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Thread: Ubuntu: Faster, But More Power Hungry Than Mac OS X?

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  1. #1
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    Default Ubuntu: Faster, But More Power Hungry Than Mac OS X?

    Phoronix: Ubuntu: Faster, But More Power Hungry Than Mac OS X?

    Earlier this week I noted there's new Apple hardware in our labs being used to tighten up our Mac OS X support within the Phoronix Test Suite, OpenBenchmarking.org, Phoromatic, etc. However, in the middle of working on Iveland, I have been carrying out a few Mac OS X benchmarks comparing its performance under the 2010 Apple Mac Book Pro to other operating systems. With the Core i5 notebook being much faster than the past Apple Mac Minis used in comparisons like looking at their enhanced OpenGL stack and benchmarking Mac OS X against Linux and Windows 7, the results are more interesting and there's also a greater variety of testing possibilities now with the recent Phoronix Test Suite advancements. Next week there are some very interesting Apple-related benchmarks to be published, but before the weekend here are a few tests from this Apple Mac Book Pro looking at its power consumption under Mac OS X 10.6.5 and Ubuntu 10.10.

    http://www.phoronix.com/vr.php?view=15521

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    Quote Originally Posted by phoronix View Post
    [b]Phoronix: Ubuntu: Faster, But More Power Hungry Than Mac OS X?
    You should however take into consideration the "rush to idle" factor - even though Linux uses much more peak power it also finishes in a fraction of the time OS X used to complete the task, which means that completing task might have actually used much less power overall in Linux than it did on OS X. The Linux box could idle (or even sleep/shutdown) when OS X would still be hard at work, thus using very little power.

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    Quote Originally Posted by jsantala View Post
    You should however take into consideration the "rush to idle" factor - even though Linux uses much more peak power it also finishes in a fraction of the time OS X used to complete the task, which means that completing task might have actually used much less power overall in Linux than it did on OS X. The Linux box could idle (or even sleep/shutdown) when OS X would still be hard at work, thus using very little power.
    QFT.

    In other words, which system is drawing more power: one that uses 40W for 10s to get the job done or the one that only uses 30W, but for 40s?

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    As others have already said, to make a comparison you would have to integrate the instantaneous power draw over the time that it is needed to complete the task. However that's impossible to do since the CPU can change power state several times in a second and thus can power draw. Since you must have a sampling rate that's higher than the frequency of the phenomenon you are trying to measure, you can't really do that.

    If you really want to show something valuable and not those useless graphs you would have to query the initial battery charge and the final one. That's far simpler and more precise.

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    Default Peak and average power usage are very important when you using battery

    Quote Originally Posted by jsantala View Post
    You should however take into consideration the "rush to idle" factor - even though Linux uses much more peak power it also finishes in a fraction of the time OS X used to complete the task, which means that completing task might have actually used much less power overall in Linux than it did on OS X. The Linux box could idle (or even sleep/shutdown) when OS X would still be hard at work, thus using very little power.
    This is very true when you have unlimited power source with static efficiency. But here we are talking about battery. The battery capacity (Ah or mAh) is specified at optimal discharge current (Id). If you discharge the battery with greater current the battery heats up and it capacity drops rather quickly. So I suspect that Apple engineers has reduced the max/avg load by slowing down the "OS X" in order to optimize the battery capacity. Ubuntu and other distribution engineers don't have the needed data in order to do the same. They just optimize for speed. I wish I had the knowledge of the kernel and slowly over time to build library of profiles that every Linux user can use to have maximum battery life if they want.

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    Quote Originally Posted by sal-e View Post
    This is very true when you have unlimited power source with static efficiency. But here we are talking about battery. The battery capacity (Ah or mAh) is specified at optimal discharge current (Id). If you discharge the battery with greater current the battery heats up and it capacity drops rather quickly. So I suspect that Apple engineers has reduced the max/avg load by slowing down the "OS X" in order to optimize the battery capacity. Ubuntu and other distribution engineers don't have the needed data in order to do the same. They just optimize for speed. I wish I had the knowledge of the kernel and slowly over time to build library of profiles that every Linux user can use to have maximum battery life if they want.
    Do you have a reference that shows that this effect is significant when it comes to Lithium Ion batteries. I was under the impression that the discharge efficiency of Lithium Ion batteries is relatively flat in the temperatures and loads usually exerted on them.

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    Quote Originally Posted by Shining Arcanine View Post
    Do you have a reference that shows that this effect is significant when it comes to Lithium Ion batteries. I was under the impression that the discharge efficiency of Lithium Ion batteries is relatively flat in the temperatures and loads usually exerted on them.
    You'd be surprised at the differences that are taken into consideration. I don't have the data sheets here, but I do use them at work.

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    Quote Originally Posted by Shining Arcanine View Post
    Do you have a reference that shows that this effect is significant when it comes to Lithium Ion batteries. I was under the impression that the discharge efficiency of Lithium Ion batteries is relatively flat in the temperatures and loads usually exerted on them.
    Yes, the key word is "relatively". Compared to NiCd and NiMH batteries the Lithium batteries are flat, but you still need to do optimization based on the battery type and construction. Apple engineers have access to all data directly from battery manufacture. FOSS programmers don't and only very small numbers of programmers understand the limitations imposed by battery chemistry and construction.
    http://www.mpoweruk.com/performance.htm
    scroll down to "Discharge Rates" illustrates the effect of capacity offset
    If you look carefully the Phoronix results it is visible that Ubuntu don't have any power budget cap and OS X has. The power usage under Ubuntu is jumping all over, but OS X is much flatter. Apple has implemented power cap on kernel level. And I am sure this is because Apple had set battery life as priority. Other manufactures have other priorities like better performance. I think this opens opportunity for other manufactures to distinguish their offerings from the competition.

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    Quote Originally Posted by jsantala View Post
    You should however take into consideration the "rush to idle" factor - even though Linux uses much more peak power it also finishes in a fraction of the time OS X used to complete the task, which means that completing task might have actually used much less power overall in Linux than it did on OS X. The Linux box could idle (or even sleep/shutdown) when OS X would still be hard at work, thus using very little power.
    I agree. Those graphs indicate that Ubuntu is using less energy than Mac OS X for the same task. That means better energy efficiency.

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    Exactly. Integrate over time and I think you'll get significantly less power used for the same job done.

    The real question is what the power usage is for some real tasks you'd be running on a desktop, where the computer is mostly idle. Most people don't run benchmarks or CPU/GPU intensive tasks all day after all.

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