Pr Resource Use - CPU/GPU

[PhotogCda]

I have a graphics card that is compatible with GPU acceleration and I have GPU acceleration turned on in Settings.

To try and see how Pr uses resources, I've had a system monitor open while rendering a recent project.

The beginning of the project (~35-40 seconds) is all animation.  Assets were created in Ps, imported into Pr with motion added via the Effects panel in Pr.  These same assets are in different places on the timeline at various points in the film.

Looking at the resource monitor, when these animation elements are being rendered, GPU use is high.  This makes sense.  GPU use then drops when standard video segments are being rendered.  This, too, makes sense.  The video card is a Radeon RX580 with 4GB of on card RAM.

When it comes to the CPU, when rendering the animations, CPU use is high (90%+).  I've got an 8-core processor at 3.1 GHz with 16GB of RAM installed (not sure of the RAM clock speed).  When the rendering hits standard video segments, including assets that have been modified in Ae, CPU use drops dramatically into the 30-35% range.  Then, when it comes to the animations again, resource use goes back to 90%+.  Obviously, by using fewer available resources, overall rendering times are slowed.  This project; a 69 minute film with ~25-30% of Ae comps for noise reduction, takes about 16 hours to render in h.264 at ~16Mbps.  I know the Ae comps take longer to render.  Before those were added, the project exported in just over 1 hour.

Is there any insight into why Pr makes such poor use of system resources when rendering standard video segments?  Or is it something that's not universal?

[Moderator note: moved to appropriate forum.]

[R Neil Haugen]

One thing that might be a factor, is you've only got what, 2Gb of RAM per core ... that is probably limiting the CPU dramatically in the H.264 work. I know for building rigs for working with H.264, I've seen the suggestion that one would want 8-10GB of RAM per core to keep the CPU running hard.

But hopefully some of our tech wizards can give help on this.

Neil

[PhotogCda]

'Affordable' mobos 6 years ago when this machine was built didn't allow for 64-80GB of RAM.  I know that's common now in 'run of the mill' mobos.

So what you're saying is my computer is simply too old?  That wouldn't be surprising.  That still doesn't explain the difference in when/how the CPU ramps up activity.  Or is it possibly a matter that the graphics/animations are less RAM intensive overall, or because they make use of the GPU RAM that allows the CPU to work harder. 

[R Neil Haugen]

I think that later assumption might be correct, GPU stuff uses that RAM, but straight encoding is a CPU cores/RAM task. In my understanding  ... but don't place any massive bets on that ...

Neil

[PhotogCda]

My board only supports 32GB, so that's the best I could do in any case. 

[R Neil Haugen]

Well, I've got 32, and when I went from 16 to 32, was pleased with the result. Not that I'd mind working a 10-core 4.2Ghz machine with 128GB of RAM, mind you ... lol

Neil

[PhotogCda]

I just spent nearly $500 replacing the video card because my liquid cooling system leaked and fried the old one.  RAM isn't cheap right now, so it may have to wait a couple months.

[R Neil Haugen]

Yowza, GPU's are spendy now. Totally understand. That 10-core I dream of is something the wife says fuhgedabout it ... sigh.

Neil

[PhotogCda]

Interestingly, about a week after the new video card was installed, the GPU/CPU usage is very different during rendering.  Now, when rendering the standard video segments CPU usage is generally 85%+, occasionally dipping to about 80%, but only for a second.

GPU usage is still high on the animation segments, which is expected, and good.  It's the change in CPU usage that is strange.  Nothing else has changed on the hardware side.  Some of the Ae comps have been replaced with standard video segments as I found a better way to deal with the noise issue.  That should only result in a faster render time, not higher CPU use.  And it does - about 6 hours now rather than the previous 17.  The fewer Ae comps will account for some of that, but the resource use will impact it as well.  Even on the remaining Ae comps (Warp Stablizer), CPU use is high.

Do GPUs have a bed-in time like audio components?  I ask that facetiously because I know it's not the case.  It just seems odd how the resource use has changed roughly a week into having the new card installed (about 5 days, really, as the improvement started on the weekend).

[R Neil Haugen]

Great question!

Or do computers have ... well, not gremllins per se, but little live characters of some kind that live in there and at times are generous and at times ... um ... playful. My computers over the years have done things that have had the builder testing the crud out of all the systems which separately work fine, but X don't like working with Y, though last week they was on outstanding terms. No driver changes, no ... nothing ... that could be diagnosed. A couple we just 'terminated', and a couple started playing nice again at some point before we'd got around to replacing them.

Something inside there clearly had changed, but we could never determine what it was.

Dang things drive me nuts at times.

Neil