Amd and corona 10 super slow performance not using more than 50% cpu

[VASLAVO]

Good afternoon guys, here are two screenshots showing the ridiculous time to render some simple scenes and not using more than 50% of the CPU, the machines are: threadripper 3990x with the 25% workload and the threadripper 3970x with the 50% workload, additional im using a threadripper 3979x with the same issues (no screenshot), they are rendering slower than a Intel  i9 9900K, I've texted on DR and backburner, same issues.

[clemens_at]

just curious, what happens if you use a default override material? does the cpu load go up to 100% again? 

[gmh_2001]

I'm also noticing a slowdown on threadrippers here for Corona 10. I have a 3990x and 3970x and renders that previously were completing in an hour are taking 2-3 hours on 3dsmax 2024.1.

[JoeS]

Yup me to I have a 3990x while watching task manager it goes from like 7% utilisation then back to 100% and bounces around. I then turned off the caustic solver and it went back to full 100%. I am using max 2022 and windows 10.

[Avi]

There could be multiple things that can lead to this issue, let's go through them 1 by 1.

1. Make sure your workstation is properly cooled. Overheating can lead to performance throttling.
2. If you are using Windows 10 then upgrade to Windows 11 as this seems to have fixed this issue in the past, see this article for more information: https://support.chaos.com/hc/en-us/articles/5411622662289-Lower-CPU-utilization-with-Intel-Alder-Lake-processors
3. If you are using any kind of virtualization (VMware, Microsoft Server, etc.) then make sure your administrator has not limited your hardware usage.
4. Check if this is happening only with Corona and working fine with other render engines such as V-Ray.
5. Check if this issue is scene specific i.e., only happening with this scene and does not happen on other scenes.
6. Check if your workstation is not set to power-saving mode and is set to utilize full performance.

Once you do all this, please let me know about your findings.

[VASLAVO]

1. yes, all workstations with water cooling at 72 degrees top temp.
2.yes, all workstations at windows 11 with recent updates
3.Yes, using tightVNC but this behavior occurs without been connected, actually for this images I only connected to take the screenshot.
4. No, I don't have other render engines installed, only corona, this is to avoid strange behavior or errors with other render engines materials that could be imported on some models, I only have vray on a laptop with 3ssmax 2022 to convert some models from vray to corona, this machine its never used to render.
5.yes, this issue is presented on several scenes, simple and heavy, with and without caustics, displacement, animated or still.
6. No, none of my workstations are set to Powe saving mode.

ill try to upload some samples, also I've notice the caustics on the preview and the final render are different and even not existent on the final render, they appear very subtle on the caustics render channel but not on the final image, here some examples.

[Avi]

Hi,

Thanks for the prompt reply.

I would like to clarify a few more points:

1. Does this problem only occur when you're performing distributed rendering, or does it also happen when you're rendering on a single system? Is the issue consistent in both scenarios?
2. Can you let me know if it has worked previously with an older version of Corona? If you use Corona 9, do you still get 50% CPU usage?
3. Can you use our benchmark tool and let us know what is your CPU usage? You can download it from here: https://corona-renderer.com/benchmark

[VASLAVO]

Hi, im uploading 2 scenes, both same issues, caustics not existent on some shots and CPU performance below 50%

1. the problem occur on distribute, on backburnner and also local.
2. I don't see it happen on previous versions, I've noticed after some daily builds for the 10 version and now this final version this occurs a lot, almost in all scenes.
3. benchmark ok, cpu 100%

[Avi]

Thanks for your quick reply.

I can see you have raised a ticket with us. I will continue with you on the ticket.

Ticket number: 136095

[VASLAVO]

`yes, i open a ticket, here also the results for the other machines, all 100% usages with the benchmark

[gmh_2001]

We're on Windows 10 (22H2) and we're seeing this behaviour on 3970x and 3990x. Our temps are 65-70 degrees on liquid AIO. The performance with caustics is pretty poor 2-3 hour for 8 passes! Also, generally seeing some mucky gui issues with Corona 10 -attached.

[hurrycat]

Dropping my 2 cents here, I have also seen this behaviour myself on a 3970x, but it is mostly scene-dependent and possibly related to region rendering.

Observed in Corona 7, 8 and 9. Cpu drops to 30-40% utilization every couple of second before returning to 100%. It's happening rarely enough that I have learned to live with it :)

[Vlad_the_rant]

Can confirm CPU utilization below 100% with caustics on. 3970X here. CPU usage when rendering caustics hovers around 70% (average). Same scene with all caustics off - stays at 100% usage. Difference in Rays/s is around 10 million rays between caustics on and caustics off (caustics on: 6 mil. rays/s, caustics off: 16 mil. rays/s). Simple testing scene with 3 boxes and 2 planes (a mockup of a pool). Max 2024, C10.
In C9 the CPU usage was more consistent and closer to 100% regardless of caustics and the difference in speed was almost exactly double between "caustics off" and "caustics on", in rays/s (which is expected).

[maru]

We've had such reports in the past. If the CPU usage drops to exactly 50%, this usually means there is some issue with RAM. For example:
- Only two RAM sticks are installed instead of four or eight (RAM is running in dual-channel mode instead of quad-channel).
- The RAM sticks are installed incorrectly.
- The RAM sticks are not identical (e.g. different brands or the same brand but different models).
In any case, the solution is to make sure all your RAM sticks are exactly the same brand and model, they are running in quad-channel mode, and that they are installed exactly according to your motherboard manual (the correct RAM slots are populated with sticks and empty).

[VASLAVO]

Happy to answer, all ram slots are used, all same brand, same model installed correctly and purchased in the same 4 package, this issue ist presented before, i have this 4 machines for more than a year, just presented this drop of performance and also been working for this project for almost 3 months and that's how i notice the render time increased by almost 5 times in some cases so that why i pay attention to this performance and saw the cpu usage drop.