sleep: store battery discharge rate/hour with hash

Estimated battery discharge rate per hour is stored in :
/var/lib/systemd/sleep/battery_discharge_percentage_rate_per_hour

This value is used to determine the initial suspend interval. In case
this file is not available or value is invalid, HibernateDelaySec
interval is used.
After wakeup from initial suspend, this value is again estimated and
written to file if value is in range of 1-199.

Logs for reference : HibernateDelaySec=15min
- Updated in /etc/systemd/sleep.conf

Jul 14 19:17:58 localhost systemd-sleep[567]: Current battery charge
percentage: 100%
Jul 14 19:17:58 localhost systemd-sleep[567]: Failed to read discharge
rate from /var/lib/systemd/sleep/batt
ery_discharge_percentage_rate_per_hour: No such file or directory
Jul 14 19:17:58 localhost systemd-sleep[567]: Set timerfd wake alarm
for 15min
Jul 14 19:33:00 localhost systemd-sleep[567]: Current battery charge
percentage after wakeup: 90%
Jul 14 19:33:00 localhost systemd-sleep[567]: Attempting to estimate
battery discharge rate after wakeup from 15min sleep
Jul 14 19:33:00 localhost systemd-sleep[567]: product_id does not
exist: No such file or directory
Jul 14 19:33:00 localhost systemd-sleep[567]: Estimated discharge rate
39 successfully updated to
/var/lib/systemd/sleep/battery_discharge_percentage_rate_per_hour
Jul 14 19:33:00 localhost systemd-sleep[567]: Current battery charge
percentage: 90%
Jul 14 19:33:00 localhost systemd-sleep[567]: product_id does not
exist: No such file or directory
Jul 14 19:33:00 localhost systemd-sleep[567]: Set timerfd wake alarm
for 1h 48min 27s
Jul 14 21:21:30 localhost systemd-sleep[567]: Current battery charge
percentage after wakeup: 90%
Jul 14 21:21:30 localhost systemd-sleep[567]: Battery was not
discharged during suspension

1 files changed, 17 insertions, 6 deletions

diff --git a/man/systemd-sleep.conf.xml b/man/systemd-sleep.conf.xml
index 0c01ecf3ff..2f04ce84a1 100644
--- a/man/systemd-sleep.conf.xml
+++ b/man/systemd-sleep.conf.xml
@@ -78,9 +78,20 @@
         <term>suspend-then-hibernate</term>
 
         <listitem><para>A low power state where the system is initially suspended
-        (the state is stored in RAM). If not interrupted within the delay specified by
-        <command>HibernateDelaySec=</command>, the system will be woken using an RTC
-        alarm and hibernated (the state is then stored on disk).
+        (the state is stored in RAM) and then hibernated based on battery percentage
+        capacity. If the current battery capacity is higher than 5%, the system goes
+        back to suspend for interval calculated using battery disharge rate per hour.
+        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 a timespan. In case of manual wakeup before RTC alarm, the timespan
+        is the duration for which system was suspended. If the file does not exist or
+        has invalid value, initial suspend duration is set to
+        <command>HibernateDelaySec=</command>.
+        After wakeup via an RTC alarm, the 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 amount of time it would take to fully
+        discharge the battery minus 30 minutes.
         </para></listitem>
       </varlistentry>
 
@@ -173,9 +184,9 @@
       </varlistentry>
       <varlistentry>
         <term><varname>HibernateDelaySec=</varname></term>
-
-        <listitem><para>The amount of time the system spends in suspend mode before the system is
-        automatically put into hibernate mode, when using
+        <listitem><para>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.
         <citerefentry><refentrytitle>systemd-suspend-then-hibernate.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. Defaults
         to 2h.</para></listitem>
       </varlistentry>