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PowerTOP Can Still Extend Battery Life On Linux

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  • PowerTOP Can Still Extend Battery Life On Linux

    Phoronix: PowerTOP Can Still Extend Battery Life On Linux

    Following the recent release of PowerTOP 2.1 I did some testing from a modern Intel notebook to see what kind of power-savings one can expect from running the open-source PowerTOP software on a modern notebook running Ubuntu...

    http://www.phoronix.com/vr.php?view=MTE2NjY

  • #2
    Am I missing something about powertop? I thought one of the main features was the tunables page. IIRC, powertop used to tell you how to permanently configure these tunables. With this version, I can toggle them, but there's no indication of a /proc, /sys, etc entry that's used for configuration.

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    • #3
      I'm in the same boat as Roland, its great that PowerTOP can set them via /proc or /sys but if they dont survive reboot its fairly limited in usability. What im wondering is why we cant make /sys be able to survive reboots. Fedora has /etc/sysctl.conf (dont know if other distros also use it) so I'd think PowerTop could set the appropriate sys calls there if you change anything under the Tunables tab

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      • #4
        Originally posted by Ericg View Post
        What im wondering is why we cant make /sys be able to survive reboots. Fedora has /etc/sysctl.conf (dont know if other distros also use it)
        This doesn't really need to be standard. I have a script that runs at boot which sets a number of /sys parameters, I just want to know what powertop is doing.

        sysctl is for /proc/sys, and other distros use it either as part of the procps package or through systemd.

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        • #5
          Now if only Intel updated their Linux-ready Firmware Developer Kit... It's already been 5 years since the last release, and I can see a whole lot of <NOT ON SPEC> entries with current hardware

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          • #6
            Installing laptop-mode-tools does all the tricks

            If you install laptop-mode-tools your machine toggles all the optimizations by itself depending on power state. At least that's how it works with pure Sandy Bridge (my one's a Lenovo X220 with i5-2520). Only the VM writeback time-out isn't toggled, but that really doesn't matter much.

            I'm wondering why Ubuntu doesn't install this package by default if a battery is present.

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            • #7
              [off topic]

              Michael the phoronix watermark comes a bit in your face in many cases -and there have been complains-.

              If you want you can use the two below which i think are more subtle.

              http://i.imgur.com/CwiVb.png

              http://i.imgur.com/BNChb.png

              if you want it in svg just tell me.

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              • #8
                Originally posted by roland View Post
                Am I missing something about powertop? I thought one of the main features was the tunables page. IIRC, powertop used to tell you how to permanently configure these tunables. With this version, I can toggle them, but there's no indication of a /proc, /sys, etc entry that's used for configuration.
                It's not intuitive but if you run powertop with the --html arg it will take a snapshot and print out the available power toggles and how to do them. However it will not tell you how to do them if within powertop it says good for the various power settings listed, only if it says bad.

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                • #9
                  Does powertop get it right anyway?

                  I've looked at setting some of powertop's recommendations by hand recently and found that many of them were already set to a suitable power saving mode despite what powertop was saying. So does powertop just get it wrong sometimes?

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                  • #10
                    Michael, as the argument against too aggressive powersavings by default usually is "it kills performance!!!11!" and such I would really like you to perform benchmarks where you test this out.
                    With other words, try out the different benchmarks you usually run with stock setup and with powertops suggestions. Could be cool if you also tested if there was any changes in power consumption during the tests.

                    Is that possible?

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                    • #11
                      Good point.

                      But GNOME, KDE, etc. all have their control centres. If power management comes at a compromise, the options should at least be available there so that you don't have to be a geek/spend several hours surfing the net to power-optimise your machine.

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                      • #12
                        Originally posted by Cyborg16 View Post
                        Good point.

                        But GNOME, KDE, etc. all have their control centres. If power management comes at a compromise, the options should at least be available there so that you don't have to be a geek/spend several hours surfing the net to power-optimise your machine.
                        The thing is, I have heard that with modern hardware (i.e. newer-then-Pentium4 and alike) the penalties for powersavings should not be that bad, however because of some old hardware does have really bad penalties the peanut gallery still has a tendecy to shout "you're killing my performance!" as soon as someone says "power saving by default", and this may be something that should publicly be tested, and verified/debunked, to end those comments...

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                        • #13
                          Originally posted by HoboJ View Post
                          It's not intuitive but if you run powertop with the --html arg it will take a snapshot and print out the available power toggles and how to do them. However it will not tell you how to do them if within powertop it says good for the various power settings listed, only if it says bad.
                          Thanks! That's really useful

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