Arch Linux

hack.augusto

Member

From: Brazil

Registered: 2008-08-28

Posts: 124

Power Saving - Can't reach C2

I'm trying to maximize my battery life time, I reduced the use from 30W to about 22W with this:

cpufreq-set -g ondemand
mount -o remount,relatime /
mount -o remount,relatime /mnt/files
hdparm -B 1 -S 12 /dev/sda
echo 3000 > /proc/sys/vm/dirty_writeback_centisecs
echo 5 > /proc/sys/vm/laptop_mode
echo 1 > /sys/module/snd_hda_intel/parameters/power_save
echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

but I'm unable to get my cpu to sleep at C2 or C3:

Ideas?

augustob

Member

From: Florianópolis, Brazil

Registered: 2006-03-17

Posts: 135

Re: Power Saving - Can't reach C2

Hm, are you using the stock kernel? I may be pulling stuff out of my ass here but maybe your processor needs specific options to be set. Also, check if the same thing happens when nothing is plugged to the USB ports and the networks are down (unload any wireless modules).

Also, 22W is still pretty high, I believe. My MacBook, using the performance governor, downloading stuff from a wireless network pulls about 18W. Solving the CPU state issue should drop your energy consumption even further.

PS: Another Brazilian Augusto in the Arch boards? Let's start a club or something.

hack.augusto

Member

From: Brazil

Registered: 2008-08-28

Posts: 124

Re: Power Saving - Can't reach C2

I have two kernels in my computer rigth now, the standard arch kernel and today I compiled the zen kernel, in both cases i don't get the cpu to sleep in C2, my zen kernel is compiled for my cpu family, I should try reduce the timer frequency next time. I didn't have anything sticked to my usb ports, and my wireless card is turned off.

Does anyone use the lesswatts.org patches, does it help?

PS: err, I live in florianopolis too ... that was unexpected