Massive FPS drops when memory required from GPU is more than the VRAM

Bug Reporting Hub Resolved
1

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Are you using Developer Mode or made changes in it?

Using it just for the FPS display

Brief description of the issue:

With DX12 and DLSS, performance is very good in my rig (i5-12600k, RTX2070S, 32 GB Ram, running at 1440p). But sometimes I get huge FPS drops (from 40 to 15) and I think itĀ“s because the memory allocated to the GPU is higher than the available VRAM (8 Gb in my case). It happens normally when looking at certain parts of the scenary, or in the cabin. For example, with the Fenix A320, when I look at the back of the seat.

Provide Screenshot(s)/video(s) of the issue encountered:

vram1

By the way, thatĀ“s just an example to show how GPU time goes through the roof. In that particular case the overall FPS was still acceptable, but in other cases it goes really low, like 14 or 20

Detailed steps to reproduce the issue encountered:

Normally happens when flying around photogrammetry areas with complex addons, like the Fenix A320

PC specs and/or peripheral set up if relevant:

i5-12600k, RTX2070S, 32 GB Ram, running at 1440p

Are you using DX12?

yes

Are you using DLSS?

yes

Are you using the multi monitor feature?

no

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OPā€™s steps to reproduce it?

Provide extra information to complete the original description of the issue:

Are you using DX12?

Are you using DLSS?

If relevant, provide additional screenshots/video:

2

Youā€™re not the first Iā€™ve seen with this issue so Iā€™m upvoting it. Once a game over-commits beyond available VRAM then it starts tapping into shared system RAM which is really slow.

5 Likes
3

If you are on PC and using Windows pagefile that could be the pagefile size being adjusted to increase it, in case you have set size to auto or to a range with min and max values. I also saw that behaviour prior to beta. The best to avoid it is to set a fixed size (same min value as max value), whatever the size you want or you need to use for your system.

Cheers

5

But the pagefile is only for RAM, right? I am talking about VRAM. Normally it has nothing to do as far as I know.

6

Thatā€™s right the pagefile generally only grows when the commit charge is reaching the commit limit (if the pagefile maximum size hasnā€™t been reached).

7

When the VRAM is not enough, the graphics card can also pick a portion of the computerā€™s RAM to serve as its own video memory. Then portions on both RAM and VRAM can be ā€œsitting on the pagefileā€ so to speak. Even if game now uses a big size of RAM Windows still books a huge pagefile size for the game process (easily 20-25Gb if you have 32Gb of RAM). Normally not all that size is used, but itĀ“s still booked.

Cheers

2 Likes
8

You can track page file usage and commit charge using windows performance counters. I even have them in my Afterburner on-screen display/graph. Might as well add shared GPU memory usage in there as well.

1 Like
9

So if I want to fix a pagefile size to make sure itĀ“s big enough, what size should I allocate? I have 32 Gb RAM

10

Same issue is happening with me. Curious to know if the pagefile does solve it. I donā€™t have the issue with DX11.

1 Like
11

Ok, surprisedā€¦ apparently fixing the pagefile size indeed helps. ItĀ“s not completely solving the problem, I still get times when the VRAM to allocate surpasses the GPU memory, and then I get the drop of FPS. But much less than before and seems smoother. I did one test only, though.

12

The fps drops you see are due to disk speeds being normally lower than RAM speeds. Data still needs to be transferred from one side to the other. This is improved with modern PCI-E disks. But with SSDs (my case) you are still very limited by disk and thatĀ“s why I always try to avoid pagefile as much as I can, but in this game is almost mandatory.

The size depends on the quality settings you have and how heavy the scenery you are loading is. Also take into account that there are still some random memory errors in game, so you may face sporadic CTDs.

In my case I have buildings photogrametry OFF and with my 11Gb of VRAM and 32 Gb of RAM I normally use a fixed pagefile size of 8Gb or 16Gb with no issues. I have seen RAM usage going up to 80% yesterday with beta under the 8Gb setting and game runs pretty stable, so until I enable photogrametry again I will leave it like that. I only had a CTD when I forced my system on purpose trying to load a very heavy area at max settings to force such a CTD caused by memory.

Cheers

1 Like
13

My scenario:
Always taking off from KLAX (ORBX)to the east using AI Pilot, C172 G1000 with PFD and MFD popped out. 9900K, RTX 2080Ti, HT off
DLSS set to quality, Sync off, High-End profile setting without custom changes

DX11: I am CPU limited with 25 to 30 fps on ground, 40 fps after crossing opposite threshold, GPU usage 20 to 45, with mid 25, CPU usage 80 to 100

DX12: I am GPU limited with 27 to 32 fps on ground, 35 fps after crossing opposite threshold, GPU usage 15 to 25, with mid 20 but spikes up to 50, CPU usage 60 to 70

I cannot understand the GPU limitation with DX12 with the GPU always yellow and seeming to be tied to CPU which is also yellow. Both ms values are basically the same. I guess it might have to do with VRAM. With DX12 my 11GB of VRAM are used up to 9.5GB and some more extra VRAM shows up on task manager (the virtual one, whatever). Maybe this is why it shows GPU limitedā€¦ who knows. (DX11: about 5 GB VRAM usage)

Using DX11 might stress out the CPU more yet the GPU seems not to be bound to the CPU showing steady green. So for my setup I guess upgrading to 12700K and using DX11 would be the best option.

I also noted that the ā€žpop out penaltyā€œ with DX11 seems to have disappeared. Until SU10 I had to use DX12 in order to be able to use pop out panels.

All this seems a bit complicatedā€¦ā€¦

14

image
image1920Ɨ1055 93.5 KB

Uploading here because I thought itā€™s suitable, correct me if wrong :slight_smile:
Common effect for me after exceeding GPU memory; happens in diverse places such as KLAS (as shown here), YSBK, KPDX, EGKK, OMSJ, and more. FPS varies from 8-25 in different locations and times. (Here is 20.9 fps - sorry for the cut screenshot - but last night it averaged 7-8 fps at the same location, with exaggerated terrain, glitched artifacts, and gigantic trees all-in-one)

1 Like
15

I have the same issue.
My FPS occasionally drop from 40 to 12 when VRAM required is higher then VRAM available.

Screenshot (821)
Screenshot (821)1920Ɨ1080 127 KB

4 Likes
16

Nope.

Thatā€˜s only true for ā€žshared memoryā€œ GPUs and there all GPU data sits in the ā€žnormal system RAMā€œ in the first place.

17

100% agree (although I have seen others dispute that)

Also, there is a registry setting that Clears the Pagefile when you shut down, so on a Restart, it is cleared out. Really for Security reasons, but it does seem to help starting off ā€œwith a clean bowlā€

John "The Biscuit" Cage: I like a fresh bowl.)

18

I hope the devs. donā€™t read this thread, and start working on further reducing GPU usage. I for one am happy to see users with high GPU usage. As long as it doesnā€™t go over 24GB Iā€™m happy. :stuck_out_tongue_winking_eye:

7 Likes
19

Same problem

20

Can u check if ur Sim is performing more stable und with higher fps during discover flights? For some reason my Sim is performing well in discover 90% GPU usage and 60 fps but during free flight with the same plane I just get 30-40 FPS, stutter and just 50% GPU usage

21

Well for the hundreds of us who donā€™t have DX12 working properly, I do hope the devs fix it.

1 Like