Trees filling GPU processor to the max

[bkthunder]

I just did a test by placing a free camera (F-11 view) in the middle of a forest, and couldn't get past 45-46 FPS (no units moving, single player, no AI).

 

The GPU load was 99% all the time, CPU load about 15%.

This is with the following settings:

 

Visibility Ultra

MSAA 2x

Deferred shading ON

Shadows Default

 

everything else maxed out.

 

 

GTX1080 and i7 7700K at stock speed, 16 Gb DDR4.

 

It seems there is something with the highest LOD of the trees that really brings the system to its knees, and no amount of overclocking makes a difference.

 

 

Moving a few dozens feet higher, FPS go back to 60 (locked)

[BIGNEWY]

Hi

 

DCS will use as much of your gpu resource as it can, this is correct.

 

FPS being lower closer to the ground is due to more objects loading and is to be expected.

 

If your machine is struggling with it reduce settings to find the right balance for your preference.

[bkthunder]

The average GPU load in every other situation hardly exceeds 60%, so no, DCS is not filling my GPU all the time.

 

I did some more testing, and with terrain shadows set to FLAT, in the middle of the forest, there is hardly any noticeable performance drop. In fact the GPU load is ~75% with shadows on flat.

 

 

Some people were indicating MSAA as being the culprit for the low performance in highly dense forest areas, but in my case MSAA on or off didn't make much difference, while the shadows seems to have a tremendous impact.

 

 

Since I have a fairly modern PC (and also a common configuration i7 7700K + GTX 1080), I doubt it is a matter of bottlenecks or low specs.

 

DCS runs brilliantly considering the incredible gfx quality of 2.5, it would be great if performance regarding shadows and trees were improved to have a fully consistent experience :thumbup:

[sedenion]

The average GPU load in every other situation hardly exceeds 60%, so no, DCS is not filling my GPU all the time.

 

When CPU have more job to do, the GPU have to "wait" for CPU to finish its job; When CPU have less job to do, the GPU is free to loop at maximum speed... This is why your GPU load changes with CPU load.

 

To be correct, the GPU don't realy "wait" the CPU, but the draw-calls (the stage in the application loop where program calls DirectX functions to draw something) can be separated by more or less "time" between each frame (loop)...

 

The typical loop is:

 

1) Get input data (pure CPU job)

2) Update scene / IA / etc (pure CPU job)

3) Draw Scene (GPU job)

4) goto 1)

 

Considering this, depending the time CPU or GPU job takes within the loop, the load will be in favor of CPU job or GPU job...

[Lixma 06]

I can sort of confirm this - it's not so much the trees but the shadows on 'DEFAULT' setting that seems to be the culprit.

 

I've got a video on the way - sit tight.

[FragBum]

There are a number of aspects that will affect GPU usage, shadows, textures, MSAA, AF, what model you are using and what map, deferred shading or HDR, whether you enable or disable ASW, pixel density, VR vs 4K and all these settings interact and compete for GPU and CPU utilisation. I run 100% tree visibility and ultimately that's not the limiting feature for me for 45FPS stable in VR.

 

FWIW at stable 45FPS in VR my rig usually runs at 14 to 16% CPU (total) usage, ~9GB RAM and GPU 80 to 100%, although when it hits 100% micro freezes and other visual distortions occur, but I guess that's the limit right. :D

 

Sometimes some of the settings or at least the "levels" of these settings don't always bring much benefit verses the GPU/CPU utilisation they incur on the system.

 

System:

i7 5930 6/12 core @ 4.11GHz

32Gb DDR4 RAM @ 2.4GHz

1080Ti @ 1.974Ghz

Oculus Rift

Intel 750 Series 400GB NVMe PCIe SSD

 

YMMV. :thumbup::D

Edited February 17, 2018 by FragBum

[Lixma 06]

Here we go. Three clips all identical area and graphics settings (1080p, no AA, 'High' all round)

 

First is shadows 'OFF', then 'FLAT, then 'DEFAULT'.

 

 

 

As can be seen the OFF and FLAT settings are more or less identical in their GPU load (avg. 45%) whether just looking around or zoomed in.

 

On the other hand the DEFAULT setting averages at a higher GPU cost (75%) which is to be expected seeing that they're actual projections, but what is problematic is the massive spikes in GPU usage (95%+) the closer you get - e.g. when zoomed in to a tiny patch of ground with only about 10 trees visible. You would expect the GPU to be practically idling in a case like this....as if you were looking up at the sky.

 

Is it possible the 'DEFAULT' shadows are being rendered more and more detailed without limit the closer the proximity to the player? This might explain why a scene with only a couple of trees can bring, in my case, a 1070ti to its knees?

[Lixma 06]

Here's a comparison screenshot from the video showing the relative GPU loads while zoomed into the side of a hill with about 10 trees maximum on screen.

 

[El Bastardo]

DEFAULT terrain object shadows means it'll draw terrain object shadows according to the shadow setting, which in your case is high.

I'm not surprised to see a high GPU load in that case, since it has to render high quality shadows for every tree.

 

Furthermore, the level of details for the trees has been greatly improved with 2.5, meaning you have to get really close before the look of the trees stop to improve and effectively lower GPU load as you're zooming further in.

[FSKRipper]

Here's a comparison screenshot from the video showing the relative GPU loads while zoomed into the side of a hill with about 10 trees maximum on screen.

 

 

And in your 3rd picture you can clearly see trees casting shadows on other trees which is intended by the default setting. That's the main reason for high gpu load, was tested in the 2.5 optimal performance thread and is supposed to do exactly what it does...

[OttoPus]

Yep, there's indeed an issue with trees + ground shadows at "default".

[FSKRipper]

Yep, there's indeed an issue with trees + ground shadows at "default".

 

Maybe you got my post wrong.

 

The only issue is some thousand trees casting shadows to some other thousand trees. This is what this option should do and it does it perfectly. Taking 50% fps hit even on my 1080 is not suprising. The combination "high shadows" + default ground shadows + 80%++ Trees slider is meant for the absolute peak in computer hardware. Do it the same way as the other 99% of the people not in possession of hardware for 12000$ (including myself) and set the shadows to flat.

[OttoPus]

Nope, I'll explain better:

 

In this image you don't have "some thousand trees casting shadows to some other thousand trees", but the GPU taxi ( 30 fps ) happens anyway (Default shadows):

 

As a reference, here's the same place in the same mission with flat shadows (60 fps) :

Edited February 17, 2018 by OttoPus

[Lixma 06]

The only issue is some thousand trees casting shadows to some other thousand trees. This is what this option should do and it does it perfectly.

 

Then why is the GPU maxing out with only ten trees on-screen while using default shadows?

[FSKRipper]

Nope, I'll explain better:

 

In this image you don't have "some thousand trees casting shadows to some other thousand trees", but the GPU taxi ( 30 fps ) happens anyway (Default shadows):

 

As a reference, here's the same place in the same mission with flat shadows (60 fps) :

 

Then why is the GPU maxing out with only ten trees on-screen while using default shadows?

 

Sorry guys, I really hope you can work this out soon but this isn't reproducable in any way for me.

 

Shadows high, ground shadows default and I'm barely going below 50. And that my GPU is loaded at 92% doesn't suprise me. There are some dense areas (Kobuleti f.e.) where the count drops to 30fps but this has nothing to do with the tree LOD as it would have happened here also.

[sedenion]

There might be several good answere to "why Default shadow put GPU to max load even with few trees on screen ?".

 

The "Default" shadow use shadow mapping method, while "Flat" use another one (don't know which one exactly). And shadow mapping is a typical "per-pixel" shader computing, while the "Fat" is - I guess - more a "per-polygon"... Constraints and behaviors are not the same. One thing you can see at first glance, is that even if you are close to trees and see only 2 trees, the entire screen is concerned by the "shadow map testing", which mean, ALL PIXELS of the image are tested...

 

To know exactly "why", we must know the shadow mapping algorithm of DCS.

[Ramsay]

Then why is the GPU maxing out with only ten trees on-screen while using default shadows?

 

Because you are surrounded by trees that cast shadows on shadows and that cast a shadow where you stand 'now' or where you 'might' look next.

 

As said, the terrain 'default' shadow setting is NOT DCS's default, it's yours - whatever you've set for cockpit shadows, etc.

 

The option lets you use high quality shadows for your aircraft/cockpit and flat shadows for the many close terrain objects (reducing the performance hit).

 

Sideslip's post covers 2.5's GFX Settings and GPU Impact better.

[Lixma 06]

Because you are surrounded by trees that cast shadows on shadows and that cast a shadow where you stand 'now' or where you 'might' look next.

 

Watch my video.

 

FPS goes down and the GPU load goes up when there are less trees being rendered on screen. This is backwards.

 

The DEFAULT shadows are being rendered with more or less detail depending on distance to the player - that's obvious enough.

 

But when you can zoom in to just a handful of trees and bring your GPU to its knees....well that suggests the DEFAULT process of rendering shadows is just a bit over-enthusiastic at close range.

[Sideslip]

Watch my video.

 

FPS goes down and the GPU load goes up when there are less trees being rendered on screen. This is backwards.

 

The DEFAULT shadows are being rendered with more or less detail depending on distance to the player - that's obvious enough.

 

But when you can zoom in to just a handful of trees and bring your GPU to its knees....well that suggests the DEFAULT process of rendering shadows is just a bit over-enthusiastic at close range.

 

I don't think you fully understand whats going on.

 

Problems with your observations:

 

1: Just because you don't see the other trees, doesn't mean their shadows aren't being computed. Yes you can only "see" a couple trees, but there are almost certainly 10-20 more hidden at the top of your picture.

 

2: If you have grass enabled it is a big load on the GPU. Grass it not drawn beyond a very very short distance. When you bring the camera in tight like that, your GPU is working to draw that grass that it wasn't drawing when there were hundreds of trees on the screen. So tree/shadow workload decreased and grass workload increased. Result is no change.

 

3: All tree shadows are flat after a certain distance, and that is a very short distance. Sure you removed 90% of trees from view, but the 10% that are left are the only ones that had high quality shadows in the first place.

 

4: Zooming in increases the distance at which things are drawn. Zooming in on distant trees increases their quality and the shadow quality.

 

5: Shadow resolution dynamically gets higher the closer they are. Zooming in has the same effect.

 

 

Shadows in any game have always been demanding, DCS is no different. Set the terrain shadows to flat and it is no longer a problem. And why do you insist on using high shadows and then complain about the performance? There is are settings for a reason. If you aren't happy with the performance, lower the settings. This is far from a bug.

 

As per my pre-existing thread, if you are hell-bent on using default terrain shadows, using high quality requires a lot of horse power.

 

Off | Flat | Low | Medium | High:

 

 

P.S. Showing CPU and GPU usage without framerate is a little ambiguous. GPU load can remain the same as framerates increase signifying a reduction in overall load per frame.

Edited February 18, 2018 by Sideslip