Vulkan Sync Issues on Quadro P6000/K6000 SLI Mosaic Configurations

Graphics / Linux Linux
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1

Hi everyone,

We have been experiencing synchronisation issues when trying to run Vulkan programs on our Quadro SLI comps.
We have 2 systems - Dual P6000s in SLI Mosaic and one 3x K6000s in SLI Mosaic - and are seeing the sync problem on both. It seems like it is a driver issue.

Dual P6000s

  • Frame-locked to each other using Quadro Sync II cards
  • Single monitor out for each card
  • 1x2-screen desktop configured with SLI Mosaic

3x K6000s Setup

  • Quadro Sync card used to sync cards
  • 6x2-screen desktop configured with SLI Mosaic

OS & Software

  • Both systems run Gentoo Linux with kernel v5.4
  • We are using v455.28 of the nvidia-drivers (installed through Gentoo’s package manager portage)
    • we tried other driver versions: 455.45.01, 455.38, 450.80.02, and 440.66.17 from this post. vkcube ran under 440.66.17 but was frames were stuttering and not usable
  • Vulkan Headers 1.2.143 from portage
  • Running KDE 5.19

Replicating the Issue

When we run a Vulkan program like vkcube, the viewport is shown, the first frame is rendered, then the desktop locks up for 1-5 seconds but the cursor still moves. When the desktop is responsive again, the window can’t be closed by clicking on the ‘X’, it only responds to a a kill signal or ^C in the terminal. The program then takes over 15 seconds to close.
When using VK_PRESENT_MODE_IMMEDIATE_KHR, the first frame is shown before locking up. When using VK_PRESENT_MODE_FIFO_KHR, no frames are rendered before the desktop locks up.

Occasionally, the computer will lock up and an nvidia-irq process will be running at 100% cpu and unkillable. Sometimes the comp will lock up completely requiring a reboot.

When trying to run Unreal Engine using their Vulkan renderer, the program always crashes with a VK_ERROR_DEVICE_LOST error. Changing the present mode didn’t change the error.

Attempted Workarounds

Hopefully this issue can be replicated and can be fixed in future driver releases. Until then is there anything else I can do to get Vulkan programs running on our Quadro SLI Mosaic systems?

Thanks!

2 Likes
2

Thoughts anyone? Does NVIDIA read this forum?

Since 8-Dec-2020: 220 views, no replies.

Apologies for the BUMP, but it would be good to hear something – if this issue is now understood?
… works with 1 x GPU - doesn’t work with 2 x GPUs

3

https://nvidia.custhelp.com/app/answers/detail/a_id/44/~/where-can-i-get-support-for-linux-drivers%3F

Reach them via e-mail.

4

Bump. 1.3K views.

Is anyone concerned with Vulkan + multiple GPUs + Linux SLI Mosaic desktop ?

5

SLI is dead.

555 release notes say Removed support for Base Mosaic on GeForce, which was previously available only on select GPU boards with some motherboards, and limited to five display devices.

6

thanks for the reply. Yes SLI is dead, but Base Mosaic survives on Quadro?
I’d like to qualify: we have same-model Quadro GPUs (RTX A6000s) & Quadro Sync-II card.
it’s the MOSAIC we want. Thx for the heads-up about GeForce & 555, but Quadro Mosaic is still a thing?

Updated call-out: Vulkan + multiple Quadro GPUs (with Quadro Sync-II) + Linux Mosaic desktop?

7

In my 2x3 SLI Mosaic desktop on RTX4000 cards I can run vkcube but as soon as I move it to the row of the second GPU the rendered cube disappears leaving only window borders around a black square. Same with any other Vulkan application. Interestingly glxgears and other opengl applications do not glitch like this. What’s going on nVidia?

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Yes. That’s what we see too.
Vulkan vkcube only displays on the first GPU.