[BUG] [Regression] Overlay Wobble/Jitter/Artifacting introduced in 1.15.X

[mcoffin]

Description

Starting with SteamVR 1.15.X, overlays (via IVROverlay from a game client, and the "system" overlay displayed when you hit the "system" button on the index controllers), wobble, as if they are attached to the HMD with a rubber band. If you move around enough, there will also be significant artifacting ocurring in the overlays (though it's a little harder to induce with the system overlays compared to the IVROverlay instances created by ACC).

This only occurs when asynchronous reprojection is enabled.

Reproduction Steps

Steps to reproduce the behavior:

1. Launch SteamVR 1.15.2
2. Open system overlay
3. Move your head around

Expected Behavior

The overlay should stay static in space, and not have artifacts, as it did in SteamVR 1.14.16.

System Information

• Distribution: Arch Linux (amd-staging-drm-next kernel - f24cd554aacf4e989a0796c7d30d758115512732 rebased off of v5.9-rc6 from Linus' tree with rebased futex patches from mcoffin/linux@mcoffin-5.10-futex-wait-multiple, but this behavior is observed on stable channel kernels as well)
• Exact kernel (though likely non-factor since reproducible on stable channel as well) - mcoffin/linux@7d4ad53
• SteamVR version: 1.15.2 (working: 1.14.16)
• Steam client version: Built: Sep 3 2020 at 21:18:20
• Opted into Steam client beta?: No
• Graphics driver version: Mesa 20.2.0 (git-663d464366) (ACO), AMD Radeon RX 5700 XT (NAVI10, DRM 3.40.0, 5.9.0-rc6-1-amd-staging-drm-next-git-00457-g3637df487bdb, LLVM 11.0.0). Mesa versions down to 20.1.4 were also tried, with no change in behavior. Regression still occurs between 1.14.X and 1.15.X.
• Gist for SteamVR System Information: https://gist.github.com/mcoffin/bc4460030a4414e8929c78e252a80766
• CPU: AMD Threadripper 3960X

Additional Context

A cpu profile with sysprof shows a significant amount of time being spent in clock_gettime compared to "working" versions. (~10% of samples for ACC with it open!). This could indicate a busy-wait somewhere that's misbehaving?

Mesa 20.2.0 released a whole bunch of RADV features for timeline syncobj's, and I chased down that path for a while, but observing the same behavior with previous mesa releases ruled the timing of this release out as the issue.

Under normal operation, I'm running a pretty hefty GPU overclock, and setting the min frequency to quite close to the max to achieve livable performance, but disabling this (clean boot with no writing to sysfs), did not affect the observed behavior in any way.

• perf top during overlay wobble for ACC

Screenshots

Unfortunately, overlays are only displayed in the HMD for me, so I cannot capture this behavior, though I can look in to alternative solutions if upstream developers cannot readily reproduce the issue.

In-progress debugging

• Hook up a 2070 super from my GF's computer to see if the problem is isolated to amdgpu/mesa interactions with SteamVR
• Downgrade mesa pre-timeline-syncobj implementation (result: no change)
• Use stable kernels (result: no change)

[mcoffin]

New note: This only occurs when asynchronous reprojection is enabled.

[Zamundaaa]

Same here.

System Information (please complete the following information):

• Distribution: Manjaro KDE
• SteamVR version: 1.15.2
• Steam client version: 1602115886
• Opted into Steam client beta?: yes
• Graphics driver version: Mesa 20.1.8 (LLVM 10.0.1)
• SteamVR System Information: SteamVR-2020-10-09-PM_03_08_42.txt

[WebFreak001]

can reproduce:

Distribution: Arch Linux (5.9.2-zen1-1-zen)
SteamVR version: tested 1.15.2 - 1.15.5 (worked in 1.14.16)
Steam client version: Built: Oct 28 2020 at 23:35:02
Opted into Steam client beta?: Yes
Graphics driver version: Mesa 20.2.1 on AMD Radeon RX 5700 XT (NAVI10, DRM 3.39.0, 5.9.2-zen1-1-zen, LLVM 10.0.1)
Gist for System Information: https://gist.github.com/WebFreak001/8fe9ab2ad916efc11a42c483fb6b44b5
SteamVR System Information: https://gist.github.com/WebFreak001/35b7e824996ec98d763bb6978a74f2c7
CPU: AMD Ryzen 7 1700X

[duckbytes]

I have this problem too and now that the beta has been pushed into the main release branch it can no longer be avoided by opting out of the beta.

Distribution Arch Linux
Linux 5.9.8-zen1-1-zen #1 ZEN SMP PREEMPT Tue, 10 Nov 2020 22:44:06 +0000 x86_64 GNU/Linux
mesa 20.2.2-2
AMD 5700XT
AMD 3700X

Edit: the problem also effects xrdesktop windows.

[hex3562]

Can reproduce

SteamVR version: 1.15.10
Distribution: Arch Linux
Linux 5.9.8-zen1-1-zen #1 ZEN SMP PREEMPT Tue, 10 Nov 2020 22:44:06 +0000 x86_64 GNU/Linux
Mesa 21.0.0-devel
AMD Radeon RX 580 Series (POLARIS10, DRM 3.39.0, 5.9.8-zen1-1-zen, LLVM 11.0.0)
AMD Ryzen 5 3600

[lostgoat]

There is a linux_1.14 branch available in SteamVR as a temporary solution to this problem.

[supernovajm]

Can reproduce, but not just the overlay. Timing-sensitive games like Beat Saber felt significantly more choppy, which the fps graph confirmed.

SteamVR version 1.15.10
Distribution: Kubuntu 20.04
Linux 5.4.0-54-generic
mesa 20.3.0-rc2
AMD Radeon RX 5700
AMD Ryzen 5 3600

[kedodrill]

There is a linux_1.14 branch available in SteamVR as a temporary solution to this problem.

@lostgoat Could I ask what are the details for the system that Valve uses for testing SteamVR on Linux? It has been awhile since there has been a Linux update, specifically for performance. Are there things specifically preventing Valve from getting SteamVR working with good performance (close to / matching Windows) on Linux?

[anadon]

I'm hitting something that may or may not be related.

https://gitlab.freedesktop.org/mesa/mesa/-/issues/4044

[WebFreak001]

@anadon what you are experiencing might rather be related to #377 (which for me happened because of different vulkan driver)

check the solutions I posted there to see if that fixes it for you