Atom Z500 Series:Reducing power consumption

I own a Packard bell netbook dot_m.nl/200.

Hardware

It has the following specs:

- Intel Atom Z520 (1.33GHz) cpu
- 1GB DDR2-800 memory

I have replaced the hard drive with a Kingston SNVP325S2128GB SSD.

# lspci
00:00.0 Host bridge: Intel Corporation System Controller Hub (SCH Poulsbo) (rev 07)
00:02.0 VGA compatible controller: Intel Corporation System Controller Hub (SCH Poulsbo) Graphics Controller (rev 07)
00:1b.0 Audio device: Intel Corporation System Controller Hub (SCH Poulsbo) HD Audio Controller (rev 07)
00:1c.0 PCI bridge: Intel Corporation System Controller Hub (SCH Poulsbo) PCI Express Port 1 (rev 07)
00:1c.1 PCI bridge: Intel Corporation System Controller Hub (SCH Poulsbo) PCI Express Port 2 (rev 07)
00:1d.0 USB Controller: Intel Corporation System Controller Hub (SCH Poulsbo) USB UHCI #1 (rev 07)
00:1d.1 USB Controller: Intel Corporation System Controller Hub (SCH Poulsbo) USB UHCI #2 (rev 07)
00:1d.2 USB Controller: Intel Corporation System Controller Hub (SCH Poulsbo) USB UHCI #3 (rev 07)
00:1d.7 USB Controller: Intel Corporation System Controller Hub (SCH Poulsbo) USB EHCI #1 (rev 07)
00:1f.0 ISA bridge: Intel Corporation System Controller Hub (SCH Poulsbo) LPC Bridge (rev 07)
00:1f.1 IDE interface: Intel Corporation System Controller Hub (SCH Poulsbo) IDE Controller (rev 07)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 02)
03:00.0 Ethernet controller: Atheros Communications Inc. AR5001 Wireless Network Adapter (rev 01)
# lsusb
Bus 001 Device 002: ID 04f2:b175 Chicony Electronics Co., Ltd 4-Port Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Powertop has helped me greatly in finding ways to reduce power consumption.

For now I have the following in my startup:

startup script

# turn the wireless transmit power down to 1 mW
iwconfig wlan0 txpower 0

# put the cpu frequency governor "conservative" in charge
echo "conservative" >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo "conservative" >/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

# turn down the backlight brightness to somewhat visible
echo 6 >/sys/class/backlight/psb-bl/brightness

# delay dirty writeback to 15 seconds
echo 1500 >/proc/sys/vm/dirty_writeback_centisecs
# turn wake up on lan off, so it's really off when it's off
ethtool -s eth0 wol d
# autosuspend auto (2 sec) for integrated usb hub
echo 2 >/sys/bus/usb/devices/1-4/power/autosuspend
echo auto >/sys/bus/usb/devices/1-4/power/level
# autosuspend on all pci devices
for x in /sys/bus/pci/devices/*/power/control; do echo auto >$x ; done

# let kernel handle fan control (does this work?)
echo enabled >/sys/class/thermal/thermal_zone0/mode

Also

You can not use

# turn down the power consumption on the intel SCH ata
echo min_power >/sys/class/scsi_host/host0/link_power_management_policy
# wlan power timeout to 500ms
iwconfig wlan0 power timeout 500ms

You should disable the acer_wmi driver, for it interferes with normal backlight operations and does not add anything on this laptop.

Also see:

- http://www.thinkwiki.org/wiki/How_to_reduce_power_consumption
- https://01.org/powertop/
- http://piie.net/files/acerhdf_README.txt