Progressive Render Slowdown in RTX GPU mode...

[HowardDay]

Continuing this thread in the beta forum...which no longer allows replies.
https://forums.chaosgroup.com/forum/...n-rtx-gpu-mode
I'm still seeing this - even simple scenes, with a box and a bunch of planes - rendering over and over (not even animation modes) and you will see a MASSIVE slowdown as you try and render. :/
"Preparing scene for frame" goes from 2 seconds to over 10 minutes.

WHY?
Here's the scene I'm testing with:
https://drive.google.com/file/d/1-CL...ew?usp=sharing
Thanks!

[HowardDay]

^Lele^ is this still being looked at?

[^Lele^]

I'd assume it is (not mine to look into).
Did you ever write an email to support pointing at the (beta) thread?
If not, please do so (linking them to the beta thread, and to this.).

[HowardDay]

Ticket #305-916-1783, apparently. I wish there was a way to check the progress of this stuff, rather than just feeling left out to hang. :/

[^Lele^]

I hear you.
On the other hand, devs are under pressure enough as it is, i can't begin to fathom what would happen with opening to the public the progress (and occasional regress. It's often a very non-linear process.) of bug fixing.
In this case, it's potentially a biggie, so rest assured resources will be poured unto it.

[HowardDay]

As a dev myself, I definitely understand that. I just hope it's an easy one to fix.

[a7az0th]

Hi Howard,

The problem is under investigation and is being actively looked in, you are not forgotten. The core of the problem lies in the way we handle compilation with LLVM. Sadly, this is not an easy fix, as the "easy" solution will break a dozen other workflows so it needs to be carefully investigated and thought of.
We'll let you know when we have progress, or, I know it's frustrating, you can try poking us every now and then to check what's going on.

[HowardDay]

..Does this one have something to do with this other bug as well? https://forums.chaosgroup.com/forum/...ar-memory-leak
Because, if so it means that animations of any sort are completely out of the question for RTX/Cuda pathways, and likely out for CPU as well. if you're using any sort of OSL. If I can only manage 18 frames at best before I have to restart MAX and sometimes the computer itself, that's a *major* bug that I hope would be a1 to fix. Or at least put an (*still frames only, restart max after several renders) besides the GPU compatibility listing for OSL.
I'm really rooting for you guys to get this fixed.

[a7az0th]

The other bug is still under investigation. I don't think they're related, but once I get more insight I'll let you know. And yes. they are a1 priority right now.

[ikomitov]

The cause of the problem is identified and we are working on a fix. As for the exact reason why it happens, it turned out to be a bad side effect of the overly aggressive shader caching strategy we employ to keep IPR more responsive. Caching more shader instances means more code for the backend to handle and exceeding a certain size becomes a problem at one point. We are evaluating better garbage collection schemes to mitigate that. The issue is certainly not left out hanging but, as Alex said, it won't be a very easy one.

Best regards,
Ivan

[HowardDay]

Any news on this bad boy? It's holding up a couple of animations I'd like to get done.
I've got a better example of the issues I'm running into. The CPU rendered version of this scene takes 21 seconds to render.
The GPU version on twin RTX TITANS takes over 9 minutes - with the vast majority of that time spent doing...nothing?
Here's the GPU version:
https://drive.google.com/file/d/1vl-...ew?usp=sharing
Here's the CPU version (stripped)
https://drive.google.com/file/d/1-Qd...ew?usp=sharing
I'm using 3dsmax 2021 and the latest 7/7 nightly.
Thanks!

[milva.perkovich]

The problem should be fixed now. Install V-Ray 5 for 3ds Max, hotfix 2, released on Jul 29, 2020 give it a try and tell us how it goes.
Best regards,
Milva

[HowardDay]

It was fixed for a while, but now it's back again. :/ I have another ticket running.