Realtime playback question

Hi,

I have a question about realtime playback and possible bottleneck in my system. I'm currently grading HD material (1920x1080@25fps), have a node structure of about 20 nodes (2 layer nodes, 5 parallel, and the rest are serial nodes), and this works fine in realtime (25fps), but if I add one temporal NR node at the beginning of the node three, it drops below realtime. I thought this would not be so with RTX 3090 and HD material, but it seems to be so. I was hoping not to have to do node caching with this GPU.

On the Windows Task Manager, CPU usage is about 15%, GPU usage below 40%, memory usage about 10%. disk speed is not the problem either. This is kind of weird, as there seems to be no bottleneck in the system, but still I'm getting below realtime playback when using just one Spatial NR node.


System:
CPU: Ryzen 9 3900X
RAM: 64GB @ 3200Mhz
GPU: EVGA RTX 3090 24GB, Nvidia Studio Driver 471.41
External RAID 0, speed is about 500MB/s
Windows 10 Pro 21H1
Davinci Resolve 16.2.8 Studio (also tested with version 17.2.2, same results)

Take a look at the individual core CPU and see if any single core is maxing-out. Could be that the temporal NR is not multi-threaded. That could be your bottleneck.

Is your source a GOP codec? The RAID is made of SSDs or spinners?

As a follow-on to my previous question, do you get real-time playback if all you have is the temporal NR node? (i.e., disabled all the other nodes - does it playback in real-time?).

Source is Prores HQ, and the RAID is made of two Seagate Ironwolf 8 TB drives.

I did some further testing with having an eye on CPU usage. When changing the Temporal NR frame count from 3 to 2, there was a decrease in the spikiness of the CPU usage curve on some cores. When turning Temporal NR off, the CPU usage was quite low. GPU usage was the same, regardless of the frame coun0, hovering at about 40%, and around 20% when Temporal NR was turned off.

So the CPU usage seems to be a factor.
(excuse me for the lousy photos of the usage curve..)

As a follow-on to my previous question, do you get real-time playback if all you have is the temporal NR node? (i.e., disabled all the other nodes - does it playback in real-time?).

Yeah, it's realtime with all other nodes turned off.

Well, I'm out of ideas then. ProRes should be fine. I was thinking about access times for temporal NR.