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OB: 1st flight fine, second has large FPS loss


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I've tried everything I can think of at this point and I have been testing this with the same simple mission in Normandy using the Mig-29A. The first flight is really nice, smooth, down low, over cities, and everything stays in the mid 40 FPS range. Once I get back out and hit fly again though the next flight has a significant FPS drop (down into the teens) with stuttering.

 

I've deleted the saved games fxo and meta shaders folders and tried mess around with in game and nVidia settings but the problem persists unless I restart my whole system - and again I only get one good flight in. Does anyone have any advice?? I already have a paging file set up 32gb of virtual.


Edited by Azazel

My Rig: EVGA GTX 1070 x 2 | EVGA x58 SLI classified | i7 X 990 CPU | 24 GB RAM | Windows 10 Home 64 bit| Track IR Pro | CH Fighter Stick | CH Throttle | CH Pro Pedals |

 

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OB is reported to suffer from memory leaks . Update may fix this week .

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Thanks for the reply. I was hesitant to call it that, but it certainly seems like that might be the culprit on my end.

My Rig: EVGA GTX 1070 x 2 | EVGA x58 SLI classified | i7 X 990 CPU | 24 GB RAM | Windows 10 Home 64 bit| Track IR Pro | CH Fighter Stick | CH Throttle | CH Pro Pedals |

 

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Post OB update and I still have this same issue. I just reformatted my computer and now have everything on an m.2 drive. Reinstalled nVidia drivers, etc. Same problem as before though - 1st flight in the sim has great frames down low, hit fly again and that flight has reduced fps and stutters.

My Rig: EVGA GTX 1070 x 2 | EVGA x58 SLI classified | i7 X 990 CPU | 24 GB RAM | Windows 10 Home 64 bit| Track IR Pro | CH Fighter Stick | CH Throttle | CH Pro Pedals |

 

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Post OB update and I still have this same issue. I just reformatted my computer and now have everything on an m.2 drive. Reinstalled nVidia drivers, etc. Same problem as before though - 1st flight in the sim has great frames down low, hit fly again and that flight has reduced fps and stutters.

 

i have reported this behaviour years ago. my theory back then was, that it only really showed for people with 8 gbyte of ram or less, but that it would still affect every system, only to a much lesser extend.

i confirmed my findings on a different machine with 16 gbyte of ram and more vram and the reduction in fps was harder to trigger and fps loss was way less, but the problem was still there.

it's not a memory leak in the classical sense, where ram usage grows constantly until it crashes, but it seems to be an issue with memory management, where some types of terrain data of last flight gets not cleared completely resulting in bigger memory foodprint with each flight. i assume it is terrain related because, i could quickly trigger it by changing the seasonal textures in caucaus in the ME and seeing ram usage rise with every change.

 

one of the moderators took note of my findings, but i don't think that anything came from it. i just tend to always restart DCS when my memory got filled up that way (at least on smaller missions it would need multiple restarts to fill the memory).

 

you can find my original thread in this forum section. i did quite a lot of testing on it.

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could your problem be related to this? monitor your vRam usage and see if there is a relation between your fps hit and vRam foodprint.

 

Suggestions and help is appreciated obviously! thanks!

 

***

 

I did some more testing and while Drag80's solution did not help (alt-tab when performance degrades), i tested to disable "run fullscreen" in options and also disabled the steam overlay:

I did not test it scientifically, but with these changes it seemed that it took longer for the degredation to kick in and it felt as if in the degraded state, i might had some fps more than before. This could have been a placebo though.

 

As the easiest way to get the degredation was changing the season in mission editor, i tested the seasons in caucassus, while monitoring the Vram usage.

I can now say for sure, that every season other than summer seems to load textures on top of summer textures, so even when directly loading into a caucassus autumn mission i would have over 8gb (!) of vram usage ( reported from the dcs system monitor).

Changing the season and loading again would add more usage on top, so i could end up with 15gb of Vram reported by DCS just with me in a mustang doing a ramp start.

 

Closing DCS, starting again and loading into a mission in summer (which seems to be the base texture set) DCS would only report 4gb Vram used.

 

Even though my GPU has only 4gb, i could get good performance even when reported Vram was above 8gb, so i assume that DCS already does some Vram management wizadry in the background.

 

While i could not directly link the state of degraded performance to Vram usage, i still think that they are related.

Even though i could sometimes get the "good" performance with over 8gb reported on first loading in, when the performance degredation hit reported Vram usage was always higher than before the hit.

Example:

 

-mission A. summer caucassus:

#1load: ~60fps ~4200mb Vram

#2load: ~60fps ~4200mb Vram

#3load: ~30fps ~4400mb Vram

-restarting dcs

-mission B. autumn caucassus:

#1load: ~60fps ~8000mb Vram

#2load: ~30fps ~8200mb Vram

(mission A and B are nearly identical, only real difference was the season)

 

My theory at this point:

- Caucassus season textures have a huge Vram foodprint, because seasons other than summer get their textures loaded on top of base set.

- DCS does good work in managing/swapping Vram in the background, allowing even 4gb Gpus to pump out good performance when more than double their Vram sieze gets allocated for Vram data.

- Sometimes the swapping somehow clogs the pipeline, with higher Vram usage meaning higher change of failure

- DCS always adds Vram allocation in use, but never seems to de-allocate Vram. Only way to reset Vram allocation back to "sane" levels is restarting the game.

 

BIGNEWY, can you make a report to the team, based on this assumption, or is it not "scientific" enough?

Again, i'm not so much concerned with the performance on my old machine, but could reproduce this behaviour on a different 16gb/8gbVram pc, so it should be of general concern!

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Thanks for the reply. That certainly fits my situation it seems. I am waiting on a new video card (GTX 1070) so with any luck that will fix my issue. For the time being, shutting down DCS and loading it back up will have to suffice. At least with the new M.2 drive everything certainly loads much faster now.

My Rig: EVGA GTX 1070 x 2 | EVGA x58 SLI classified | i7 X 990 CPU | 24 GB RAM | Windows 10 Home 64 bit| Track IR Pro | CH Fighter Stick | CH Throttle | CH Pro Pedals |

 

[sIGPIC][/sIGPIC]

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