[ltp] X60 power consumption

[Nils Faerber]

Richard Neill schrieb:
> Dear X60 users,
Hi fellow!

> I recall some people mentioning power-consumptions in the region of 6-8W
> for an X60. I'm getting 11W, even after following all the
> power-reduction instructions on thinkwiki (inc. min backlight). Does
> anyone have any particular tips?  What battery life would you expect
> from a new 8-cell pack?

I get 5 to 6 hours (under optimal conditions).

> I've already swapped out the HDD for an SSD (does the writeback time and
> laptop-mode stuff still apply here? Does it make a difference that I'm
> using it in Compatibility mode rather than AHCI mode - as suggested by
> the manufacturer, OCZ).

Uh, dunno.

> Does having 4GB RAM hurt power-consumption?

It can, depending on the RAM chips, I guess.
Because of the very high speed of DDR2 RAM nowadays the quality of the
chips can make a huge difference. There is special "mobile DDR2 RAM"
which saves quite an amount of power.

> Does turning the wireless power down hurt range, or just throughput?
> (the AP is not very close)

I *think* only throughput. But the documentation about the powersave
modes is pretty small (or close to none, just which values are valid). I
usuall use the battery mode (7) and did not notice anything bad yet.

> Also, it's hard to know which of the tips make a big difference, and
> which don't. For example, does suspending the soundcard save a few mW,
> or a substantial power? If I have bluetooth already switched off with
> Fn-F5, is it really off?

Well, any mW you can save is good especially if the sound subsystem does
it automatically for you.
Concerning Bluetooth this can be a real hog!
For what reason ever Lenovo (perhaps spilling another ton of dimes onto
their bank accounts) used a USB-1 connected Bluetooth-2.0 chipset which
means as soon as you have Bluetooth active it will cause the CPU to be
much more active - almost never reaches C4 anymore. So yes, turning off
Bluetooth helps. If the LED is off and "hciconfig" does not show a
device it is pretty surely off.

> One of the powertop suggestions causes the system to emit a faint
> buzzing when I move the mouse pointer!

Which one was that?
The slight hissing and buzzing noises are caused by the switching power
regulators inside the machine. Depending on the quality of the MOS-FETs
and coils used they can emit low noise. Nothing to worry about except
for being annoying (and again using higher quality parts could avoid that).

For me the following does most of what I think is good for saving power:

echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
hdparm -B 254 /dev/sda > /dev/null
ifconfig eth1 up
echo 7 > /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/power_level
echo 5 > /proc/sys/vm/laptop_mode
ethtool -s eth0 wol d
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
echo "auto" > `hal-get-property --udi \
/org/freedesktop/Hal/devices/usb_device_483_2016_noserial --key \
linux.sysfs_path`/power/level
echo min_power > /sys/class/scsi_host/host0/link_power_management_policy
echo shutdown > /sys/power/disk

Using this I can get about 9 to 9.5W with WiFi enabled which is IMHO OK.
(And no need to unload the uhci-hcd module...)

It is still way too much and the fan still spins almost all the time but
a lot of the power now goes into the chipset and graphics and there is
little we can do there - at least from what I know.

If you have it installed watch the powertop output and see if your CPU
stays in C4 most of the time. If not, find the course.

> Thanks,
> Richard
Cheers
  nils faerber

-- 
kernel concepts GbR        Tel: +49-271-771091-12
Sieghuetter Hauptweg 48    Fax: +49-271-771091-19
D-57072 Siegen             Mob: +49-176-21024535
http://www.kernelconcepts.de