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Does Unity 2d use fewer system resources than Unity 3d? If it requires less in terms of system resources, would switching to Unity 2d increase the battery life of my Laptop?

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My main concern was battery life. I've progressively upgraded from 10.04 to 11.04 on my laptop and netbook and have lost close to 2 hours of battery life on both. –  Rob Jun 3 '11 at 15:50
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The major reason for battery life loss could be power regression in recent versions of Linux kernel. When you look at the charts, keep in mind that Lucid Lynx uses Linux 2.6.32, while Natty uses 2.6.38. –  jnv Jun 16 '11 at 19:46
    
You can "sudo apt-get install powertop" and then run "sudo powertop" to monitor CPU power (Watts) usage per process. It's a great way to see what's eating up your power. For me, it was BlueTooth, but compiz showed up as #3 behind X & Chrome. –  slacy Dec 1 '11 at 22:41

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up vote 3 down vote accepted

Definitely. Apps that are resource-hungry increase load on the hardware side (processor, bus activities, memory allocation, etcetera) and these lead to increased power consumption. If you want to optimize you battery life, I would suggest these things:

  1. Use a minimal GUI without as many fancy effects. In 11.04 you can select Ubuntu(Classic) during log-on.

  2. Turn off your wireless adapter and bluetooth adapter. Surprisingly, these adapters can suck out most of your battery life. Only turn them on when you are using them.

  3. Dim the screen to the lowest level that's practical and comfortable.

  4. Don't work in such a way that multitasking of processes in necessary, unless you need to do so.

  5. Turn off sound or use earphones. Using built-in speakers requires more power.

Try this out and you will be surprised at how long your laptop battery can last (provided the battery is not dying).

Hope this helps.

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Why is Unity definitely more resource-hungry than Unity 2D? As other posts have discussed, this is the sort of thing that one would expect to be hardware-dependent; on a machine with a good graphics card and an at least minimally OK CPU, the 3D acceleration used by Unity (via nux/compiz) should be expected to leave more resources available for use than the CPU-based ("software mode") rendering of Unity 2D (via qt4/metacity). –  Eliah Kagan Nov 26 '11 at 1:36
    
From my understanding, even if you have good 3D acceleration, the drawing is still going to be done thru the graphic card, therefore, by default, drawing 2D is less complex than 3D, logically. Therefore still, even if u have good graphic rendering system, using less computational unity 2D definitely generate less computations, thus less cpu cycles, and eventually less power consumption. –  Haikal Nashuha Dec 2 '11 at 1:19
    
Video cards are commonly used today for even non-graphical computational purposes because they solve many problems faster than CPU's. This is even though the CPU must be used to tell the video card what problems to solve. (For graphical computational problems, they have been faster for a very long time--that's why it's called 3D acceleration.) There are other problems with your reasoning as well, relating to ambiguities in defining complexity, and the implicit (incorrect) assumption that if A1 is less complex than A2 then for arbitrary machines M1 and M2, M1 runs A1 faster than M2 runs A2. –  Eliah Kagan Dec 2 '11 at 2:01
    
It uses qt-quick, instead of full-blown OpenGL stuff. –  user72421 Aug 4 '12 at 17:32
    
Downvote? qt-quick is a very top-notch GUI toolkit, it actually is moving to OpenGL in qt 5.0, but in my experience qt quick runs much better than unity-3D, even with good 3D hardware and drivers. –  user72421 Aug 4 '12 at 17:40

The battery life issue is due to a regression in the linux kernel. It doesn't have anything to do with unity.
I'm sure unity 3d's effects have some small negative effect compared to unity2d, but the best thing to do at this point is wait for a kernel version that solves the problem.

A basic overview of the regression

AFAIK kernel 3.0 still has this problem, but to a lesser degree.

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I think this really depends on your hardware, and the way you look at "less resources". If we are just talking about resources such as overall hardware, Memory and CPU utilization, leaving the question of battery aside, then your hardware needs to be considered.

If you don't have an external (to CPU) graphics card, then the statement Unity 2D uses less resources makes sense.

However, when you do have a pretty decent external graphics card, why let those resources chill at the side? Using Compiz (Unity 3D) utilizes resources available to you that otherwise would just sit there and be wasted. While in one point of view it's using more resources, but on the other hand it moves some burdens to your GPU, so it actually uses less resources on a purely CPU and memory point of view.

Just look at Phoronix's Desktop Manager Analysis

Same computer running Compiz and Metacity, and they perform about the same. So why not get the fancy effect?

in the end, it's how you look at it. And there's probably no way to know for sure which one is better on your setup until you do a test on it.

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I have the resources to run all of it. It's just that battery life has steadily dropped in my Laptop and Netbook from 10.04 up to 11.04! –  Rob Jun 3 '11 at 15:32
    
Why do you call a video card with good graphics acceleration an "external" card? These are virtually always internal cards, and many laptops have them too (and they work fine with a laptop's built-in monitor). –  Eliah Kagan Nov 26 '11 at 1:31
    
by external or internal i am referring to the CPU, not the laptop itself. –  hansioux Dec 12 '11 at 13:23

Actually, I used powertop to measure the number of wakeups, which is an indicator of power usage. Unity 3d, classic with effects, classic without effects are more or less the same as far as wakeups are concerned. Unity 2d seems to be less efficient - may be due to early stage of development. KWORKER, whatever this process is produces the most wakeups and is a process I haven't seen before.

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You should check out the jupiter power management applet, it had given me a couple extra hours on my battery.

http://www.omgubuntu.co.uk/2010/02/jupiter-awesome-netbook-powerconfig-applet/

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