Thursday, November 16, 2017

Dell Precision 5520; NVIDIA Optimus PRIME with openSUSE TW and Leap

NVIDIA Optimus is a technology that allows an Intel integrated GPU and discrete NVIDIA GPU to be built into and accessible through a laptop. Getting Optimus graphics to work on Linux requires a few somewhat complicated steps and there are several methods to choose from.
  • disabling one of the devices in BIOS, which may result in improved battery life if the NVIDIA device is disabled, but may not be available with all BIOSes and does not allow GPU switching 
  • using the official Optimus support (PRIME) included with the proprietary NVIDIA driver, which offers the best NVIDIA performance but does not allow GPU switching unless in offload mode which doesn't work yet. 
  • using the PRIME functionality of the open-source nouveau driver, which allows GPU switching and powersaving but offers poor performance compared to the proprietary NVIDIA driver. 
  • using the third-party Bumblebee program to implement Optimus-like functionality, which offers GPU switching and powersaving but requires extra configuration. 
In this blog I'm going to focus on setting things up using the official Optimus support of PRIME output mode included with the proprietary NVIDIA driver. You can read about it here at the NVIDIA devtalk forums.

1) First we will need to disable open source nuoveau driver. You can follow the link here which will walk you through the hard way of installing and setting up the NVIDIA driver.

2) Once the NVIDIA driver is installed and nuoveau is blacklisted and the module is not loading it should look like this.
# lsmod | grep nvidia
nvidia_drm 53248 3
nvidia_modeset 843776 9 nvidia_drm
nvidia 13033472 1190 nvidia_modeset
drm_kms_helper 192512 2 i915,nvidia_drm
drm 417792 6 i915,nvidia_drm,drm_kms_helper

3) You can now begin the process of setting up your xorg.conf file to use both the Intel integrated GPU (iGPU) and the dedicated NVIDIA GPU (dGPU) in the output mode which is explained in the NVIDIA devtalk forum link above.

The below is the /etc/X11/xorg.conf I use with my Dell Precision 5520 running openSUSE TW
Section "Module"
Load "modesetting"
EndSection

Section "Device"
Identifier "nvidia"
Driver "nvidia"
BusID "PCI:1:0:0"
Option "AllowEmptyInitialConfiguration"
EndSection

Section "Device" Identifier "Intel" Driver "modesetting" BusID "PCI:0:2:0" Option "AccelMethod" "sna"
EndSection
The BusID for both cards can be discovered with this command: 
# lspci | grep -e VGA -e NVIDIA
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
01:00.0 3D controller: NVIDIA Corporation GM107GLM [Quadro M1200 Mobile] (rev a2)
The format for the BusID is explained here

4) Once you have your xorg.conf file setup right you will also need to setup your ~/.xinitrc file like this.
xrandr --setprovideroutputsource modesetting NVIDIA-0
xrandr --auto

if [ -d /etc/X11/xinit/xinitrc.d ]; then
for f in /etc/X11/xinit/xinitrc.d/*; do
[ -x "$f" ] && . "$f"
done
unset f
fi

exec dbus-launch startkde
exit 0
Of course I'm setup for KDE. If you want to load Gnome instead then change startkde to startx in your ~/.xinitrc file.

5) Reboot, Login, and enjoy your new setup with discrete NVIDIA graphics with Optimus.

Have a lot of fun!

Note: Nvidia PRIME on Linux Currently does not work like MS Windows where it offloads 3D and performance graphics to the Nvidia GPU. It works in an output method. The definition of the two methods is 

"Output" allows you to use the discrete GPU as the sole source of rendering, just as it would be in a traditional desktop configuration. A screen-sized buffer is shared from the dGPU to the iGPU, and the iGPU does nothing but present it to the screen. 

"Offload" attempts to mimic more closely the functionality of Optimus on Windows. Under normal operation, the iGPU renders everything, from the desktop to the applications. Specific 3D applications can be rendered on the dGPU, and shared to the iGPU for display. When no applications are being rendered on the dGPU, it may be powered off. NVIDIA has no plans to support PRIME render offload at this time. 

So in "Output" mode this will cause the dGPU to always be running.. I've not tested to see how this affects the battery life. 🙂 time will tell. I'll update the post to let everyone know.


resources:

https://wiki.archlinux.org/index.php/intel_graphics
https://devtalk.nvidia.com/default/topic/957814/linux/prime-and-prime-synchronization/1
http://us.download.nvidia.com/XFree86/Linux-x86_64/370.23/README/randr14.html


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