Strange FPS behaviour

[SkateZilla]

from my knowledge, if DCS simulates correctly G Forces and Blackouts,

 

As you bank and pull higher Gs, input is slowed down and eventually cut off (simulating a blackout).

[TZeer]

Yeah, but I don't see the point in the GPU/CPU pulling a "blackout" :smilewink:

 

Those effect's are ingame. It has no influence on how the hardware should behave.

 

When you get the drop depends on how hard and how long you hold the turn. I was able to provoke the drop even at 2,5 G. Not very much, but I was holding the turn for a short moment then.

 

Or I can just break left/right and pull a 4,5 G turn instantly and get the drop.

 

 

If anyone have some spare time to help me test something out I would appreciate it.

 

I'm looking for people with either a AMD 7970 or Nvidia GTX 680 card, and high end i5/i7 CPU.

 

Thanks

[SkateZilla]

Loading and keeping the objects/Scenery for 360° FoV because your constantly rotating.?

 

I've been smooth (with exception of some of the Arty Strikes in some missions), And I've actually just found a bottleneck in my system (Cheapo PSU doesnt have Single 12v Rail, so it starves my GPU of Power under heavy load).

[TZeer]

Loading and keeping the objects/Scenery for 360° FoV because your constantly rotating.?

 

I've been smooth (with exception of some of the Arty Strikes in some missions), And I've actually just found a bottleneck in my system (Cheapo PSU doesnt have Single 12v Rail, so it starves my GPU of Power under heavy load).

 

VRAM is never maxed out.

Doesn't matter if I use high or low detail textures.

And doesn't matter if I do it in populated area or flat boring landscape.

 

And I just tested in the SU-25T, I can turn and jink that aircraft all over the place without getting the same effect. Rock solid 80-90 FPS over Tiblisi with Kuky's high.lua mod.

[SkateZilla]

Test the F-15C. That would rule out AFMs if it stays smooth,

 

then the only common between A-10 and F-15C if it persists is the 6DoF Cockpits.

 

The a-10C's pit has a mess of systems scripted and running that the SU25 doesnt.

[Vlerkies]

 

Reason for the FPS drops turned out to be me pulling a tight turn!!!! YES!!

 

TZeer, thanks for your testing efforts.

 

I note you say you turned textures up and down and vram is not maxed + no diff between the two.

 

As for textures, would the resulting fps drop not be more a function of visibility range and scenes, as well as the clutter/bush preload range? (loading more while turning, compounded but tighter/faster turn)

 

btw: my vram tends to load along at 1.3, occasionally going up to above 1.6 but not for long.

 

Also cockpit res which controls mirrors/sensor maps/images?

 

from manual.

Note: If you wish to increase frame rates, the most import graphics settings to adjust lower are VISB RANGE, WATER, and SHADOWS.

 

So does cranking these settings down stop the drop

Edited February 11, 2013 by Vlerkies

[Vlerkies]

 

Have a fellow squadron member that have almost identical system as me, i7 3820. But instead of GTX 580, he is running GTX 680. Since this is a Sandy Bridge-E CPU we are still running

PCI-E 2.0 and not PCI-E 3.0 as Ivy Bridge. This way we can at least rule out the PCI-E lanes as the reason.

 

Have not been able to do the PCI-E 2.0 vs 3.0 test.

 

When shopping for GPU to make my sim run better I was given this answer on PCI-e 2 vs 3 mobo's

http://forums.eagle.ru/showpost.php?p=1632317&postcount=29

 

If anyone have some spare time to help me test something out I would appreciate it.

 

I'm looking for people with either a AMD 7970 or Nvidia GTX 680 card, and high end i5/i7 CPU.

 

Thanks

 

Will gladly help if you need a few more options.

Edited February 11, 2013 by Vlerkies

[TZeer]

Test the F-15C. That would rule out AFMs if it stays smooth,

 

then the only common between A-10 and F-15C if it persists is the 6DoF Cockpits.

 

The a-10C's pit has a mess of systems scripted and running that the SU25 doesnt.

 

Will do :)

 

 

As for textures, would the resulting fps drop not be more a function of visibility range and scenes, as well as the clutter/bush preload range? (loading more while turning, compounded but tighter/faster turn)

 

If it was, it should have been happening when I did the same thing with the SU-25. Which it didn't.

 

Also cockpit res which controls mirrors/sensor maps/images?

 

from manual.

Note: If you wish to increase frame rates, the most import graphics settings to adjust lower are VISB RANGE, WATER, and SHADOWS.

 

So does cranking these settings down stop the drop

 

I don't have mirrors activated.

 

Cockpit MFD resolution is at 512.

 

Shadows are high, In my earlier tests it had no effect on my FPS on my setup.

 

Water I took down to low, due to some strange FPS drops that came into play. My first post in this thread I show some screenshots where you don't see much difference, but the FPS drop is very noticeable. Reducing water to low, almost reduced that drop to nothing.

 

Visible Range, yes, that has a very big impact on FPS. But, reason I kept testing was due to GPU usage and CPU usage going down when the FPS was going down. If you read my earlier tests you can see screnshots of my CPU and GPU usage during these tests.

I even took away my overclock in the scenes where I had the least FPS. Removing almost 1 GHz of CPU power did nothing to my FPS.

 

 

 

 

I was able to do some tests with a fellow squadron pilot last night. He had single GTX 680. We where unable to provoke the same GPU usage drop on his machine. So this might be a SLI issue. Would need another test first.

 

Vlerkies sending you a PM :)

[TZeer]

BREAKTHROUGH!!

 

I can now start and stop the FPS drop at will.

 

It looks to be tied to the FM of the A-10C.

 

Every time I drop below 263 knots +/- a few knots depending on load-out or altitude (This one I havent figured out yet). The CPU usage and GPU usage drops. Get above it again and the GPU usage and CPU usage goes up again.

 

I have not been able to reproduce it on a single 580 GTX. This can either mean it only happen to SLI setups. Or my graphic card is not powerful enough. Even with the drop in CPU usage and GPU usage on a SLI setup, the load will still be enough to tax my GPU at 100% and it will restrict the performance.

[EtherealN]

Could you give me a track where you do this? I've seen similar things before A-10C public beta, want to see if it's the same thing.

[Vlerkies]

Looking at your first cockpit screenshots you posted though, its maybe not as clear as that.

 

Airspeed/FPS (4 cockpit screenies)

 

274/87

271/58

270/96

266/52

 

edit: actually 266 airspeed was the lowest fps, maybe!

Edited February 11, 2013 by Vlerkies

[TZeer]

Here is the track for the GPU/CPU usage drop.

 

Also linking the performance screens.

 

 

 

 

 

 

Looking at your first cockpit screenshots you posted though, its maybe not as clear as that.

 

Airspeed/FPS (4 cockpit screenies)

 

274/87

271/58

270/96

266/52

 

edit: actually 266 airspeed was the lowest fps, maybe!

 

 

That behavior I have not been able to reproduce yet, haven't tried that hard yet either. But I suspect it's tied to something else.

Test.trk

[TZeer]

Also, activating your flood lights in the cockpit kills the FPS by ~50FPS

 

Takes the FPS from 120-130 and down to 70-80.

 

But if the plane is going slower then ~260knots, the FPS is already down to ~60FPS and you get no further drop by activating the floodlights.

[SkateZilla]

only obvious thing linked to 270~knots is the heatblur.

 

512 MFDs vs 256 do have an Impact.

 

PCIe2.0 16 Lanes vs PCIe3.0 16 Lanes is irrelevant, no Single GPU uses the Max Bandwidth of the PCI2.0 x16 Slots yet,.

[Vlerkies]

Attached from my rig running the track you posted.

[TZeer]

More testing.

 

With speed lower then ~260 knots.

 

The drop in FPS goes away if I go external view and zoom out. When I cross a certain distance everything goes up.

 

When I zoom back in, everything goes down. Going from 130-140 FPS and smack down to 59-60 FPS.

 

 

I don't think it is related to the blur, as the blur will come in effect as soon as you go full throttle. I was going full throttle from 180 knots, and the FPS did not go back up until I crossed the ~260 knot speed.

Edited February 11, 2013 by TZeer

[SkateZilla]

heatBlur Shader is Disabled at 260~knots,

 

Anything below that, and it's ON, but throttle dependant (and Options ON/OFF Dependant).

[TZeer]

Spot on SkateZilla!!

 

Just tested it and your right. Taking off the heat blur effect removes the problem.

 

Now the question is, why does the heat blur effect reduce GPU and CPU usage?

 

Btw, did not see this behavior on the SU-25T.

 

Is the bandwith of the GPU at it's limit? Memory controller full?

[SkateZilla]

no idea...

 

possible bug or leak...

 

Maybe someone from ED can confirm.

 

I run smoothly with it all on, but I'll turn it off to see what happens.

[TZeer]

Updated first post with current findings and status.

[ralfidude]

Nice finds, I have te GTX 690 so i will turn my water and heat blur down and off.

[TZeer]

Let me know how it goes. I have a friend that has the same card, but we are unable to get it working properly, not just in DCS, but other games as well. His GPU's will just not activate properly. It's like something is telling them to perform at maximum 40-50%.

 

What kinda driver version are you using for the 690?

[SkateZilla]

that's Drivers,

 

You Need nVidia to make a DCS Profile for Scaling between multiple GPUs

[TZeer]

Have it working perfectly with my 2x580GTX in SLI. But I have read there are alot of people struggling to get their 690 working properly, even in 3DMark.

[ralfidude]

Yeah the 690 under most recent drivers are causing me pains in certain places. I check my GPU strength, and they don't distribute the wealth between the GPUs. So one just maxes out, and the other is just chillin idle. It's annoying. In other instances the GPU sits at a very low % and the CPU is not even pulling up all it's might but the game is laggy for me. It's weird...

 

 

As far as FC3 goes, even with water at high (Though there is a visual glitch where water on rivers when flying low appear to be 100 feet below the surface), I get a good 100 FPS. But when certain things are happening or as you mentioned, just looking at one particular area (even if it's an area that has absolutely NOTHING going on, and is empty all the way to the end of the map) I will drop down to 30.... from 100 to 30.... I mean what is that?

 

 

I'm also told that you essentially render ALL the things that are happening regardless if you are looking there or not. So anybody using a CBU 87 in DCS world, will cause EVERYBODY on the server to drop their frame rate to absolute crap regardless of where they are or where they are looking.

 

That's not right, but we know it's the game.

 

I love this sim, and all that, but you really have to consider what they were thinking making it run on ONE CORE and putting only SOUND on the second CORE.... I'm flabbergasted by that.

 

 

PS: The best fun is to go with the SU-25, and equip all cluster bombs, then roll up on an area, and just release them all in a ripple effect.

 

Watch the server list drop by 50%.