Various settings for Linux stuff
The situation seems improved with the latest software and kernel 4.8. The suggestion below about SNA+xrender works well. Thanks to sibe39 for the tip. linuxmint/cinnamon#3423 (comment)
It seems the best combination is to use no xorg.conf (automatic configuration) which defaults to sna, combined with this tweak in Firefox:
Load the about:config page and change the boolean value gfx.xrender.enabled to true. This resolves the diagonal tearing seen in FF.
Here are older experiments I tried with mixed results...
If you have a laptop with Nvidia dGPU/PRIME, it's complicated to ensure there is no tearing. The simplest solution for me is to leave the dGPU off most of the time, using the Intel iGPU and adjusting the settings for the intel driver (aka xf86-video-intel, xserver-xorg-video-intel).
The file 20-intel-smooth.conf contains a settings change I found necessary to eliminate tearing. In particular, I need to use uxa or glamor, not sna for the the acceleration mode. (If you haven't specified any mode, I believe sna is the default.)
You can integrate the settings wherever you are currently sourcing your xorg.conf files. If you don't know where to put it, kill your X server and run this command from a tty:
sudo X -configure
If it doesn't complain about X already running, it will generate a starter xorg.conf and tell you where to put it.
If you're using Cinnamon/clutter, another option that may give better framerates for full-screen 3D is to use sna mode but add these lines to /etc/environment:
CLUTTER_PAINT=disable-clipped-redraws:disable-culling
CLUTTER_VBLANK=True
I found this works sometimes but there is a full-screen diagonal tear on some applications as the window rectangle is synced as two separate triangles out of sync by a frame, apparently. The issue may be resolved on newer driver builds. With uxa/glamor modes these clutter hacks seem to make occasional stuttering get worse.
Many people reported that uninstalling the intel driver and using the modesetting driver instead solved their issues. However when I try to use modesetting, Cinnamon always falls back to software rendering mode. :-/
The issue with PRIME mixed-gpu laptops is complicated and only got support recently (as of late 2016/early 2017). If you want to stop tearing when the dGPU is running, you can follow the latest instructions from Nvidia here.
On a desktop dGPU setup, there may be an easier solution. link