KWin Now Supports Suspended Compositing

[BlackStar]

but not everyone wants a modern desktop, particularly on Linux.

Good point.

Don't confuse "good", or "efficient" with "modern." They are different concepts.

Flashbacks to Windows 95 and Gnome 1.0.

Yes, a modern desktop *is* more efficient, because we have significantly usability research *and* hardware resources to rely on. It doesn't follow that every modern desktop is more efficient, but would you disagree that KDE4.6 is more efficient than KDE2 or that Win7 is more efficient than Win98?

[yotambien]

WTF? KWin supports tiling!
Telling KWin users to use a tiling window manager or to get in ?war? with you is like telling Christians to believe in Jesus Christ.

http://en.wikipedia.org/wiki/Tiling_window_manager

Tiling window managers. Every geek worth the title, independently or race, gender or social status, has tried one of those at some point of his l33t career. I suggest you do the same before posting again : D

Or you can try it yourself: Move a window around fast. On my aging laptop moving my almost fullscreen Firefox window around fast Xorg hogs the CPU with ~40% and the fan kicks in after a minute or so.
With compositing (despite transparency effects, shadows and such) the CPU utilization of Xorg stays low. It's at ~15% on its peak. No fan kicks in (so no overheating GPU and heat is energy which comes from the battery).

You have a point. I didn't believe it when I read it, but after trying it I found a similar behavior on my laptop. The reason why Deanjo didn't may be because he tried with a way more powerful system. If I lock the CPU to its lowest clock frequency (0.6 GHz), the difference becomes more noticeable. HOWEVER, the issue (in my case) is that the work done when compositing is active is less than what the CPU manages to push. I explain: CPU utilization with a plain old desktop almost doubles relative to that measured with the compositor on (0.6 GHz, r300, radeon set to low power state), but the window movement is smooth and responsive instead of jerky and laggy. If I set the GPU power state to 'high', the movement is much better, although still not as good as what I get with no compositing (and scrolling in Firefox still sucks). So, with my card and current drivers, I don't think compositing helps battery life at all, since I would have to set the power state permanently to the highest available, which would drain power rather quick. Dynamic power management still doesn't cut it: for a fraction of a second the movement is as jerky as when power is set to 'low', and when the GPU is automatically reclocked it catches up. Not satisfactory, especially if you also consider the visible glitches taking place when the state changes.

A quick experiment:

Gtkperf, 100 tests, CPU locked at 0.6 GHz, r300 with reasonably recent mesa and radeon drivers, KDE 4.6.1

Composite OFF, GPU power state "low":
Total time: 24.82 s (CPU up to ~85%)

Composite OFF, GPU power state "high":
Total time: 24.48 s (CPU up to ~85%)

Composite ON, GPU power state 'low'':
Total time: 65.44 s (CPU up to ~80%, most of the time at ~55%)

Composite OFF, GPU power state 'high'':
Total time: 51.64 s (CPU up to ~80%, most of the time at ~55%)

CPU utilization depends a lot on the particular operation being done, but I haven't looked at each test individually. I note, again, that Compiz performs almost like when composite is off, but I have not installed it at the moment, you'll have to believe me. I accept that newer graphics cards may show a different behavior.

[yotambien]

Of course, the last set of tests were with composite ON.

[curaga]

It doesn't follow that every modern desktop is more efficient, but would you disagree that KDE4.6 is more efficient than KDE2 or that Win7 is more efficient than Win98?

If you compare win98 on typical hw of that era, and win7 on hw of its era, the menu in 98 opens much faster than in 7. Where's your improved usability/effiency god now?

[locovaca]

It's well known that drawing from the GPU is more power efficient than by using the CPU. That's one of the primary uses GPUs are designed around, and they're very good at it.

Well, fine, then I'll show you that you're partially wrong. That's not true for all applications.

Kwin on Natty Beta 1, Intel GMA 4500HD and C2D ULV. Numbers are watt hours as measured with Powertop while on battery power. Fresh boot off of a live cd, no other apps running.

Compositing (Kubuntu Default Settings)
Idle: 12.5
Moving Window: 12.9
Playing 1080p Video: 18.2

Non-Compositing
Idle: 12.4
Moving Window: 13.4
Playing 1080p video: 17.7

[BlackStar]

If you compare win98 on typical hw of that era, and win7 on hw of its era, the menu in 98 opens much faster than in 7. Where's your improved usability/effiency god now?

The Win7 menu opens slowly for you? This is abnormal. (I'm at work and it opens up instantaneously here - instantaneously as in less than 30ms).

Besides, my Win98 system used to have 16MB RAM and a 5MB/s hard drive (Quantum Fireball 2.1GB). The menu took a long to page in back then, the system booted much slower (~2 minutes) and was much less comfortable in day to day use (no mouse acceleration, no subpixel hinting in text, no automatic spell checking in Netscape, etc).

You are looking at history through rosy glasses. Just install Win98 in VMWare and try using it for a couple of minutes. I actually do that for a program that won't run otherwise and let me tell you: it sucks. I cannot even hit the start menu reliably with the mouse, much less hit the close button on a window. Yes, newer is *significantly* more efficient here.

[curaga]

It's not been that long since I last used 98 (a fresh install at that), nor from the last time I used a fresh 7 install. It's something like 0.3s to open the menu in 98, and ~2s in 7.

Hw details for your pleasure: P2 250mhz 64mb, and Athlon X2 ~2.5ghz 2gb.

[Awesomeness]

http://en.wikipedia.org/wiki/Tiling_window_manager

Tiling window managers. Every geek worth the title, independently or race, gender or social status, has tried one of those at some point of his l33t career. I suggest you do the same before posting again : D

Epic Fail!
Scroll down to ?List of tiling window managers for X? and you'll see KWin mentioned there.
KWin has a tiling option. It's not on by default but it's there.

[BlackStar]

It's not been that long since I last used 98 (a fresh install at that), nor from the last time I used a fresh 7 install. It's something like 0.3s to open the menu in 98, and ~2s in 7.

Hw details for your pleasure: P2 250mhz 64mb, and Athlon X2 ~2.5ghz 2gb.

As I said, my Win7 menu doesn't even hesitate when clicked, it fires up instantly. I'm using a run-of-the-mill 1TB hard drive, 4GB memory and a Phenom II 555 (2-core, 3.2GHz).

[yotambien]

Epic Fail!
Scroll down to ?List of tiling window managers for X? and you'll see KWin mentioned there.
KWin has a tiling option. It's not on by default but it's there.

Look, I honestly don't think you know what a tiling window manager is. On the other hand, I don't need to read a Wikipedia article about it because I do know, and I'm perfectly aware of Kwin's tiling option. But it doesn't matter, I was kidding you.