I started this in the "General Discussion" so everyone can comment even if they simply bought SS3 but are not in the limited beta.Issue:
When V Sync is enable in any form (global or by application) my average framerate tends to drop to 30 FPS when I'm not clearly getting more than 60 FPS. These 30 FPS feel like 30 frames and are not only counted wrong. Screen tearing is also present when frames are reduced to a stable 30 FPS. How ever I can also get stable framerate between 30 and 60 FPS in certain scenes, which would mean that the game doesn't try to display either 30 or 60 to minimize screen tearing as one could assume.Test Enviroment:
Linux: 3.6.7-ARCH (x86_64)
CPU: i7 2600K 4.2 Ghz
GPU: GTX 580 OC 1.5 GB VRAM
RAM: 8 GB
WM/Compositor: Gnome 3 / Mutter
SS3: Public Beta
Performance: Ultra/Ultra/UltraHow to reproduce:
Toggle V Sync either in nvidia-settings or the application settings and play the same scene twice. Activating both options doesn't change the behavior. Without V Sync - Reference Videohttp://www.youtube.com/watch?v=sKxIMjBNEA0&feature=youtu.beWith V Synchttp://www.youtube.com/watch?v=W2mRM6qGhw8&feature=youtu.be
Note: Since these videos are shot at 15 fps it might seem a bit laggy, when I move the camera fast. Doesn't represent the in-game feeling. Screen Tearing might also seem worse than it really was.
Notice the frame rate counter when I look towards the first road block and compare it to the scene without V Sync where I was getting 50-53 FPS now it is 30 FPS. Same with the last road block scene where I managed to get over 40 FPS in my first video.
If I look at the sky the behavior is as expected. V Sync limits it to 60 FPS where it would normally go to 90 FPS without it.
In the first scene where I look at the metal door my frames are 45 and they are very stable. It can stay there for as long as I want.Additional Comments:
I tested KDE 4.10, Gnome 3.6.2, Cinnamon 3D and 2D, Openbox Session without Compositing, XFCE 4.10 with compositing enable and disabled for xfwm4 window manager. In KDE you have to go to KWin settings and also disable V Sync there to get higher frame rate. Every desktop enviroment showed the same behavior.
On Windows 7 64-Bit and Direct 3D it simply caps everything above 60 FPS but doesn't go to 30 when average framerate is lower (had to crank Ultra Settings up a little bit so it would average about 48 otherwise it would be 60 all the time). V Sync also works below 60 FPS.
I think the screen tearing below 60 FPS isn't really an SS3 issue but X.Org server is to blame. Let's hope Wayland with Weston does a better job at this which is one of its goal. "Every frame is rendered perfect."