Corona not using cpu power

[Hendrik98]

Hello Corona Forum,

i have the following problem. When im rendering my scene, corona is taking hours for the "computing sec. GI" task.
The rendering time is so long, even for little scenes. The strange thing is, that i only have this problem since a few days. Before it worked completly fine.
When im opening my task manager, it shows me that 3dsMax is only using a few percent of my cpu and 100% of my disk. I have put some pictures in the attachment.
It would be super nice if someone could help me with this problem because i really dont know what i can do about this. Thank you and have a nice day!

[sprayer]

If you have 16gb ram that's not enough, corona take from hdd what is slow, that's why speed slowing down. You can try optimize scene, but corona needs at least 32gb of ram to work comfortable

[Hendrik98]

i know that 16gb is low, but then i dont understand why it worked fine before

[sprayer]

It because you make scene before more lighter for ram. Close all not needed programs, browser etc. Maybe you insert objects with displacement, you can try to disable it, convert textures to jpg and reduce resolution if possible. Do not use lightmix and render elements. There is few option in corona what can reduce ram usage, and you can try to turn off VFB, setup save or autosave of rendering crx, this is also may reduce usage of ram. Restart 3ds max before rendering.

[Byteman3D]

I'm not sure it is about low ram as the CPU usage percent resembles single core operation. I use a Dell workstation and on some occasions, I have the exactly similar single core operation instead of all core usage. Used to happen with Mental Ray in my case. Never had it with Corona. Could never understand why. Restarting the computer solved in my case.

I wonder if the grass might be the reason. Hide the objects and give it a try. You may also try hiding many objects and leave a simple ground plane to see if it reaches the expected 100% Cpu use. One by one, revealing the rest of the object might help you pinpoint.

Good luck.

[b.roque]

Hello all.
I have the same problem. Some one can help me please?
Thank you

[TomG]

Well, running low on RAM could cause this, because the CPU has to sit idle while waiting for data to come from the hard drive rather than from memory, and that is orders of magnitude a bigger wait. So the first thing to do is optimize the scene to get it working within the memory restrictions (or add more RAM) - only if the low CPU utilization remains after that would there be something to look into. For now though, it's not surprising that the CPU is idle, as it can't do anything til it gets the data it needs.

[b.roque]

Well, running low on RAM could cause this, because the CPU has to sit idle while waiting for data to come from the hard drive rather than from memory, and that is orders of magnitude a bigger wait. So the first thing to do is optimize the scene to get it working within the memory restrictions (or add more RAM) - only if the low CPU utilization remains after that would there be something to look into. For now though, it's not surprising that the CPU is idle, as it can't do anything til it gets the data it needs.

Thank you TomG.
I took 30 min with 4k res and no render elements, and now I tried it with 8k and render elements.