Updated power savings settings for Samsung Series 9 (NP900X3C-A05UK) and Ubuntu 14.10

Here is my updated /etc/rc.local for Ubuntu 14.10

#!/bin/sh -e

# Sleep so all services have started before we change settings
sleep 5

# Set Intel Audio to power save 
echo '1' > '/sys/module/snd_hda_intel/parameters/power_save';

# Temp disable ethernet port
modprobe -r r8169

# Wireless Power Saving for interface wlan0
iw dev wlan0 set power_save on

# VM writeback timeout
echo '1500' > '/proc/sys/vm/dirty_writeback_centisecs';

# Temp disable bluetooth
modprobe -r btusb

# Adjust backlight to start much lower
echo 800 > '/sys/class/backlight/intel_backlight/brightness'

# - NMI Watchdog (turned off)
echo 0 > '/proc/sys/kernel/nmi_watchdog';

# - SATA Active Link Power management
for i in `find /sys/class/scsi_host/*/link_power_management_policy`; do echo 'min_power' > $i; done;

# - USB Autosuspend (after 2 secs of inactivity)
for i in `find /sys/bus/usb/devices/*/power/control`; do echo auto > $i; done;
for i in `find /sys/bus/usb/devices/*/power/autosuspend`; do echo 2 > $i; done;

# - Device Power Management
echo 'auto' | tee /sys/bus/i2c/devices/*/power/control > /dev/null;
echo 'auto' | tee /sys/bus/pci/devices/*/power/control > /dev/null;

# - CPU Scaling (power saving scaling governor for all CPU's
for i in `find /sys/devices/system/cpu/*/cpufreq/scaling_governor`; do echo 'powersave' > $i; done;

exit 0

5 thoughts on “Updated power savings settings for Samsung Series 9 (NP900X3C-A05UK) and Ubuntu 14.10”

  1. Steve you might need to adjust the sleep value (5) to be higher or move it into a user profile setting as when you login it can reset the brightness value.

    Also check the correct path under sys:

    /sys/class/backlight/intel_backlight/brightness

    As I noticed with different versions of Ubuntu and/or models of the laptop the path is slightly different

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