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Subsurface scattering OpenCL Crash
Closed, ResolvedPublic

Description

System Information:
CPU: Ryzen 5 2600
GPU: RX 570 4gb (Radeon Software Version: 18.11.1)
OS: Windows 10 home

Blender Version:
Broken: blender-2.80-2c2c996a1b2 (November 9th)
Worked: Blender 2.79b and Blender 2.79 Master

Short description of error:
Whenever I use a Principaled BSDF with Subsurface Scatting enabled in Cycles and the pixel count is high enough (Changing the viewport pixel size to 8x or 4x on my 1440x900 monitor resolves this issue), Blender will freeze and the screen will flash black (probably from a GPU driver crash) then Blender will remain white and "Not Responding". I would write this off as a driver issue, but seeing as these issues don't occur in Blender 2.79b or 2.79 master, it seems to be an issue with Blender 2.8 not the driver (I may be wrong on this assumption).

The error I receive from Blender after the screen flickering with the --debug-cycles argument is:

AL lib: (EE) ALCmmdevPlayback_mixerProc: Failed to get padding: 0x88890004

If I understand correctly, this is something to do with Audio and may simply be Blender interfacing with the GPU after it crashes, but I'll leave it in here just in cause I'm wrong on this assumption.

Note: Final renders don't appear to be affected by this crash. However, if the scene is official rendered (F12) then we switch back to viewport, the freezing and crashing are no longer there. However, artifacts appear:

Exact steps for others to reproduce the error:
Here's a file to test with:

Event Timeline

Philipp Oeser (lichtwerk) triaged this task as Normal priority.Nov 12 2018, 1:02 PM

@Brecht Van Lommel (brecht): not sure if you have access to such hardware, mind having a look?

I conducted another test on my Ryzen 5 2500u with Vega 8 graphics and found it experienced a similar issue. However, in the case of this GPU, a "Blue screen of death" occured with the message VIDEO_TDR_FAILURE. However, in the case of this GPU, the same issue occurs for Blender 2.79 master.

I believe the issue experienced on this system is probably more related to the low-endness of the system than the Sub-surface scattering. But it brought up the question, is the issue experienced with the RX 570 just the GPU timing out due to the complexity of the Sub-surface scattering material? With this in mind I conducted another test: A 2.79 Master scene with an indoor scene with a glass sphere, mirror, and multiple objects with sub-surface scattering. And surprisingly the GPU didn't crash.

I still believe it's an issue with 2.8 and probably Open CL.

Brecht Van Lommel (brecht) lowered the priority of this task from Normal to Incomplete.Wed, Jan 9, 11:41 AM

Can you try testing with the latest builds?

I was never able to reproduce this problem (even on a 4K monitor), but there have been some fixes in this area.