Sign in to follow this  
honanhal

Dumb question about AI performance

Recommended Posts

Hi all,

 

Very basic question here. I'm using DX10 with Steve's fixer but had this same effect with DX9, so don't think it's relevant.

 

I've always been a big of an AI airliner traffic but, willing to tolerate poor performance for absurd amounts of planes. (I'm using a custom mix of FSX native and FS9 models where FSX ones aren't available). Usually I run airliner traffic at 100% but limit it to 100 planes with the traffic optimizer.

 

In the past, that usually meant a visible performance hit just from those AI aircraft existing in the sim, whether or not they were actually in sight. So since I lock frames at 1/2 Vsync it would drop e.g. to 20 or so in busy airspace with a complex add on aircraft. Having recently upgraded to a 6700k and 1070, I'm getting locked 30 dpa almost everywhere even with 100 aircraft present in the sim. With one exception:

 

Even with the default Trike, if there are large numbers (more than 30, say) of AI planes in sight at an airport the frame rate tumbles to the teens. If i move the view away so they're not visible it shoots back to 30. My question: is this normal and expected behavior, or is it a symptom of some problem (e.g. missing effect files, messed up textures etc)? Could it be related to my running DSR?

 

I've run the alpha channel fixer to rule that issue out, and I've resized 4K textures to 1024 (more to save VAS than anything). I checked for missing textures with FSX's debugger and found a handful but fixed them, and it made zero performance difference.

 

I'm willing to take the hit, which is only a issue at certain airports with tightly packed gates (e.g. Sydney, Shanghai), but I'm genuinely curious and figure some of the experts here would immediately know the answer. Thanks!

 

James

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Hi all,

 

Very basic question here. I'm using DX10 with Steve's fixer but had this same effect with DX9, so don't think it's relevant.

 

I've always been a big of an AI airliner traffic but, willing to tolerate poor performance for absurd amounts of planes. (I'm using a custom mix of FSX native and FS9 models where FSX ones aren't available). Usually I run airliner traffic at 100% but limit it to 100 planes with the traffic optimizer.

 

In the past, that usually meant a visible performance hit just from those AI aircraft existing in the sim, whether or not they were actually in sight. So since I lock frames at 1/2 Vsync it would drop e.g. to 20 or so in busy airspace with a complex add on aircraft. Having recently upgraded to a 6700k and 1070, I'm getting locked 30 dpa almost everywhere even with 100 aircraft present in the sim. With one exception:

 

Even with the default Trike, if there are large numbers (more than 30, say) of AI planes in sight at an airport the frame rate tumbles to the teens. If i move the view away so they're not visible it shoots back to 30. My question: is this normal and expected behavior, or is it a symptom of some problem (e.g. missing effect files, messed up textures etc)? Could it be related to my running DSR?

 

I've run the alpha channel fixer to rule that issue out, and I've resized 4K textures to 1024 (more to save VAS than anything). I checked for missing textures with FSX's debugger and found a handful but fixed them, and it made zero performance difference.

 

I'm willing to take the hit, which is only a issue at certain airports with tightly packed gates (e.g. Sydney, Shanghai), but I'm genuinely curious and figure some of the experts here would immediately know the answer. Thanks!

 

James

Hi,

From what I understand, your problem is FSX:SE gets lower FPS when the airport +AI traffic is insight, when you turn away the FPS jumps again?

If that is what you meant, then it happens the same to me and I find it normal (or I'm having problem too if it's not normal).

When I look outside from VC, airport terminals + AI traffics insight, the FPS drop to 15-25. When I change my view to FMC only (I use chaseplane) in VC, I get +40FPS. So it should be how the computer hardware load the texture and autogen....

 

Hoang Le

Share this post


Link to post
Share on other sites

FSX native or not, simple or not, all AI models will clog the video card as their polygons, textures and animations require considerable effort to be turned into objects that can be shown on the monitor.

 

A good measure to judge the impact of a model in FSX is a draw call, which roughly indicates the video processing effort required for a model. User aircraft will command anywhere from 100 (default aircraft) to more than 600 (a certain payware three-engined Boeing) draw calls. Older AI aircraft (e.g. AIA) may have 30 or so draw calls while current-gen AI models have 70 (or more) draw calls. Now take an average of 50 draw calls per model, multiply this by 50 models drawn on screen and the result is a huge additional strain on video card resources. Throw the draw call requirements of the scenery, terrain, autogen and clouds into the mix and you'll be amazed that the graphics engine manages to output more than 15 FPS at huge airports at all.

 

And then there's the bandwidth bottleneck between the CPU, RAM and video card. The transfer rates you see for your RAM, PCIExpress bus and video RAM are all peak values and do not reflect the real bandwith obtained with a huge amount of parallel read and write requirements. High clock speeds for the CPU, RAM and VRAM help somewhat because the memory is refreshed (and thus accessed) more frequently, but the only permanent solution for better framerates is actually decreasing the peak draw call demand for a scene by whatever means you think will work for you. Some prefer no autogen, some turn down AI, some do not use high detail user aircraft and some will settle for the default airports.

 

My solution is simple AI models, less variety in autogen, simpler car traffic, standard detail radius, keeping a close eye on user aircraft performance, using AI Traffic Manager and staying away from New York. This place is framerate hell!

Share this post


Link to post
Share on other sites

I think Bjoern summed up FSX performance pretty nicely.  A computer with a very modern and very fast CPU, very fast RAM that has low timings (speed alone is not the sole key to RAM performance), a video card with fast RAM, and everything with the highest data bandwidths possible will allow you to increase the amount of AI traffic, autogen, detail radius, use detailed add-on scenery, and fly a highly detailed aircraft.  The rest of us, especially those of us with old Core2Quad systems (that's me), have to make sacrifices.

Share this post


Link to post
Share on other sites

Thanks, guys. So what I'm hearing is yes, this is normal and expected behavior.

 

Good to know, still just seems strange that I can literally throw anything else at FSX (autogen, heavy airport scenery, Vector, etc.) and it doesn't dip below 30 frames in the Trike, but AI in the visible frame not only causes it to dip but tanks the frame rate. Oh well!

 

Stans, I guess I didn't make it clear: I just upgraded and have all those things! Performance even with e.g. the PMDG 777 is butter smooth in literally every other situation. Heavy overcast over Europe that would have put my old rig at about 10 fps? 30 frames locked, nary a stutter. I don't have to make any other sacrifices! It is literally only AI on screen that can bring down the performance on my new rig.

 

James

Share this post


Link to post
Share on other sites

I'm pretty much an FSX-SE novice but I can tell you that in FS9, if you have an AI traffic file with missing aircraft then it will produce the kind of effect you're describing. The AI file is looking for a model that it's being called to produce and it can't find it...  Let's say that you are flying into KSEA and there's a traffic file that is looking for the FAIB 737-900 with an Alaska texture. If the entry in aircraft.cfg file is missing that particular paint, or if the textures for it are missing, your sysem will keep cycling through all the AI trying to find it.

 

I'm not sure if this is true for FSX but it can give you a similar performance hit in FS9 and if you find the culprit and fix it, you will see a dramatic improvement in FPS. Have you run AIFP3 or some other similar utility to see if you have any missing aircraft or textures? It might be worth a try. Then you can either find the missing repaint, or fix the cfg file or decompile the AI file and substitute another aircraft. Either way, in FS9 at least, the results will be very noticeable

Cheers

Ian

Share this post


Link to post
Share on other sites

Ian, thanks. This is exactly the kind of thing I was wondering about. I'll see if I can figure out if there's a missing aircraft/texture. Any recommendation on the best way to do that? Does AIFP have the features to track that down?

 

Thanks,

James

Share this post


Link to post
Share on other sites

You could put ShowMissingTextureAlert=1 in the scenery section of your FSX config file and it will tell you if there's any missing textures on planes.

Share this post


Link to post
Share on other sites

I'm not familiar with Jeff's fix but it sounds like it may be worth a try. AIFP does have a function that will identify a number of needed fixes in an AI file.

 

You can also try putting all your AI files in a seperate folder and then activate a few of them at a time. When the problem occurs, you've found your culprit. Decompile, substitute a different aircraft for the missing one and you should be good to go

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this