Arch Linux

vanja_z

Member

Registered: 2012-04-11

Posts: 43

Haswell high power usage [i5-4258U Macbook pro retina 11.1 13"]

Hi guys, I'm trying to figure out why Arch uses around twice the power of OS X when idle (and light usage). With the laptop idle, not going to sleep or turning the screen off, I measured the battery usage over 80 mins,

Arch 20% (50%->30%)
OS X 10% (50%->40%)

I have checked other smaller intervals such as 100% to 95% or 80% to 78% at various times and it always works out to be around 4 mins to drain 1% on Linux and 8 mins to drain 1% on OS X.

It is also pretty obvious during moderate usage, if I use Arch on the train on my way to and from work it drains around double the battery compared to OS X. I have checked that the battery percentage is being reported correctly and it is almost the same between the two operating systems. 30% in Arch via the acpi command corresponds to 31% under OS X and 48% to 50%.

I have tried using i7z, i7z-git and powertop to measure the power states and clocks of the cpu. i7z reports that it is sitting at 800 MHz idle and only shows the C1 state.

Socket [0] - [physical cores=2, logical cores=4, max online cores ever=2]
  TURBO ENABLED on 2 Cores, Hyper Threading ON
  Max Frequency without considering Turbo 2498.96 MHz (99.96 x [25])
  Max TURBO Multiplier (if Enabled) with 1/2/3/4 Cores is  29x/29x/29x/29x
  Real Current Frequency 799.86 MHz [99.96 x 8.00] (Max of below)
        Core [core-id]  :Actual Freq (Mult.)      C0%   Halt(C1)%  C3 %   C6 %  Temp      VCore
        Core 1 [0]:       799.86 (8.00x)           1    98.7       1       0    39      0.7793
        Core 2 [1]:       799.27 (8.00x)        3.83    98.7       0       0    33      0.7856

powertop tells me that the processor is reaching the C10 state,

          Package   |             Core    |            CPU 0       CPU 2
                    |                     | C0 active   0.1%        0.2%
                    |                     | POLL        0.0%    0.0 ms  0.0%    0.0 ms
                    |                     | C1E-HSW     0.0%    0.0 ms  0.0%    0.0 ms
C2 (pc2)   53.2%    |                     |
C3 (pc3)    3.1%    | C3 (cc3)    1.3%    | C3-HSW      0.0%    0.0 ms  1.7%    2.0 ms
C6 (pc6)   39.7%    | C6 (cc6)    0.1%    | C6-HSW      0.1%    0.1 ms  0.1%    0.6 ms
C7 (pc7)    0.0%    | C7 (cc7)   96.7%    | C7s-HSW     0.0%    0.0 ms  1.5%    2.5 ms
C8 (pc8)    0.0%    |                     | C8-HSW     13.9%   69.9 ms  0.6%    1.5 ms
C9 (pc9)    0.0%    |                     | C9-HSW      2.4%    4.9 ms  9.5%    8.7 ms
C10 (pc10)  0.0%    |                     | C10-HSW    82.8%  167.2 ms 85.9%   14.0 ms

                    |             Core    |            CPU 1       CPU 3
                    |                     | C0 active   0.1%        0.1%
                    |                     | POLL        0.0%    0.0 ms  0.0%    0.0 ms
                    |                     | C1E-HSW     0.0%    0.0 ms  0.0%    0.0 ms
                    |                     |
                    | C3 (cc3)    2.0%    | C3-HSW      2.2%    2.5 ms  0.0%    0.0 ms
                    | C6 (cc6)    0.0%    | C6-HSW      0.0%    0.0 ms  0.0%    0.0 ms
                    | C7 (cc7)   97.4%    | C7s-HSW     0.0%    0.0 ms  0.0%    0.0 ms
                    |                     | C8-HSW      0.0%    0.0 ms  0.6%    3.0 ms
                    |                     | C9-HSW     28.7%   96.5 ms  2.0%   10.3 ms
                    |                     | C10-HSW    68.9%   58.0 ms 97.0%  140.0 ms

                    |             GPU     |
                    |                     |
                    | Powered On  1.8%    |
                    | RC6        98.2%    |
                    | RC6p        0.0%    |
                    | RC6pp       0.0%    |

Does anyone have any ideas why it is using so much more juice under Linux?

vanja_z

Member

Registered: 2012-04-11

Posts: 43

Re: Haswell high power usage [i5-4258U Macbook pro retina 11.1 13"]

ok a bit of an update I've gone thru all of the steps in the wiki on power saving,
https://wiki.archlinux.org/index.php/Power_saving
it has made no real difference, now it takes just under 5 mins to drain 1%, still much worse than the 8 mins in OS X.

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,597

Website

Re: Haswell high power usage [i5-4258U Macbook pro retina 11.1 13"]

I ask of out ignorance: are the battery scales themselves consistent across operating system?  In other words, when you query the battery charge, is the software simply reading a readout from the hardware or is there some sort of calibration needed?

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vanja_z

Member

Registered: 2012-04-11

Posts: 43

Re: Haswell high power usage [i5-4258U Macbook pro retina 11.1 13"]

yeah there must be some sort of calibration involved because they don't match exactly but like I said I tested by rebooting between the two and they match within a one or two percent. 100% matches exactly, 48% Arch was 50% in OS X and likewise 30% was 31%.