Arnold GPU Rendering Crashes/Freezes

OccultMonk

I have a 3090 RTX Card with 24GB of memory. I have a scene with a head with displacement and hair. It crashes when I try to render the scene. But the VRAM memory is not full:


I also have an other Arnold problem. In render view (Interactive) the scene keeps rerendering in an endless loop (starting over every few seconds instead of refining the existing render. There is no animation in the scene. 

oglu

I assume you are on the latest GPU drivers?
And you have done the pre-populate?
Its under Arnold --> Utilities --> pre-populate GPU cache.

And i see you use a non supported material?
If you use displacement try to use less subD steps. Just as a test.

oglu

And do a full log.
https://arnoldsupport.com/2021/04/30/mtoa-getting-an-info-level-arnold-log/

OccultMonk

I did pre-populate cache. The first problem is resolved It was caused by a displacement setting. But the second problem I do not understand. In Interactive Arnold 'Renderview' it keeps re-rendering every 2 seconds from scratch instead of refining (CPU&GPU).

oglu

I had this in one scene. I fixed it with an import into a new scene.

Is this issue scene dependent? 

OccultMonk

I reimported/merged the scene in a new scene and I still got the same problem.

oglu

Could you show me your rendersettings. Are you using adaptive sampling?
Any imagers?
What does doe log say?

OccultMonk

I tried with adaptive sampling off and then it keeps rendering (So adaptive should always be off for interactive rendering?). However, when there is Ornatrix hair in the scene and I use GPU it keeps re-starting instead of refining. When I 'collapse' the hair modifier stack it keeps rendering. What could cause this?

Also, SSS with GPU is really noisy. Does this make GPU rendering for skin impractical? And does VRay a better job of this or is it inherent to GPU rendering?

With adaptive sampling on it creates these problems:

A new scene with only a simple sphere it seems to work (not sure), but when I for instance add a head with SSS or ornatrix hair it restarts again.

For CPU: When I render a scene with interactive render view this happens:
1) It starts rendering for 4-5 seconds at 100% CPU temp gets to 80c (being used)
2) It stops rendering, the CPU still runs at 100% in the task manager but the temperature of the CPU drops to 55c
3) there is some time when nothing happens (maybe 30sec to a minute) Then the CPU temp goes to 80c again and the render starts again, and this time it keeps going indefinitely (refining). It's not a CPU throttling problem!

For GPU: When I render a scene with interactive renderview this happens:

It starts rendering, and restarts and then restarts every 3-4 seconds. Only when I press on disable scene updates in the right-hand corner it keeps refining.

Here is the debug of the CPU:
(It says 24%) But task manager shows 100% on all 16 cores. 

oglu

Do a info lig like i mentioned above. Than you get the info what Arnold is doing. 

Ornatrix could be an issue. But i fear you have to talk to the Ornatrix defs. 

In any case you should post your findings on the official support forum. 

https://answers.arnoldrenderer.com/index.html