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Need help, Fusion Render slow

PostPosted: Tue Jan 05, 2021 3:25 pm
by Stephen-A
Hello! I need to get some help with my fusion render. I recently upgraded my computer's hardware to better handle fusion rendering, as we are getting into graphic design in our videos. I have a 16 second intro completely designed in Davinci Fusion that is rather intensive with nodes and connections. Prior to our upgrades, Davinci would simply crash after a few minutes trying to render it. Currently it isn't showing signs of crashing, but it's going to take 15 hours to render a 1080 version of this fusion clip.

During the render, the GPU is barely doing much, and the CPU is working anywhere between 10 to 30 percent (leaning towards the low end). My ram, however, is maxed out. Here are my specs:

CPU: AMD Ryzen 9 3950X 16-Core
GPU: Gigabyte GTX 2080 Ti 11Gb
RAM: 64 GB DDR4 3000 mhz
Motherboard: MSI MEG 570
Hard Drive: SSD 970 EVO 500GB M.2

Is there a setting that I am not aware of that will utilize more of the CPU/GPU? Thanks!!

Re: NEED HELP Fusion Render slow

PostPosted: Tue Jan 05, 2021 7:45 pm
by Kel Philm
Ram will often get maxed out on large Comps, Fusion will Cache whatever it can to improve performance so this is common.

If its running slow I would check to make sure you are utilising all the threads of the CPU, turn on simultaneous branching and set to about 8 frames (Preferences/Memory).

The other thing to check is you DoD boundaries, make sure you are not processing more than required (you may have an HD comp but it could be using a frame size that spills over to be much larger than this because of transitions, merges ...)

Re: Need help, Fusion Render slow

PostPosted: Sun Jan 10, 2021 12:31 am
by Stephen-A
Thanks for the info! I will give this a try and get back to you.

Re: Need help, Fusion Render slow

PostPosted: Sun Jan 10, 2021 12:47 am
by Stephen-A
I can't seem to locate "Simultaneous Branching". Is it no longer available in the Davinci Resolve settings?

Re: Need help, Fusion Render slow

PostPosted: Mon Jan 11, 2021 7:11 pm
by Kel Philm
Sorry, I was assuming Fusion standalone. If performance and stability is an issue I would recommend doing the comp in Fusion standalone. I only use Resolve Fusion for the simplest of tasks, otherwise I use VFX connect which is a much better workflow for me.

Re: Need help, Fusion Render slow

PostPosted: Wed Jan 13, 2021 2:27 pm
by Stephen-A
I understand. In the meantime, I do have a pressing project that I am currently trying to render in Davinci Fusion. Also, now it's not just taking a really long's also starting to crash halfway through the render.

Does anyone have any suggestions as to how I can speed up the render/prevent Davinci from crashing while rendering?

Re: Need help, Fusion Render slow

PostPosted: Wed Jan 13, 2021 3:46 pm
by wfolta
Are you using. Resolve Studio or the free version? (If you have a Resolve Studio key it works with Fusion Studio v17 -- in beta, which has less overhead than Resolve Fusion.) As Kel said, you can turn on some optimizations in Fusion Studio that might more effectively use your CPU. (Plus Fusion Studio doesn't have the overhead of Media, Color, Edit, etc, that Resolve has. On the other hand, if Fusion Studio's input is not as convenient as a MediaIn in Resolve.)

Do you have overly-large assets that are part of things? For example, you could have an 8MB TIFF of which you're only using part and you're scaling it up with Transform. Or a 4K video where you're zoomed in and only using part in an HD comp. You might use a Resize instead of a Transform to resize an asset. The idea is to use assets that are as small as possible to still get the results and quality you want. If you're forcing Fusion to keep 4x or 16x the information that will ultimately make it onto the screen, it will take much longer and be more likely to crash.

Not only might it be more likely to crash, it might waste lots of CPU/GPU cycles processing excess data, or you might see the opposite: seemingly very little CPU and GPU usage because both CPU and GPU are waiting on data being swapped around. (Particularly the GPU which will probably have less VRAM than your CPU has RAM.)

Even in Resolve Fusion it's possible to use Saver nodes to output EXR sequences (I think) and then use a Loader to import that part of your node graph and not have to re-render it if you make tweaks downstream.

Re: Need help, Fusion Render slow

PostPosted: Thu Jan 14, 2021 2:59 pm
by Marin Goleminov
One of the first things I learned about Fusion was that it is really hard to fully utilise the hardware. I was expecting all GPU and CPU cores to be maxed out, but no matter what comp I was rendering, it never happened.

I stopped trying to get to the bottom of this phenomenon, instead starting multiple instances of Fusion in order to render faster and really use all resources.

Maybe this will help with ResolveFu, too?

Re: Need help, Fusion Render slow

PostPosted: Thu Jan 14, 2021 3:21 pm
by Hendrik Proosa
Marin Goleminov wrote:Maybe this will help with ResolveFu, too?

You can't run multiple Resolve instances in parallel, and its resource overhead is humongous.