[Bug 1758685] [NEW] [Kubuntu 18.04] Persistent tearing/screen refresh problem in KWin and nvidia

[YAFU]

Public bug reported:

Kubuntu 18.04 64bits
GTX 960
==
$ uname -a
Linux yafu 4.15.0-12-generic #13-Ubuntu SMP Thu Mar 8 06:24:47 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
==
$ sudo dpkg -l | grep -i nvid
 
ii  libnvidia-cfg1-390:amd64                        390.42-0ubuntu1                             amd64        NVIDIA binary OpenGL/GLX configuration library
ii  libnvidia-common-390                            390.42-0ubuntu1                             all          Shared files used by the NVIDIA libraries
ii  libnvidia-compute-390:amd64                     390.42-0ubuntu1                             amd64        NVIDIA libcompute package
ii  libnvidia-compute-390:i386                      390.42-0ubuntu1                             i386         NVIDIA libcompute package
ii  libnvidia-decode-390:amd64                      390.42-0ubuntu1                             amd64        NVIDIA Video Decoding runtime libraries
ii  libnvidia-decode-390:i386                       390.42-0ubuntu1                             i386         NVIDIA Video Decoding runtime libraries
ii  libnvidia-encode-390:amd64                      390.42-0ubuntu1                             amd64        NVENC Video Encoding runtime library
ii  libnvidia-encode-390:i386                       390.42-0ubuntu1                             i386         NVENC Video Encoding runtime library
ii  libnvidia-fbc1-390:amd64                        390.42-0ubuntu1                             amd64        NVIDIA OpenGL-based Framebuffer Capture runtime library
ii  libnvidia-fbc1-390:i386                         390.42-0ubuntu1                             i386         NVIDIA OpenGL-based Framebuffer Capture runtime library
ii  libnvidia-gl-390:amd64                          390.42-0ubuntu1                             amd64        NVIDIA OpenGL/GLX/EGL/GLES GLVND libraries and Vulkan ICD
ii  libnvidia-gl-390:i386                           390.42-0ubuntu1                             i386         NVIDIA OpenGL/GLX/EGL/GLES GLVND libraries and Vulkan ICD
ii  libnvidia-ifr1-390:amd64                        390.42-0ubuntu1                             amd64        NVIDIA OpenGL-based Inband Frame Readback runtime library
ii  libnvidia-ifr1-390:i386                         390.42-0ubuntu1                             i386         NVIDIA OpenGL-based Inband Frame Readback runtime library
ii  nvidia-compute-390                              390.42-0ubuntu1                             amd64        NVIDIA computing metapackage
ii  nvidia-compute-no-dkms-390                      390.42-0ubuntu1                             amd64        NVIDIA computing metapackage - no DKMS
ii  nvidia-compute-utils-390                        390.42-0ubuntu1                             amd64        NVIDIA compute utilities
ii  nvidia-dkms-390                                 390.42-0ubuntu1                             amd64        NVIDIA DKMS package
ii  nvidia-driver-390                               390.42-0ubuntu1                             amd64        NVIDIA driver metapackage
ii  nvidia-kernel-source-390                        390.42-0ubuntu1                             amd64        NVIDIA kernel source package
ii  nvidia-prime                                    0.8.6                                       all          Tools to enable NVIDIA's Prime
ii  nvidia-settings                                 390.42-0ubuntu1                             amd64        Tool for configuring the NVIDIA graphics driver
ii  nvidia-utils-390                                390.42-0ubuntu1                             amd64        NVIDIA driver support binaries
ii  xserver-xorg-video-nvidia-390                   390.42-0ubuntu1                             amd64        NVIDIA binary Xorg driver
==============
=====

Hello, since many versions of Kubuntu/KWin this problem of tearing/flickering/bad refresh screen/screen synchronization when using nvidia proprietary drivers persists. The problem is that when there are fast changes in screen, you can see annoying horizontal lines/flashes. For example in videos, fast scrolling in web browsers, or applications such as Blender 3D. In Blender 3D the problem is easily verifiable and visible, simply open default cube scene, rotate the view with middle mouse button making one vertex on top of the cube to be in front of you, then quickly zoom in and out with the mouse wheel.
 
Even though this has been reported many times and marked as solved, but it has never really been solved.

The only thing that has worked for me and solves the problem (I use it since Kubuntu 14.04) is this workaround:
https://www.muylinux.com/2014/02/25/corregir-sincronizacion-tearing-nvidia-kde/

which consists of copying the following lines within this file kate "/etc/profile.d/kwin.sh":
export __GL_YIELD="USLEEP"
export KWIN_TRIPLE_BUFFER=1

The question is, would it be possible for Kubuntu or nvidia maintainers
to apply that workaround by default when you install Kubuntu or nvidia
proprietary driver?

Otherwise there are a lot of new Kubuntu users having this problem over
the years.

Thank you very much.

** Affects: kwin (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  [Kubuntu 18.04] Persistent tearing/screen refresh problem in KWin and
  nvidia

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