CentOS - Aug 2012 - CentOS 6 : Tip for significantly increasing battery life / reducing power consumption (Thinkpad X220 Tablet)

Hello,

I was not happy with the power consumption of CentOS 6 x86_64 on a new
Lenovo Thinkpad x220 Tablet and I worked on reducing it. I just wanted
to share with the list one of the changes which gave me the most
significant improvement.

As per http://www.williambrownstreet.net/blog/?p=387, add the
following kernel arguments to the GRUB boot configuration:

pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
i915.i915_enable_fbc=1

(in /boot/efi/EFI/redhat/grub.conf since I use EFI,
/boot/grub/grub.conf otherwise)

As measured using PowerTop, this made the power consumption decrease
from 20W to 11W !
(I had already decreased it from 25W to 20W with the usual tips of
disabling hardware, shutting down services, switching tuned profiles,
etc.)

All in all, battery time was more than multiplied by two, and the
computer is now much more silent since the fan is not always running
like mad in order to cool the processor. The bottom of the laptop is
not anymore hot as hell.

I don't know whether this would have an impact on other hardware, but
it may be worth looking at it (even on servers?), since the above link
points to descriptions of a regression in the kernel which seems more
general.

As a side note, the Power Management Guide of Red Hat is a good
resource (analysis tools + tuned profiles):
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Power_Management_Guide/

Cheers,

Mathieu

PS: Do you think I should book a bug in the upstream bug tracker?

On Fri, Aug 3, 2012 at 3:05 PM, Mathieu Baudier <mbaudier at argeo.org>
wrote:
> pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
> i915.i915_enable_fbc=1
Interesting as now I'm using RHEL 6.3 on T400.
Would that make the notebook slower?

-- 
http://linux3.arinet.org

On 03/08/12 08:05, Mathieu Baudier wrote:
> Hello,
>
> I was not happy with the power consumption of CentOS 6 x86_64 on a new
> Lenovo Thinkpad x220 Tablet and I worked on reducing it. I just wanted
> to share with the list one of the changes which gave me the most
> significant improvement.
>
> As per http://www.williambrownstreet.net/blog/?p=387, add the
> following kernel arguments to the GRUB boot configuration:
>
> pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
> i915.i915_enable_fbc=1
>
> (in /boot/efi/EFI/redhat/grub.conf since I use EFI,
> /boot/grub/grub.conf otherwise)
>
> As measured using PowerTop, this made the power consumption decrease
> from 20W to 11W !
> (I had already decreased it from 25W to 20W with the usual tips of
> disabling hardware, shutting down services, switching tuned profiles,
> etc.)
>
> All in all, battery time was more than multiplied by two, and the
> computer is now much more silent since the fan is not always running
> like mad in order to cool the processor. The bottom of the laptop is
> not anymore hot as hell.
>
> I don't know whether this would have an impact on other hardware, but
> it may be worth looking at it (even on servers?), since the above link
> points to descriptions of a regression in the kernel which seems more
> general.
>
> As a side note, the Power Management Guide of Red Hat is a good
> resource (analysis tools + tuned profiles):
>
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Power_Management_Guide/
>
> Cheers,
>
> Mathieu
>
> PS: Do you think I should book a bug in the upstream bug tracker?
Rather than filing a bug upstream, I would think it more appropriate to 
document the various settings on the CentOS Wiki in the laptops section:

http://wiki.centos.org/HowTos/Laptops

----- Original Message -----
| Hello,
| 
| I was not happy with the power consumption of CentOS 6 x86_64 on a
| new
| Lenovo Thinkpad x220 Tablet and I worked on reducing it. I just
| wanted
| to share with the list one of the changes which gave me the most
| significant improvement.
| 
| As per http://www.williambrownstreet.net/blog/?p=387, add the
| following kernel arguments to the GRUB boot configuration:
| 
| pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
| i915.i915_enable_fbc=1
| 
| (in /boot/efi/EFI/redhat/grub.conf since I use EFI,
| /boot/grub/grub.conf otherwise)
| 
| As measured using PowerTop, this made the power consumption decrease
| from 20W to 11W !
| (I had already decreased it from 25W to 20W with the usual tips of
| disabling hardware, shutting down services, switching tuned profiles,
| etc.)
| 
| All in all, battery time was more than multiplied by two, and the
| computer is now much more silent since the fan is not always running
| like mad in order to cool the processor. The bottom of the laptop is
| not anymore hot as hell.
| 
| I don't know whether this would have an impact on other hardware, but
| it may be worth looking at it (even on servers?), since the above
| link
| points to descriptions of a regression in the kernel which seems more
| general.
| 
| As a side note, the Power Management Guide of Red Hat is a good
| resource (analysis tools + tuned profiles):
|
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Power_Management_Guide/
| 
| Cheers,
| 
| Mathieu
| 
| PS: Do you think I should book a bug in the upstream bug tracker?
| _______________________________________________
| CentOS mailing list
| CentOS at centos.org
| http://lists.centos.org/mailman/listinfo/centos
| 

You could also consider just sticking to tuned and then having a look at the
power management options as provided there.  tuned-adm list will show you some
predefined power management options which *can* be tweaked.

Do you know what those options due to your machine in order to make the battery
last longer?  I mean really, do you know what they do?

These could be bad options for a number of users and since it's set at
kernel boot time how can you override it once the OS has booted?  Can you
disable this without altering boot parameters and rebooting?  If the answer is
yes than a tuned configuration should be created or altered to set them
dynamically.  Setting of these at boot time are likely just wrong.  You likely
only want these to be turned on when the laptop is not attached to power, which
you can create hooks for.

This is not a bug, it's a feature/workaround on specific hardware, that
tweaks specific settings to get around a specific issue with the driver.  Create
a profile and submit it upstream.


-- 
James A. Peltier
Manager, IT Services - Research Computing Group
Simon Fraser University - Burnaby Campus
Phone   : 778-782-6573
Fax     : 778-782-3045
E-Mail  : jpeltier at sfu.ca
Website : http://www.sfu.ca/itservices
          http://blogs.sfu.ca/people/jpeltier

Success is to be measured not so much by the position that one has reached
in life but as by the obstacles they have overcome. - Booker T. Washington

On 03/08/12 17:05, Mathieu Baudier wrote:
> As per http://www.williambrownstreet.net/blog/?p=387, add the
> following kernel arguments to the GRUB boot configuration:
>
> pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
> i915.i915_enable_fbc=1
>
> As measured using PowerTop, this made the power consumption decrease
> from 20W to 11W !
> (I had already decreased it from 25W to 20W with the usual tips of
> disabling hardware, shutting down services, switching tuned profiles,
> etc.)
Thanks for the tips.  I've got a X220 and power consumption is typically 
less than 10W, with various powertop tweaks on Fedora 17, giving me 
8-9hrs of battery life.

The biggest win was setting i915.i915_enable_rc6=1 on the kernel command 
line, although I've read that this can cause some instability, depending 
on you kernel and usage -- had a couple of crashes/freezes a 6 months 
ago, but it seems pretty stable now.  The benefits for a laptop 
definitely out-weigh the inconvenience or a few rare freezes, but it 
would be different for a server.

Might try out the other kernel line options and see if I can do better :-)

Here's my /etc/rc.d/rc.local file in case you are interested:
-------------------------------------
#!/bin/bash

echo 5 > /proc/sys/vm/laptop_mode
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
for i in /sys/bus/usb/devices/*/power/autosuspend; do echo 1 > $i; done
for i in /sys/bus/usb/devices/*/power/level; do echo auto > $i; done
echo min_power > /sys/class/scsi_host/host0/link_power_management_policy
echo min_power > /sys/class/scsi_host/host1/link_power_management_policy
echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller
echo 1 > /sys/module/snd_hda_intel/parameters/power_save
for i in /sys/bus/{pci,i2c}/devices/*/power/control; do echo auto > $i; done

iwconfig wlan0 power on
-------------------------------------

Cheers,

Kal

-- 
Kahlil (Kal) Hodgson                       GPG: C9A02289
Head of Technology                         (m) +61 (0) 4 2573 0382
DealMax Pty Ltd                            (w) +61 (0) 3 9008 5281

Suite 1415
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Docklands VIC 3008 Australia

"All parts should go together without forcing.  You must remember that
the parts you are reassembling were disassembled by you.  Therefore,
if you can't get them together again, there must be a reason.  By all
means, do not use a hammer."  -- IBM maintenance manual, 1925

> I was not happy with the power consumption of CentOS 6 x86_64 on a new
> Lenovo Thinkpad x220 Tablet and I worked on reducing it. I just wanted
> to share with the list one of the changes which gave me the most
> significant improvement.
>
> As per http://www.williambrownstreet.net/blog/?p=387, add the
> following kernel arguments to the GRUB boot configuration:
>
> pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1
> i915.i915_enable_fbc=1
As a follow-up: since the update to 6.4, these kernel arguments are
*no longer required* in order to have a reasonable power consumption
on a Thinkpad X220.

With tuned profile 'laptop-battery-powersave', the idle laptop
consumes a bit more than 10W (with display turned of: 8W)