PRIME
PRIME is a technology used to manage hybrid graphics found on recent desktops and laptops (Optimus for NVIDIA, AMD Dynamic Switchable Graphics for Radeon). PRIME GPU offloading and Reverse PRIME are an attempt to support muxless hybrid graphics in the Linux kernel.
PRIME GPU offloading
We want to render applications on the more powerful card and send the result to the card which has display connected.
The command xrandr --setprovideroffloadsink provider sink can be used to make a render offload provider send its output to the sink provider (the provider which has a display connected). The provider and sink identifiers can be numeric (0x7d, 0x56) or a case-sensitive name (Intel, radeon).
xf86-video-* or built-in modesetting) drivers from the official repositories, as they have DRI3 enabled by default and will therefore automatically make these assignments. Explicitly setting them again does no harm, though.Example:
$ xrandr --setprovideroffloadsink radeon Intel
You may also use provider index instead of provider name:
$ xrandr --setprovideroffloadsink 1 0
For open source drivers - PRIME
To use your discrete card for the applications who need it the most (for example games, 3D modellers...), prepend the DRI_PRIME=1 environment variable:
$ DRI_PRIME=1 glxinfo | grep "OpenGL renderer"
OpenGL renderer string: Gallium 0.4 on AMD TURKS
/sys/bus/pci/devices/, but prefix with pci- and replace semicolons and dots by underscores, e.g. DRI_PRIME=pci-0000_01_00_0.Other applications will still use the less power-hungry integrated card. These settings are lost once the X server restarts, you may want to make a script and auto-run it at the startup of your desktop environment (alternatively, put it in /etc/X11/xinit/xinitrc.d/). This may reduce your battery life and increase heat though.
See Gentoo:AMDGPU#Test, if a discrete graphics card is in use for more information.
For DRI_PRIME to work on Vulkan applications vulkan-mesa-layers needs to be installed, as well as lib32-vulkan-mesa-layers for 32 bit applications.
PRIME render offload
NVIDIA driver since version 435.17 supports this method. The modesetting, xf86-video-amdgpu (450.57), and xf86-video-intel (455.38) are officially supported as iGPU drivers.
To run a program on the NVIDIA card you can use the prime-run script provided by nvidia-prime:
$ prime-run glxinfo | grep "OpenGL renderer" $ prime-run vulkaninfo
PCI-Express Runtime D3 (RTD3) Power Management
Open-source drivers
Kernel PCI power management turns off the GPU when not used with PRIME offloading or reverse PRIME. This feature is supported by modesetting, xf86-video-amdgpu, xf86-video-intel, xf86-video-nouveau drivers.
The following command can be used to check current [1] power state of each GPU:
$ cat /sys/class/drm/card*/device/power_state
NVIDIA
- No configuration is generally needed for Ampere as this is enabled by default. For some Ampere users, udev rules may be necessary.
- Some users with hybrid graphics are reporting that their discrete NVIDIA Ampere GPUs are failing to remain in the D3Cold power state after upgrading to newer NVIDIA drivers (seemingly >525) [2].
- Some users with pre-Ampere card and broken D3 support on newer drivers reported a workaround to disable the GSP firmware with
NVreg_EnableGpuFirmware=0[3].
For Turing generation cards with Intel Coffee Lake or above CPUs as well as some Ryzen CPUs like the 5800H, it is possible to fully power down the GPU when not in use.
The following udev rules are needed, as recommended by NVIDIA:
/etc/udev/rules.d/80-nvidia-pm.rules
# Enable runtime PM for NVIDIA VGA/3D controller devices on driver bind
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"
# Disable runtime PM for NVIDIA VGA/3D controller devices on driver unbind
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="on"
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="on"
Some users also reported that the following additional lines are necessary too:
/etc/udev/rules.d/80-nvidia-pm.rules
# Enable runtime PM for NVIDIA VGA/3D controller devices on adding device
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"
Also, add the following module parameters:
/etc/modprobe.d/nvidia-pm.conf
options nvidia "NVreg_DynamicPowerManagement=0x02"
Alternatively, you can install nvidia-prime-rtd3pmAUR which provides these two configuration files.
After you setup the udev rules and the module parameter either manually or using the AUR package, you will need to restart your Laptop.
To check if the NVIDIA GPU is turned off you can use this command:
$ cat /sys/bus/pci/devices/0000:01:00.0/power/runtime_status
You will see either suspended or running, if suspended is displayed, the GPU is turned off. Now the power draw will 0 Watts making the battery last longer.
In some cases, such as the NVIDIA RTX A1000, none of the options above might be listed and instead the result will be active. This alone does not mean that the GPU is in the running state. In this case you can check the state using this command:
$ cat /sys/bus/pci/devices/0000:01:00.0/power/runtime_suspended_time
While the GPU is in suspended state, the counter will be incrementing every time you run the command. When the GPU's state becomes running it will stop incrementing.
We also need to enable nvidia-persistenced.service to avoid the kernel tearing down the device state whenever the NVIDIA device resources are no longer in use. [4]
Configure applications to render using GPU
Even without enabling Dynamic Power Management, offload rendering of applications is required [5].
To run an application offloaded to the NVIDIA GPU with Dynamic Power Management enabled, add the following environment variables: [6]
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia command
When using on a Steam game, the launcher command line can be set to:
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia %command%
GNOME integration
For GNOME integration, install switcheroo-control and enable switcheroo-control.service.
GNOME will respect the PrefersNonDefaultGPU property in the desktop entry. Alternatively, you can launch applications with GPU by right clicking on the icon and choosing Launch using Discrete Graphics Card.
Troubleshooting
If you have bumblebee installed, you should remove it because it blacklists the nvidia_drm driver which is required to load the NVIDIA driver by X server for offloading.
PRIME synchronization
When using PRIME, the primary GPU renders the screen content / applications, and passes it to the secondary GPU for display. Quoting an NVIDIA thread, "Traditional vsync can synchronize the rendering of the application with the copy into system memory, but there needs to be an additional mechanism to synchronize the copy into system memory with the iGPU’s display engine. Such a mechanism would have to involve communication between the dGPU’s and the iGPU’s drivers, unlike traditional vsync."
This synchronization is achieved using PRIME sync. To check if PRIME synchronization is enabled for your display, check the output of xrandr --prop.
To enable it run:
$ xrandr --output <output-name> --set "PRIME Synchronization" 1
- A pre-requisite for PRIME synchronization with the NVIDIA driver is to enable modesetting.
- PRIME synchronization is not available with the AMDGPU DDX driver (xf86-video-amdgpu).
Reverse PRIME
- Reverse PRIME is not supported for AMDGPU + NVIDIA on NVIDIA driver prior to 470 beta. See [7] for more details. An alternative for older versions is to use NVIDIA as the primary card as described in #Discrete card as primary GPU.
- Currently when only external display is enabled, you will only get 1 FPS. See [8] for more details.
If the second GPU has outputs that are not accessible by the primary GPU, you can use Reverse PRIME to make use of them. This will involve using the primary GPU to render the images, and then pass them off to the second GPU.
It may work out of the box, however if not, please go through the following steps.
Configuration
First, identify integrated GPU BusID
lspci -d ::03xx
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile) 01:00.0 VGA compatible controller: NVIDIA Corporation TU117M [GeForce GTX 1650 Mobile / Max-Q] (rev a1)
In the above example Intel card has 00:02.0 which translates to PCI:0:2:0.
Set up your xorg.conf as follows and adjust BusID.
/etc/X11/xorg.conf
Section "ServerLayout"
Identifier "layout"
Screen 0 "intel"
Inactive "nvidia"
Option "AllowNVIDIAGPUScreens"
EndSection
Section "Device"
Identifier "nvidia"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "nvidia"
Device "nvidia"
EndSection
Section "Device"
Identifier "intel"
Driver "modesetting"
BusID "PCI:0:2:0"
EndSection
Section "Screen"
Identifier "intel"
Device "intel"
EndSection
The command xrandr --setprovideroutputsource provider source sets the provider as output for the source. For example:
$ xrandr --setprovideroutputsource radeon Intel
When this is done, the discrete card's outputs should be available in xrandr, and you could do something like:
$ xrandr --output HDMI-1 --auto --above LVDS1
to configure both internal as well as external displays.
Known issues
If after reboot you only have one provider, it might be because when Xorg starts, the nvidia module is not loaded yet. You need to enable early module loading. See NVIDIA#Early loading for details.
Troubleshooting
XRandR specifies only 1 output provider
Delete/move /etc/X11/xorg.conf file and any other files relating to GPUs in /etc/X11/xorg.conf.d/. Restart the X server after this change.
If the video driver is blacklisted in /etc/modprobe.d/ or /usr/lib/modprobe.d/, load the module and restart X. This may be the case if you use the bbswitch module for NVIDIA GPUs.
Another possible problem is that Xorg might try to automatically assign monitors to your second GPU. Check the logs:
$ grep "No modes" ~/.local/share/xorg/Xorg.0.log
AMDGPU(0): No modes.
To solve this add the ServerLayout section with inactive device to your xorg.conf:
/etc/X11/xorg.conf
Section "ServerLayout" Identifier "X.org Configured" Screen 0 "Screen0" 0 0 # Screen for your primary GPU Inactive "Card1" # Device for your second GPU EndSection
When an application is rendered with the discrete card, it only renders a black screen
In some cases PRIME needs a composite manager to properly work. If your window manager does not handle compositing, you can use a compositor on top of it.
If you use Xfce, you can go to Menu > Settings > Window Manager Tweaks > Compositor and enable compositing, then try again your application.
Black screen with GL-based compositors
Currently there are issues with GL-based compositors and PRIME offloading. While Xrender-based compositors (xcompmgr, xfwm, compton's default backend, cairo-compmgr, and a few others) will work without issue, GL-based compositors (Mutter/muffin, Compiz, compton with GLX backend, Kwin's OpenGL backend, etc) will initially show a black screen, as if there was no compositor running. While you can force an image to appear by resizing the offloaded window, this is not a practical solution as it will not work for things such as full screen Wine applications. This means that desktop environments such as GNOME3 and Cinnamon have issues with using PRIME offloading.
Additionally if you are using an Intel IGP you might be able to fix the GL Compositing issue by running the IGP as UXA instead of SNA, however this may cause issues with the offloading process (ie, xrandr --listproviders may not list the discrete GPU).
For details see FDO Bug #69101.
One other way to approach this issue is by enabling DRI3 in the Intel driver. See the below issue for a sample configuration.
GNOME
You may find that disabling fullscreen undirect allows PRIME offloading to work correctly for full-screen applications.
Kernel crash/oops when using PRIME and switching windows/workspaces
Using DRI3 WITH a configuration file for the integrated card seems to fix this issue.
To enable DRI3, you need to create a configuration for the integrated card adding the DRI3 option:
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "DRI" "3"
EndSection
After this you can use DRI_PRIME=1 WITHOUT having to run xrandr --setprovideroffloadsink radeon Intel as DRI3 will take care of the offloading.
Glitches/Ghosting synchronization problem on second monitor when using reverse PRIME
This problem can affect users when not using a composite manager, such as with i3. [9]
If you experience this problem under Gnome, then a possible fix is to set some environment variables in /etc/environment [10]
CLUTTER_PAINT=disable-clipped-redraws:disable-culling CLUTTER_VBLANK=True
Error "radeon: Failed to allocate virtual address for buffer:" when launching GL application
This error is given when the power management in the kernel driver is running.
You can overcome this error by appending radeon.runpm=0 to the kernel parameters in the bootloader.
Constant hangs/freezes with Vulkan applications/games using VSync with closed-source drivers and reverse PRIME
Some Vulkan applications (particularly ones using VK_PRESENT_MODE_FIFO_KHR and/or VK_PRESENT_MODE_FIFO_RELAXED_KHR, including Windows games ran with DXVK) will cause the GPU to lockup constantly (~5-10 seconds freezed, ~1 second working fine)[11] when ran on a system using reverse PRIME.
A GPU lockup will render any input unusable (this includes switching TTYs and using SysRq functions).
There is no known fix for this NVIDIA bug, but a few workarounds exist:
- Turning Vsync off (not possible for some applications)
- Turning PRIME Synchronization[12] off (will introduce screen tearing):
xrandr --output HDMI-0 --set "PRIME Synchronization" 0 #replace HDMI-0 with your xrandr output ID
You can verify if your configuration is affected by the issue simply by running vkcube from the vulkan-tools package.
Some programs have a delay when opening under Wayland
If you have RTD3 working (from #NVIDIA), when using Wayland you will experience some delay when a program opens, this is because it tries to power on the GPU first (which it takes ~1 second or more) and then it tries to open the program, wasting time and battery life. This is an NVIDIA driver problem. More details here
To solve this, add these 2 lines in your /etc/environment file:
/etc/environment
__EGL_VENDOR_LIBRARY_FILENAMES=/usr/share/glvnd/egl_vendor.d/50_mesa.json __GLX_VENDOR_LIBRARY_NAME=mesa
Error when running Wine games with DXVK
When using PRIME offload, encountering the Major opcode of failed request: 156 (NV-GLX) is a know problem. The only known workaround is to start X session entirely on NVIDIA GPU. A user friendly way to switching between NVIDIA only and PRIME offload method is the optimus-manager utility or write some automation scripts yourself.