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Is PowerTop Still Useful For Extending Your Battery Life?

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  • Is PowerTop Still Useful For Extending Your Battery Life?

    Phoronix: Is PowerTop Still Useful For Extending Your Battery Life?

    Three years ago Intel had released PowerTop, an open-source utility for Linux that would analyze how well your laptop was conserving power and would allow users to easily tune their system for maximum battery life via simple power optimizations. By simply running this utility, some users were able to significantly extend their battery life. However, is this utility still useful and needed with a modern Linux desktop? The most recent release of PowerTop (v1.11) was a year and a half ago, so we are seeing how well PowerTop is still able to reduce the power consumption of Intel notebooks/netbooks running Linux.

    http://www.phoronix.com/vr.php?view=15083

  • #2
    But you know that this is not the only use for powertop, do you?!

    I once had a Volume control plugin wich was responsible for ablot 30% of my system wakeups. since this isn't funny on a laptop I replaced it with a different one so to preserve Power.
    And right now I see that the plugin container of firefox is causing 25% of the wakeups, which tells me that there are some stupidly flash ads, which aren't even seen in foreground right now that consume my poor battery. so I might think about blocking them.
    And don't forget, that working around one offending thing actually cuts your wakeups more than just the percentage the tool shows, because you also get less kernel calls and stuff.
    When is have a lot of pages flash sometimes prevents me from having an idle cpu.

    Btw. why must everyone use flash for some lousy ads? wouldn't an animated gif or something do the same job?!

    Comment


    • #3
      That article is retarded sorry.
      PowerTop is not made to run and hit the keys to activate whatever it says and boom magic battery life - windows wizard style, aren't you a tech site supposed to know that?

      The tips are just a fun option they added. The primary usage of powertop is being able to see which application is causing wake ups and draining the battery in order to optimize them. (or kill them)

      You got it quite quite wrong

      Comment


      • #4
        Well, I for one like the higher level questions of if Linux is starting to polish/refine, so I don't find it a 'retarded' article at all in concept.

        I don't think I should have to tweak/tune Linux for to get better video/battery/performance/features.

        That might have been a reasonable expectation in the earlier days where most everyone was a developer-user or power-user and the Linux/FOSS platform was a collection of bleeding edge where roughness and manual tweaking was an acceptable trade-off to have as-functional-as-possible-while-evolving desktop, but things are good enough now that refinement needs to be/is happening --- so good on Michael for exploring these questions.

        Now on the true use of the utility - well whatever, people use and abuse software for whatever they think it's useful for (hence the nature of hacking).

        It's obviously not being used (enough) for fixing CPU abusive problems (at least by Adobe) because I can walk away from my laptop for any length of time and come back and it's burning up (not quite idle)

        Comment


        • #5
          PowerTop is also very useful for confirming if Core i* family of processors utilizing Turbo Frequencies. In addition it gives some view into CStates utilization. Although turbostat gives a more complete picture.

          http://kernel.org/pub/linux/kernel/p...ols/turbostat/

          Comment


          • #6
            linux-phc

            unfortunately, it'll never become mainstream because it's risky , but if you really care about power consumption and heat, use linux-phc and try to undervolt your chips (it won't fry your chips, but it could cause data loss if it locks up during testing). I get about 20-30% more practical battery life by pushing down all the voltages on my core2 duo p8400 thinkpad sl300. Makes a world of difference. P=IV and current goes down as voltage goes down, so you get large savings. Very noticeable especially when compiling with make -j3, the heat of the laptop is about half as bad with aggressive undervolting plus a little margin of a couple of ticks for stability.

            Comment


            • #7
              Unless your CPU was designed to handle lower voltage, undervolting can actually fry it. Good thing it's not mainstream.

              Anyway, powertop does still increase my battery life. Not because I've installed it, but because it's in the hands of the developers and distributors. If there's no more improvements to make by hand-tweaking my installation, then powertop has achieved what it was designed for: good distributions that don't waste power.

              Comment


              • #8
                Originally posted by rohcQaH View Post
                Unless your CPU was designed to handle lower voltage, undervolting can actually fry it. Good thing it's not mainstream.
                and which processor that can change voltages from software isn't designed to handle lower voltages?!

                Plus I've never ever heard of a broken CPU because of too low voltages and I provably never will because to less energy will never have the energy to fry an electric connection. (That would be like saying your computer will break if you shut him down, because the shut down voltage (0V) would be too low.)

                some comments are just too stupid.

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                • #9
                  yea, all higher voltages do is make the logic transitions between cycles sharper plus make the design more robust to noise (same noise plus higher voltage means better SNR). But I'm thinking CMOS, don't know how this applies to modern designs. Overclocking and undervolting mess with the slope of the the on-off transitions and the length of time the peaks and valleys stay stable. In once case you're increasing current and heat, and in the other, you're decreasing it. but IANATransistorExpert

                  Comment


                  • #10
                    Originally posted by Ragas View Post
                    Plus I've never ever heard of a broken CPU because of too low voltages and I provably never will because to less energy will never have the energy to fry an electric connection.
                    I can't find the link right now, but IIRC that's true only if you look at an isolated CPU. There's more components inside your computer.

                    If transistors cannot function your CPU will output random nonsense. Writing weird memory values causes your programs to crash. Violating bus protocols opens up an entirely different class of failures. I doubt that consumer grade hardware is meant to fail gracefully there.

                    Also, your CPU gets signals from everyone else, and those are at a fixed voltage. There you'll see an increased voltage differential when undervolting your CPU which may or may not harm whatever's responsible for the conversion.


                    So yeah, slightly undervolting will probably result in system crashes before it physically damages anything. But if you lower it too far and got a bit of bad luck, you may end up with broken hardware.

                    Comment


                    • #11
                      Originally posted by rohcQaH View Post
                      I can't find the link right now, but IIRC that's true only if you look at an isolated CPU. There's more components inside your computer.

                      If transistors cannot function your CPU will output random nonsense. Writing weird memory values causes your programs to crash. Violating bus protocols opens up an entirely different class of failures. I doubt that consumer grade hardware is meant to fail gracefully there.

                      Also, your CPU gets signals from everyone else, and those are at a fixed voltage. There you'll see an increased voltage differential when undervolting your CPU which may or may not harm whatever's responsible for the conversion.


                      So yeah, slightly undervolting will probably result in system crashes before it physically damages anything. But if you lower it too far and got a bit of bad luck, you may end up with broken hardware.
                      I know what you mean. there were some vague reports of some Overclocker Ram destroying Undervolted AMD CPUs because the the converter wasn't constructed for such for those voltage differences.
                      But it also was never confirmed and thats a very rare cause where the RAM was running on too high voltage and the CPU on too low Voltage.

                      Actually this would be the fault of the overvolted RAM and not the undervolted CPU because the CPU gets constructed for specific voltgaes too hold and that must always be the maximum specified volages. because on peak when switching you can always have a minimum time when it goes up from minimum to full in an instant.
                      So in that case the hardware was already running out of specification and the undervoltig just gave it the rest (eveb though it's not is's fault).

                      So you are right in a way, that if you are using Undervolting you could rip open already existing hardware problems and thus sophistically kill your hardware.

                      But that won't ever happen to you because: Todays CPUs already use undervolting. they won't permit voltage changing under specified levels without really deep hacking. Using PHC on CPUs which don't meet those prerequisites makes no sense since they have no dynamic voltage scaling which is nonsense from every single aspect.

                      And the thing that at too low voltages the CPU might put out wrong results true is your own risk. But it won't kill your hardware.

                      Comment


                      • #12
                        Originally posted by rohcQaH View Post
                        I can't find the link right now, but IIRC that's true only if you look at an isolated CPU. There's more components inside your computer.

                        If transistors cannot function your CPU will output random nonsense. Writing weird memory values causes your programs to crash. Violating bus protocols opens up an entirely different class of failures. I doubt that consumer grade hardware is meant to fail gracefully there.

                        Also, your CPU gets signals from everyone else, and those are at a fixed voltage. There you'll see an increased voltage differential when undervolting your CPU which may or may not harm whatever's responsible for the conversion.


                        So yeah, slightly undervolting will probably result in system crashes before it physically damages anything. But if you lower it too far and got a bit of bad luck, you may end up with broken hardware.
                        CPU's don't operate at 1 voltage anymore, hell not even all embedded SoC's do. The the I/O portions have a supply at one voltage and the core operates at another and in some cases there are various voltages for various sections of the die. The voltages never really interact, the various portions of the chip are buffered from each other.

                        As for the P=IV crowd:

                        The actual danger is higher voltage isn't a result of this equation but rather that increasing the voltage increases leakage current in modern transistors which is responsible for most of the heat generation(wasted energy) in modern semiconductors, its been many years since leakage current wasn't the major problem in asics built on small process sizes.

                        Comment


                        • #13
                          I wonder where Michael looked for PowerTOP git...
                          probably in the wrong place ;-)

                          while Auke has been on baby leave for 2 months, we've done quite a few things before then and for example MeeGo ships what effectively is version 1.12.

                          The biggest new thing is finding those applications that keep your disk awake.

                          Also... what Michael did not write about in this article, is if PowerTOP identified applications that woke the system up a lot (more than once per second)...

                          While maybe end users can't do much with that information (other than potentially uninstalling or not starting said applications), the developers of applications and distributions can do a lot with this. For example, in MeeGo, PowerTOP is our number one tool for diagnosing any power issues, and we run it regularly to find and fix things that wake the system (cpu and/or disk) up.

                          I realize that this is not sexy end-user usage... but for developers it's key.
                          I'm glad that for normal users there's a lot less to do, that means that linux now does many more things right by default in various distributions....

                          Comment


                          • #14
                            I don't usually high-five people for doing their job or devoting time to their hobbies. But in this case I want to say that what you guys did at Intel with PowerTOP and Linux power management in general is absolutely terrific. If memory serves, between more or less 2.6.17 and 2.6.21-2 there was a revolution in terms of power savings, and not only from the kernel. PowerTOP put to shame the modules and applications that were misbehaving, forcing developers to fix them. Suddenly everybody was checking where those extra 60 wakeups came from, suggesting workarounds and testing patches to improve the situation. Getting your system to iddle at less than 10 wups/s was quite a challenge and a fun thing to do.

                            I don't know whether it's too much to say that there was a change in awareness, attitudes and coding practises as a result--I couldn't possibly know that much. But that nowadays PowerTOP doesn't spit anything terribly nasty in a default installation and power@bughost is a very low traffic mailing list is a sure sign of success.

                            Comment


                            • #15
                              Originally posted by arjan_intel View Post
                              I wonder where Michael looked for PowerTOP git...
                              probably in the wrong place ;-)

                              while Auke has been on baby leave for 2 months, we've done quite a few things before then and for example MeeGo ships what effectively is version 1.12.
                              Well, according to git.moblin.org the only changes this year is "l10n" (mostly spanish). Also is there any plan to roll out a 1.12 tag/tarball?

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