Fedora 23: KDE vs. Xfce vs. GNOME vs. LXDE vs. MATE

[mgraesslin]

The relevant questions are whether the performance differences matter, and whether they represent real sub-60fps situations. It does and they do.

No sorry, the benchmarks do not show that. You can trust me on that, I know my code.

It seems system settings no longer allows me to turn off compositing for full screen windows

Of course the setting still exists.

Thanks for reminding me of the Shift+Alt+F12 shortcut, but honestly, we need to have a default set-up that gives excellent performance. Performance matters.

Excellent performance, for whom? For productivity users or for gamers? Sorry to say, but I don't optimize for gamers. I just don't think it's worth the effort to do so on X11, because well you can optimize the shit out of X, X stays X. If gamers care about each fps, there are solutions to that: run a dedicated X and don't do anything else with the system. You don't want your facebook tab in browser to reload and waste CPU cycles in Flash. Do what a game console does: do nothing else than it. We cannot compete with a PlayStation 4 when a whole DE is running. Why should we try at all. Let's better make sure that a realistic usage scenario works fine.

[mgraesslin]

Because expecting the end-users to shift+alt+f12 for games is the way to go.

No we don't expect end-users to know that. Because of that we gave games a way to indicate that this should happen automatically.

[Del_]

Double post

[Del_]

No sorry, the benchmarks do not show that. You can trust me on that, I know my code.

Are you claiming that compositing has no effect for sub-60fps gaming?

Of course the setting still exists.

Already looked five times without finding it.

Excellent performance, for whom? For productivity users or for gamers?

For me, I fit both categories. For my kids, they actually also fit both, and they like their music player and whatnot running while they game.

[mgraesslin]

Are you claiming that compositing has no effect for sub-60fps gaming?

No, of course not. It affects the game play, just like the browser with the facebook tab does, just like any other running application affects it. We have three things to look at: 1) above 60 fps: In this area it doesn't matter if (for whatever reason we "slow down" the game). We render the 60 fps the user can at max see. 2) significantly below 60 fps: the system is not able to render the game. Yes disabling compositing might give you a few more frames, but the situation stays the same, the system is not able to render the game. In this case the environment needs to be adjusted so that the game can be rendered (close facebook for example). Situation 3) the game would be able to render at 60 fps, but KWin slows it down so that it doesn't render at 60 fps. That would be the interesting case to look at, because that's the one which would need fixing. But that the benchmark cannot show. To get this data we would have to look into the timing KWin does on rendering. We would need to know how often we missed the frame. Sorry the way how phoronix benchmarks are made, that's just not possible. And sorry also in KWin we don't have such an infrastructure yet. I'm considering to add one for the DRM backend on Wayland, because there it becomes interesting.

Already looked five times without finding it.

systemsettings -> Display and Monitor -> Compositor -> second last checkbox.

[Del_]

No, of course not. It affects the game play, just like the browser with the facebook tab does, just like any other running application affects it. We have three things to look at: 1) above 60 fps: In this area it doesn't matter if (for whatever reason we "slow down" the game). We render the 60 fps the user can at max see. 2) significantly below 60 fps: the system is not able to render the game. Yes disabling compositing might give you a few more frames, but the situation stays the same, the system is not able to render the game. In this case the environment needs to be adjusted so that the game can be rendered (close facebook for example). Situation 3) the game would be able to render at 60 fps, but KWin slows it down so that it doesn't render at 60 fps. That would be the interesting case to look at, because that's the one which would need fixing. But that the benchmark cannot show. To get this data we would have to look into the timing KWin does on rendering. We would need to know how often we missed the frame. Sorry the way how phoronix benchmarks are made, that's just not possible. And sorry also in KWin we don't have such an infrastructure yet. I'm considering to add one for the DRM backend on Wayland, because there it becomes interesting.

I see your points, thanks for sharing. My perspective is a bit different, it goes like this. 1)Some games run smoothly on all my set-ups, no issues there facebook or not. 2) Demanding games typically have graphic options I need to turn off to get decent performance, here every fps counts 3) Some games really need to run without slowdowns, because it ruins gameplay (think Counter Strike Global Offensive where you are on an online team), here every fps counts.

Getting means to do better benchmarking on wayland sounds very interesting, looking forward to see how it plays out. In the meantime, phoronix is the only place I find valuable information on the current state of graphics in linux land.

systemsettings -> Display and Monitor -> Compositor -> second last checkbox.

Ah, there it is. Thank you!