[ltp] Excessive power consumption: x220 with Fedora 15

[Christos Papadopoulos]

On 08/11/2011 04:26 PM, Dmitry E. Mikhailov wrote:
> On Thursday 11 August 2011 23:33, Christos Papadopoulos wrote:
>> Powertop reports 16-17W with machine idle. Unit is X220-4286, Intel
>> graphics and network. Is this normal? Any ideas how to reduce it?
>
> Conditions are not really well defined.
> 16W at near-full brightness with Compiz enabled, Firefox with 50 tabs opened
> and flash-animated advertisements, wireless connected could be quite normal.

I see what you are saying, but my setup is more sane than that. 
Brightness was half-full to lowest setting, no Compiz, firefox with a 
same number of tabs (~5), no annoying flash ads (I kill those tabs whn I 
don't use them), wireless is on, bluetooth is off.

What prompted my question is that my old X40 was using under 10W under 
the same conditions (closer to 8-9W).

>
> Try:
> brightness at minimum (or comfort readable minimum),

Check.

> wireless disabled (or check that wireless power saving mode is supported and
> used, check AP so it wouldn't send every beacon as "wakeup"-packet),

I need wireless to be on to do work. I don't think it's unreasonable to 
expect low power usage with WIFI on. I don't always control the AP, 
unfortunately.

> bluetooth disabled,

Check.

> set kernel laptop-mode to 5,
Check.
> mount partitions with noatime (saves quite a bit of power actually if not
> compiling smth on a battery),
> try aggressive power saving features of your HDD with hdparm (caution - it
> could shorten the HDD life and/or decrease reliability in the long run)
> check pcie_aspm enabled (could affect stability),
> check sata alpm enabled,

Hard drive is an Intel 320 SSD. Not sure how much of the above applies.

> unload usb 1.1 modules (effectively disabling it),
> disable ethernet or go to lower speed (gigabit to 100mbit may save over a
> watt),
> disable ethernet wake-on-lan (saves power in S3/STR suspend),
No ethernet connected, but will unload module and check.
> check if CPU is using ondemand governor (almost sure it does already),
Check.
> don't use compiz (or any other 3D/compositing desktop graphical candy),
Check.
> try sched_smt_power_savings=1,
Check.
> try video framebuffer compression,
Sure, but the savings appear small here.
> disable unused video outputs,
Check.
> check vm writeback time, try increasing (the chance of data loss increases
> also),
> disable syslog,
Not sure if I want to do these.
> check audio codec power saving enabled.
>
> Report again.

I did the above and also changed all the tunables under powertop. 
Overall result is that consumption dropped some, to 14W. I was hoping 
for more, but maybe I am being greedy. Reported batter time is now 4 to 
5 hours.

Still getting about 500 interrupts/sec.

Another clue is that Powertop reports the fan running at ~3400rpm. (?)

Christos.

>
>
> Best regards,
> 	Dmitry Mikhailov.