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Linux vs. Windows Power Usage

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  • phoronix
    started a topic Linux vs. Windows Power Usage

    Linux vs. Windows Power Usage

    Phoronix: Linux vs. Windows Power Usage

    Since publishing our Ubuntu power tests, where we had monitored the power consumption of the past six Ubuntu releases going back two years on a laptop, we've had repeated requests for a power comparison between Windows and different Linux distributions. Well, in this article are the first set of results from that testing. We've compared the power consumption of Microsoft Windows XP, Windows Vista, Fedora 7, and Ubuntu 7.10.

    http://www.phoronix.com/vr.php?view=11248

  • lewis
    replied
    Ok, you do that, that sounds like the basis of an article, meanwhile I'll scratch up a script to collect similar data from acpi on any laptop and an OO spreadsheet to graph it, who knows, maybe it'll be useful or sumfink.

    Leave a comment:


  • narf
    replied
    Originally posted by lewis View Post
    Why are you obsessed with accuracy?
    We're not sending robots to mars here, just trying to get a bit of objectivity into OS efficiency.
    Test the ammeter by seeing how accurate it's battery life predictions are, that'll rule out "wildly inaccurate" easy enough.
    If it can tell me that one kernel/config/whatever is using less juice than another then it's good enough, certainly not worth ripping batteries up for.
    1. Use a dead battery. You can get them on eBay.
    2. The current sensors they use in laptops are not designed to be accurate, they are designed to give some guidance to the power saving system. Your average DVM has a much better circuit.
    3. If you want to break down your testing and try to see where individual components of the power usage are coming from, you'll want an accurate current measurement.
    4. If you use a repeatable, constant load test, you wear the battery all the way down, and you have some faith in the battery's specifications, you can use some math instead of an ammeter and bypass the whole current measuring process.
    5. If you really want to know where the power is going, you should determine the efficiency of the charging circuit, and you'll need a meter for that.

    If you want answers that you have some confidence in and feel good about defending, then you should back them up with proper testing procedure. Don't let people accuse you of being sloppy.

    Leave a comment:


  • lewis
    replied
    Originally posted by narf View Post
    If you really want to get an accurate reading of how much current is drawn from the battery, you'll have to get between the battery and the laptop. The best way I can think of to do that is to get an extra battery, rip out its guts, solder wires to the terminals inside the battery pack, and run the wires out to another battery. Now you can get in there with an ammeter and measure the true current draw. You have to at least verify what the laptop's internal current sensor is telling you. Otherwise it could be wildly inaccurate and you'd have no way of knowing.
    Why are you obsessed with accuracy?
    We're not sending robots to mars here, just trying to get a bit of objectivity into OS efficiency.
    Test the ammeter by seeing how accurate it's battery life predictions are, that'll rule out "wildly inaccurate" easy enough.
    If it can tell me that one kernel/config/whatever is using less juice than another then it's good enough, certainly not worth ripping batteries up for.

    Leave a comment:


  • narf
    replied
    better benchmarking

    Originally posted by ikaruga View Post
    Good for first start but still a little whimpish.... It's really sad when people are afraid of seeing their favorite distro performing badly.

    The whole point is to compare the two similar setups (as much as possible). In Ubuntu's case, Compiz should be enabled, as most users will want Vista's 3D effects... Also, whatever services that provide a similar Windows service should be left running...like cups, etc. The idea is also to compare a "sane" setup---a system that the average user would want.

    I would imagine power usage gives a hint of what to expect performance wise. The more power usage the slower...I imagine that that's usually true...
    You don't necessarily want all that whizzy crap turned on to make a representative test. When I'm really trying to get work done on my computer, I turn off all that silly stuff, no matter what OS I'm running, even on my high-powered desktop. It's also not representative to run a test with the CPU at 100%. Nobody actually works with their laptop running flat out. Most laptops get really loud, hot and unpleasant when you run them like that. Like I said earlier, I like the DVD movie benchmark because it runs the screen, the GPU, the DVD drive, and a relatively small amount of CPU. It's also a very easy test to run.

    Leave a comment:


  • narf
    replied
    accurately measure battery current

    If you really want to get an accurate reading of how much current is drawn from the battery, you'll have to get between the battery and the laptop. The best way I can think of to do that is to get an extra battery, rip out its guts, solder wires to the terminals inside the battery pack, and run the wires out to another battery. Now you can get in there with an ammeter and measure the true current draw. You have to at least verify what the laptop's internal current sensor is telling you. Otherwise it could be wildly inaccurate and you'd have no way of knowing.

    Leave a comment:


  • ikaruga
    replied
    Good But Still a Little Whimpish

    Good for first start but still a little whimpish.... It's really sad when people are afraid of seeing their favorite distro performing badly.

    The whole point is to compare the two similar setups (as much as possible). In Ubuntu's case, Compiz should be enabled, as most users will want Vista's 3D effects... Also, whatever services that provide a similar Windows service should be left running...like cups, etc. The idea is also to compare a "sane" setup---a system that the average user would want.

    I would imagine power usage gives a hint of what to expect performance wise. The more power usage the slower...I imagine that that's usually true...

    Leave a comment:


  • narf
    replied
    Originally posted by lewis View Post
    hack an ammeter in between the battery and laptop and run your test off ac.

    Actually don't bother:
    $ cat /proc/acpi/battery/C175/state
    present: yes
    capacity state: ok
    charging state: discharging
    present rate: 1376 mA
    remaining capacity: 3669 mAh
    present voltage: 12114 mV

    That's from a hp nx6125.

    There's your data, can you get the same in windoze?
    Don't trust any power data the laptop tells you. There's no way to verify its accuracy. Use a meter attached to the mains.

    Leave a comment:


  • lewis
    replied
    hack an ammeter in between the battery and laptop and run your test off ac.

    Actually don't bother:
    $ cat /proc/acpi/battery/C175/state
    present: yes
    capacity state: ok
    charging state: discharging
    present rate: 1376 mA
    remaining capacity: 3669 mAh
    present voltage: 12114 mV

    That's from a hp nx6125.

    There's your data, can you get the same in windoze?

    Leave a comment:


  • chron
    replied
    This Test Is Meaningless

    Testing the power usage of Linux vs Windows is futile at best. First of all, you could have optimised either platform to use less power. Assuming that you turn off all services, and underclock and undervolt the CPU. Linux ( any distro you choose ) has the advantage of being able to separate the GUI, so you can run it in a non-graphical runlevel and with no services, use a different kernel CPU governor ... and Windows will not be able to compete. However what is the purpose of this machine? Where are the real world tests or did this entire idea come to you while sitting on the porcelean throne after this mornings breakfast?

    What is the point of this test? Are you just trying to compare default installation power usages or what?

    Also, I would recommend using a method that gives you ( when dealing with watts ) at least 3 decimal places of accuracy.

    Leave a comment:

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