.conf.d/*.conf
systemd supports four general power-saving modes:
a low-power state where execution of the OS is paused, and complete power loss might result in lost data, and which is fast to enter and exit. This corresponds to suspend, standby, or freeze states as understood by the kernel.
a low-power state where execution of the OS is paused, and complete power loss does not result in lost data, and which might be slow to enter and exit. This corresponds to the hibernation as understood by the kernel.
a low-power state where execution of the OS is paused, which might be slow to enter, and on complete power loss does not result in lost data but might be slower to exit in that case. This mode is called suspend-to-both by the kernel.
A low power state where initially user.slice unit is freezed. If the hardware supports low-battery alarms (ACPI _BTP), then the system is first suspended (the state is stored in RAM) and then hibernates if the system is woken up by the hardware via ACPI low-battery signal. Unit user.slice is thawed when system returns from hibernation. If the hardware does not support low-battery alarms (ACPI _BTP), then the system is suspended based on battery's current percentage capacity. If the current battery capacity is higher than 5%, the system suspends for interval calculated using battery discharge rate per hour or HibernateDelaySec= if former is not available. Battery discharge rate per hour is stored in a file which is created after initial suspend-resume cycle. The value is calculated using battery decreasing charge level over a timespan for which system was suspended. For each battery connected to the system, there is a unique entry. After RTC alarm wakeup from suspend, battery discharge rate per hour is again estimated. If the current battery charge level is equal to or less than 5%, the system will be hibernated (the state is then stored on disk) else the system goes back to suspend for the interval calculated using battery discharge rate per hour. In case of manual wakeup, if the battery was discharged while the system was suspended, the battery discharge rate is estimated and stored on the filesystem. In case the system is woken up by the hardware via the ACPI low-battery signal, then it hibernates.
Settings in these files determine what strings
will be written to
/sys/power/disk and
/sys/power/state by
systemd-sleep(8)
when
systemd(1)
attempts to suspend or hibernate the machine.
See
systemd.syntax(7)
for a general description of the syntax.
The default configuration is set during compilation, so configuration is only needed when it is
necessary to deviate from those defaults. Initially, the main configuration file in
/etc/systemd/ contains commented out entries showing the defaults as a guide to the
administrator. Local overrides can be created by editing this file or by creating drop-ins, as described
below. Using drop-ins for local configuration is recommended over modifications to the main configuration
file.
In addition to the "main" configuration file, drop-in configuration snippets are read from
/usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/,
and /etc/systemd/*.conf.d/. Those drop-ins have higher precedence and override the
main configuration file. Files in the *.conf.d/ configuration subdirectories are
sorted by their filename in lexicographic order, regardless of in which of the subdirectories they
reside. When multiple files specify the same option, for options which accept just a single value, the
entry in the file sorted last takes precedence, and for options which accept a list of values, entries
are collected as they occur in the sorted files.
When packages need to customize the configuration, they can install drop-ins under
/usr/. Files in /etc/ are reserved for the local administrator,
who may use this logic to override the configuration files installed by vendor packages. Drop-ins have to
be used to override package drop-ins, since the main configuration file has lower precedence. It is
recommended to prefix all filenames in those subdirectories with a two-digit number and a dash, to
simplify the ordering of the files.
To disable a configuration file supplied by the vendor, the recommended way is to place a symlink
to /dev/null in the configuration directory in /etc/, with the
same filename as the vendor configuration file.
The following options can be configured in the
[Sleep] section of
/etc/systemd/sleep.conf or a
sleep.conf.d file:
AllowSuspend=, AllowHibernation=, AllowSuspendThenHibernate=, AllowHybridSleep=¶By default any power-saving mode is advertised if possible (i.e. the kernel supports that mode, the necessary resources are available). Those switches can be used to disable specific modes.
If AllowHibernation=no or AllowSuspend=no is
used, this implies AllowSuspendThenHibernate=no and
AllowHybridSleep=no, since those methods use both suspend and hibernation
internally. AllowSuspendThenHibernate=yes and
AllowHybridSleep=yes can be used to override and enable those specific
modes.
SuspendMode=, HibernateMode=, HybridSleepMode=¶The string to be written to
/sys/power/disk by,
respectively,
systemd-suspend.service(8),
systemd-hibernate.service(8), or
systemd-hybrid-sleep.service(8).
More than one value can be specified by separating
multiple values with whitespace. They will be tried
in turn, until one is written without error. If
neither succeeds, the operation will be aborted.
systemd-suspend-then-hibernate.service(8)
uses the value of SuspendMode= when suspending and the value of HibernateMode= when hibernating.
SuspendState=, HibernateState=, HybridSleepState=¶The string to be written to
/sys/power/state by,
respectively,
systemd-suspend.service(8),
systemd-hibernate.service(8), or
systemd-hybrid-sleep.service(8).
More than one value can be specified by separating
multiple values with whitespace. They will be tried
in turn, until one is written without error. If
neither succeeds, the operation will be aborted.
systemd-suspend-then-hibernate.service(8)
uses the value of SuspendState= when suspending and the value of HibernateState= when hibernating.
HibernateDelaySec=¶The amount of time the system spends in suspend mode before the RTC alarm wakes the system, before the battery discharge rate can be estimated and used instead to calculate the suspension interval. systemd-suspend-then-hibernate.service(8). Defaults to 2h.
Example: to exploit the “freeze” mode added in Linux 3.9, one can use systemctl suspend with
[Sleep] SuspendState=freeze