Arch Linux

davidbe

Member

From: Belgium

Registered: 2009-09-08

Posts: 22

Relative high power usage

Hi,

Out of curiosity I installed Linux Sabayon (Xfce-edition) on another partition on my Asus K52J laptop. Quite immidiatly I noticed a much longer battery life with Sabayon. Powertop gave me these figures:

out-of-the-box Sabayon: between 13 and 18 W
Arch with laptop-mode, openbox and these daemons running (syslog-ng dbus acpid laptop-mode cpupower crond wicd): between 20 and 30W

Frustrating! How can I investigate what causes this difference? Any starting points?

Thanks in advance,
david

/dev/zero

Member

From: Melbourne, Australia

Registered: 2011-10-20

Posts: 1,247

Re: Relative high power usage

My powertop currently tells me my laptop is running on 0.7W. I recall there's a bug that requires multiplication by 10, so make that 7W.

You just need to follow all the steps in the laptop section of the wiki. Depending on your video card, it can also make a difference to pass experimental flags to the kernel.

For your reference, I have:

• grep "^MODULES\|^DAEMONS" /etc/rc.conf

  MODULES=(ahci wl acpi_cpufreq)
  DAEMONS=(hwclock syslog-ng acpid laptop-mode dbus iptables @crond @battery_monitor @slim network @wicd @netfs @sshd)

• grep -i "grub_cmdline_linux=" /etc/default/grub

  GRUB_CMDLINE_LINUX="cryptdevice=/dev/mapper/vg-crypt:root rootfstype=ext4 pcie_aspm=force acpi_osi=Linux acpi_backlight=vendor i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1"

davidbe

Member

From: Belgium

Registered: 2009-09-08

Posts: 22

Re: Relative high power usage

I went through that page, tried several things, but that doesn't make a big difference. I even tried this script (https://bbs.archlinux.org/viewtopic.php?id=134109 top post), which puts it all together, and it gives me a gain around 5W, still not as big as switching distro...
Next to the kernel params and the settings in that script, is there something I'm missing?

Kind regards,
David

Wilco

Member

Registered: 2008-11-09

Posts: 440

Re: Relative high power usage

Did you follow all the tips powertop gives you? That should help a few watts. It could also be an app running in the background causing many wakups

davidbe

Member

From: Belgium

Registered: 2009-09-08

Posts: 22

Re: Relative high power usage

I found an explanation! Sabayon Linux (and others) offer fglrx installation. So I did a test: I created a spare partition and installed a bare Arch Linux environment. Only openbox, cpufrequtils, laptop-mode and powertop2 running with xf86-video-ati. This resulted in a battery usage between 20W and 30W.
Then, I removed xf86-video-ati and installed catalyst. The same setup resulted in a battery usage between 15W and 20W.

Is this a known issue? I guess I'm staying with catalyst for a while. It is a 20% gain... which is rather big enough to stick with catalyst. Except, when maintenance takes up too much time, I'll move back to xf86-video-ati.

sankeytm

Member

From: California

Registered: 2012-03-05

Posts: 28

Re: Relative high power usage

It's only an issue with defaults. By default xf86-video-ati locks on the highest frequency (in my experience). You need to choose a profile for your video card so it will idle at a much lower frequency. See powersaving with KMS enabled

Last edited by sankeytm (2012-03-31 05:33:44)

davidbe

Member

From: Belgium

Registered: 2009-09-08

Posts: 22

Re: Relative high power usage

You're 100% correct. I didn't check that wikipage that well.
Thanks!