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Low Framerate

Graphics issues like: bad framerates, weird colors, OpenGL errors etc. Bad graphics ar usually the result of bad graphics cards or drivers.
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In order to help you, we need to know a lot of information. Make sure to include answers to at least the following questions in your initial post.

- what OS (Windows Xp/Vista, Mac etc.) are you running?
- what FlightGear version do you use?
- what graphics card do you have?
- does the problem occur with any aircraft, at any airport?
- is there any output printed to the console (black window)?
- copy&paste your commandline (tick the "Show commandline box on the last page of FGRun or the "Others" section on the Mac launcher).
- please upload a screenshot of the problem.

If you experience FlightGear crashes, please report a bug using the issue tracker (can be also used for feature requests).
To run FlightGear on old computers with bad OpenGL support, please take a look at this wiki article. If you are seeing corrupted/broken textures, please see this article.

Note: If you did not get a reponse, even after 7 days, you may want to check out the FlightGear mailing lists to ask your question there.

Re: Low Framerate

Postby Richard » Fri Nov 08, 2019 5:08 pm

Robertfm wrote in Thu Nov 07, 2019 3:04 pm:This sort of thing just confuses me, everything I have read of GPU's and CPU' s suggest CPU usage is maxed out will affect GPU. But my CPU is operating in region between 30/40%. But my GPU only about 30% it makes no sense. Articles I've read say it should be 99 to 100%. The suggestions in the article point to a game one is playing.


If you're interested in flying then you only need 50fps; it is what the FAA require to certify a Level-D simulator. There is little point in having a frame rate higher than your monitor's refresh frequency (often 60hz) I usually fly with my frame rate locked at 30hz because consistency is more important than performance (for me).

So really I'd suggest that you should just be pleased that you're getting the sort of performance that your hardware is capable of providing.

Try flying over one of the busy areas (e.g. Paris, LFPG, LOWI) and see what happens to your GPU utilisation

I've been investigating FG performance for a few years now and can report that currently FlightGear can only use a single core to do most of the work of rendering and simulation; and thus on a system with 4 cores the maximum CPU % will be 25% (12.5% for a hyperthreaded 4 core CPU). So if you've got two cores and you're seeing 50% (or more) then that's almost as high as it could go - and there's little that can be done to improve this because FlightGear is using OSG which in turn uses OpenGL and the underlying GPU/driver architecture simply cannot be driven effectively from multiple threads (CPU cores).

I guess what I'm getting at is that the overall CPU and GPU utilisation as a single percentage value is potentially misleading - because it depends on how all the various stages of CPU and GPU processing (particularly GPU processing) have been added together to make a single percentage number. Also all of this is irrelevant if running at vsync.

Now maybe it's great that FSX can achieve 100+FPS; but really that's of little importance unless you're on a 120hz monitor.

Tell us what your monitor vsync rate is.
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Re: Low Framerate

Postby Robertfm » Fri Nov 08, 2019 7:45 pm

I checked out Vsync and it was on. I switched off and my frame rate short up from 60 to 125fpm. There are other settings like adaptive which I will try tomorrow. Again I have read up about Vsync and there appears to be a no size fits all opinion. For higher end games it is not recommended to have it on. If your monitors have a similar frequency then again there is no point in having it on. Anyway thanks for the advice. By the way my CPU has 6 cores and 12 threads

Forgot to mention before looking at graphics card and Vsync I had flown for 2 hours from day to night and the FR didn't drop at all. Go figure.
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Re: Low Framerate

Postby Robertfm » Sun Nov 10, 2019 12:52 pm

With Vsync set at fast I have had no noticeable drop from 60
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Re: Low Framerate

Postby Richard » Tue Nov 12, 2019 1:57 pm

Robertfm wrote in Fri Nov 08, 2019 7:45 pm:I checked out Vsync and it was on. I switched off and my frame rate short up from 60 to 125fpm. There are other settings like adaptive which I will try tomorrow. Again I have read up about Vsync and there appears to be a no size fits all opinion.


I don't specifically know about other games - but for FlightGear the only time that I am sure that turning vsync off is an advantage is with certain AMD cards that vsync the two cameras effectively giving a maximum of 30fps - otherwise there is no real advantage to be gained by turning vsync off.

The general reason for keeping vsync on is simply that there is little valid reason for updating the screen at a rate faster than the monitor is capable of displaying.

There may be specific cases where running at higher than vsync allows faster 'per frame' processing - however that would only apply to (badly) designed applications that lock the update logic to the screen refresh.
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Re: Low Framerate

Postby Robertfm » Tue Nov 12, 2019 2:34 pm

Thanks
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Re: Low Framerate

Postby RobAndrew » Tue Nov 12, 2019 10:33 pm

Sorry to jump in on the forum, but felt that I should take a chance of asking seeing as it's here...

I'm currently on a 2009 Macbook, with 8GB RAM a 2.26 Ghz Intel Core 2 Duo Processor and a NVIDIA GeForce 9400M, 256Mb Graphics card. With this setup I can get about 15FPS IF I'M LUCKY. It's usually around 8/9.
Is this normal for such a setup? I realize i'm not exactly running on a tower setup and it's an old laptop. I put 6 extra GB or RAM in, thinking it may help but i'm not sure it has. I am aware that it's not all down to the RAM though.

Again, sorry for butting in. I've just never really been told if my figures are correct with my spec, or if I need to investigate a bit.

I will say I run settings pretty high. 3D clouds, Mid vegetation. Pretty much everything apart from vegetation shadows.

THANK YOU!
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Re: Low Framerate

Postby legoboyvdlp » Tue Nov 12, 2019 10:35 pm

Are you using the overlay and urban shaders? They are very expensive by nature, since they are geometry shaders.
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Re: Low Framerate

Postby RobAndrew » Tue Nov 12, 2019 10:47 pm

well I usually use the custom shader, not sure which setting on "Urban" is higher or lower quality...as for the overlay shader, i've never even heard of it!
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Re: Low Framerate

Postby legoboyvdlp » Tue Nov 12, 2019 10:55 pm

They'll be in the custom shader settings; left is lower quality and right is higher quality. Overlay is the bottom one in the list and adds grass to airports.
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Re: Low Framerate

Postby V12 » Wed Nov 13, 2019 5:32 am

Switch off landmass, transtition, urban and overlay shaders.
Fly high, fly fast - fly Concorde !
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