Chaos Corona for Cinema 4D > [C4D] I need help!

AMD 3990X massive slowdowns

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FS-Marc:
Hi there,

We configured a Workstation with a AMD Threadripper 3990X hoping it would be a blast to work with in C4d + Corona which it is if you do rendering only. But as soon as you use the Interactive Renderer do this the whole System becomes unusable - you cant even move explorer windows without huge lags. So every speed advantage is completely lost since you cant work in your scene while IR is running.
Also Material editing seems to be extremly slow due to (I guess) rendering the preview for the material manager before updating the Viewport.

# threads override seems to work if you use a very small count like 12 - which then is too slow in rendering. If you use anything high the system breaks down again.

Has anyone any ideas or had a similar experience and knows a fix? Please let me know

Faithfully,
                 Marc


Workstation-Specs:
OS:Windows 11
Processor: AMD Threadripper 3990X
Motherboard: ASUS ROG Zenith II Extreme Alpha
Ram: 32GB ECC UDIMM DDR4 2666 x8
GPU: Geforce RTX 390
Storage: Samsung 980 Pro NVME 1 TB x2
Cooling: Noctua NH-U14S TR4-SP3
PSU: Be Quiet! Straight Power 11, 1000W

Everything runs in Stock-Settings. No OC.

Juraj:
No advice. I've built countless of workstations over the years, I have both 3990X and some of the highest Intel Dual-Xeons (provided to me by Intel itself) like 8280/8380, etc..

This is just how 3dsMax always behaved to me, but you use C4D which is interesting. Window 10 Pro/Workstation/Enterprise, Windows 11, etc.. doesn't matter.
Project Lasso, every possible setting, doesn't matter.
IR + Material Editor = Fucking hell.

Maybe it's just expectations but I've never seen other people complain about it or maybe other people just don't use heavy scenes I don't know.

It's little bit better for less-threaded machines because they keep better clocks during multi-threaded use. IR is very demanding because you're using your CPU fully multi-threaded, but still need high speed and availability of best single-core.
Windows is not exactly fantastic with process scheduling, which is finding the best available single-thread and funneling resources to it (so for example, memory access isn't hogged).
Windows 11 is little bit better in this because the scheduler has been optimized for complex architecture like LittleBIG for Intel Alder-Lake. That ultimately benefits AMD as well as it will stop Windows giving 3dsMax (or C4D or other app) to slowest thread during heavy multi-threaded use.

But I have go as far as only giving Corona 50perc. of CPU during IR. Still the same, heavy lag. Multi-seconds to edit materials in editor.

FS-Marc:

--- Quote from: Juraj on 2022-09-16, 11:36:03 ---Maybe it's just expectations but I've never seen other people complain about it or maybe other people just don't use heavy scenes I don't know.

--- End quote ---

Do you experience it only in "heavy scenes"? I made the experience that it does not matter how heavy or light the scene is.


--- Quote from: Juraj on 2022-09-16, 11:36:03 ---It's little bit better for less-threaded machines because they keep better clocks during multi-threaded use. IR is very demanding because you're using your CPU fully multi-threaded, but still need high speed and availability of best single-core.
Windows is not exactly fantastic with process scheduling, which is finding the best available single-thread and funneling resources to it (so for example, memory access isn't hogged).

--- End quote ---

Youre definetly right with that! A colleague has the 3970X and and it works like a charm. Just disappointing that its "bigger brother" is handicaped in such way.


--- Quote from: Juraj on 2022-09-16, 11:36:03 ---But I have go as far as only giving Corona 50perc. of CPU during IR. Still the same, heavy lag. Multi-seconds to edit materials in editor.

--- End quote ---

Well I guess if there is no way to resolve this we will use it as another renderslave and have to invest a bit more to get a more flexible system...


I just thought that it might be some kind of issue with the way Corona Renderer is handling things since I dont have any problems using the built in renderer in interactive mode which should also be multithreaded AFAIK.

Nejc Kilar:
So we have identified a similar issue not so long ago and are currently looking into improving things. We definitely appreciate your post here as the more configurations we know about the better.

For the time being what you can try doing is disabling the SMT in your BIOS. That will effectively be disabling multi-threading on your CPU which means you will be running with 64 cores and 64 threads instead of 64 cores and 128 threads. Without a question that is not an ideal solution because you'll lose a good chunk of performance (roughly ~20-30% or there abouts) but it beats limiting the threads inside Cinema 4D to 12 as you mentioned. The UI and everything should work quite butter smooth once you do that.

Do note that messing with the BIOS is something you're doing at your own peril. That said, it shouldn't be too difficult to find the SMT toggle :)

Just to make this super clear though, we have identified the issue and are working to fix it so the above should be a temporary solution if you're running into the issue you're mentioning.

Juraj:
Interesting.. I am curious what that could be :- ).

I think 3990X suffers from this somewhat more since the memory Controller is probably overwhelmed during Multi-threaded use, enough to create "traffic jam" for any further single-core use.
2990WX suffered from this because only half of dies had direct memory controller access, but this is no longer the case with 3990X.

But since 3970X fares better with identical IO and 280W (this 280W is shared not only by 3/4/8 respective die, but also by IO, so the IO can get starved by juice as well).

I never actually disabled SMT myself, now I will experiment as well. Def not want to dedicate my 3990X into node yet :- ).

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