Announcement

Collapse
No announcement yet.

Nailing Down The Linux Kernel Power Regressions

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Nailing Down The Linux Kernel Power Regressions

    Phoronix: Nailing Down The Linux Kernel Power Regressions

    For those that missed it, now that I've been back in the office for a few weeks and caught up on the other benchmarks and articles for May and beginning the work for June, I'm back to looking into the Linux kernel power regressions reported more than a month ago -- i.e. Linux Has Major Power Regression and Another Major Linux Power Regression Spotted...

    http://www.phoronix.com/vr.php?view=OTUxMw

  • #2
    well done !

    Comment


    • #3
      I thought this was traced back a while ago?

      Have you tried creating a cut down bare bones kernel? This should make life much easier and quicker for bisecting over a large number of versions. Of course you'd need to check the problem still exists first in the cut down kernel

      If you need help with this Michael please give me a shout

      Comment


      • #4
        Good to see it's not forgotten. Please keep up the good work!

        Comment


        • #5
          Maybe IBM, Google, Oracle and co could be interested in supporting you? ; )
          Splendid work!

          Comment


          • #6
            are you using ccache or distcc.

            Comment


            • #7
              use a modded battery for power measurement?

              ... still needing to monitor them for manually toggling the AC power / battery. With that said, I'm still looking for a UPS power system (or a smart AC power meter) with ...
              How about modifying a worn out battery by completely removing its cells and connecting a power supply where the cells had been connected? Then do something like:

              grep "present rate:" /proc/acpi/battery/BAT0/state
              grep "present voltage:" /proc/acpi/battery/BAT0/state

              Warning: Won't eat your cat but might otherwise be harmful (or might not work at all).

              Greetings,
              Frieder

              Edit: Please check that number of cells and the voltage of power supply matches
              Last edited by frief; 06-01-2011, 05:45 PM. Reason: added caveat

              Comment


              • #8
                This dude claims that he can read out cheap power meters on his ubuntu server:
                http://www.linux-depot.com/?p=projects&s=powermeter
                http://www.eco-eye.com/products.html

                Comment


                • #9
                  Just my idea:

                  Point a web-cam to this device, do a little OCR magic and you have your numbers.

                  BTW Michael:

                  I just stumbled across a patch for (soon to arrive) version 2.6.39.1:

                  http://thread.gmane.org/gmane.linux....02/focus=12505

                  Maybe this small patch solves the power regression.

                  I'm currently building a vanilla 2.6.39 kernel with this patch applied. Tomorrow i will compare it with a completely vanilla kernel. Maybe the power consumption is significantly lower with this patch.

                  Comment


                  • #10
                    Better way to mesure power

                    Hi,

                    In order to measure power consumption I'd suggest to use multimeters instead of an UPS. The precision of the UPS is not known and it can change greatly from a manufacturer to another leading to unreproducible results.

                    A bit over your budget ($140 to $150) but a better solution would be to use two VA18B DMM with usb interface, one to measure voltage, the other to measure current and then combine the two to have power.

                    At http://www.multimeterwarehouse.com/VA18B.htm the VA18 is $70 and at http://multimeter.schewe.com/ you can get a software to read data from usb.

                    It involves a little "surgery" on the power chord in order to measure the current (you must cut one cable and attach 2 banana plugs to put the amper-meter serially) but the measures will be better then with a reading from a UPS.

                    If needed I can provide a more detailed schematic.

                    Comment


                    • #11
                      Originally posted by not.sure View Post
                      This dude claims that he can read out cheap power meters on his ubuntu server:
                      http://www.linux-depot.com/?p=projects&s=powermeter
                      http://www.eco-eye.com/products.html
                      This is a possible solution but this kind of power meter measure only the current through an Hall sensor from what I can see(Eco-eye Elite 200). I think you put manually the voltage hence any voltage variation will not be taking in account.
                      Ex: Nominal voltage is 230V an you read a consumption of 1A so the power is 230W but if the delivered voltage is only 220V (a +- 10% variation is totally normal) you will consume 220W but the reading will still be 230W. I think it's not good enough to make tests.

                      Comment


                      • #12
                        Originally posted by glasen View Post
                        Just my idea:

                        Point a web-cam to this device, do a little OCR magic and you have your numbers.
                        Too much work with too little ROI.
                        Michael Larabel
                        http://www.michaellarabel.com/

                        Comment


                        • #13
                          Originally posted by frederir View Post
                          Hi,

                          In order to measure power consumption I'd suggest to use multimeters instead of an UPS. The precision of the UPS is not known and it can change greatly from a manufacturer to another leading to unreproducible results.

                          A bit over your budget ($140 to $150) but a better solution would be to use two VA18B DMM with usb interface, one to measure voltage, the other to measure current and then combine the two to have power.

                          At http://www.multimeterwarehouse.com/VA18B.htm the VA18 is $70 and at http://multimeter.schewe.com/ you can get a software to read data from usb.

                          It involves a little "surgery" on the power chord in order to measure the current (you must cut one cable and attach 2 banana plugs to put the amper-meter serially) but the measures will be better then with a reading from a UPS.

                          If needed I can provide a more detailed schematic.
                          Too much work with too little ROI.
                          Michael Larabel
                          http://www.michaellarabel.com/

                          Comment


                          • #14
                            Voltcraft?

                            Originally posted by Michael View Post
                            Too much work with too little ROI.
                            I have a Voltcraft Energy Logger with an SD card where the data for up to ten devices can be logged. The log format needs a Windows program to be deciphered though. However there's some documentation floating around in the web that can enable you to roll your own Linux-based decoder.

                            Comment


                            • #15
                              Originally posted by Michael View Post
                              Too much work with too little ROI.
                              Hardly so. The cable work is a trivial 30min job max. The meters are natively supported under Linux, it will create a tty device and you can rewrite the data-decoding perl script from the linked site to php easily. I think frederir's is a very valid solution that will also provide you with guaranteed precision, which is something you really need and probably can't get from an UPS in this price range.

                              Comment

                              Working...
                              X