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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.
Forum rules
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 Icecode GL » Thu Nov 07, 2019 2:59 pm

Forgive me if my paraphrase is wrong, 'so you are saying it's the Sim not my system.' So why did I initially receive 120+fpm in game. It has settled back to 60 but drops to less than 30 after several hours flying.


No idea to be honest. I meant to say that not having 100% GPU usage isn't a sign of hardware/system/config issues.
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Re: Low Framerate

Postby Robertfm » 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.

At the moment I am getting 55/60 fpm, will see how that pans out later.
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Re: Low Framerate

Postby wkitty42 » Thu Nov 07, 2019 3:38 pm

SurferTim wrote in Thu Nov 07, 2019 11:44 am:@V12: Off topic, but I thought you night know where does one post changes/additions to the nav.dat file? Casablanca Morocco is missing an important navaid, which I have added to my nav.dat.

instead of editing nav.dat, put the fixed section in a file in your custom scenery directory in NavData/nav/blah.dat

eg: ~/myflightgear/mySceneryOverrides/NavData/nav/LIRN.dat

in my case, the above fixes the missing ILS-cat-I entry for LIRN RWY06...

just like NavData/apt, the files but be complete and represent the entire location... they are used as complete overrides in the database instead of the data in apt.dat and nav.dat...

~/myflightgear/mySceneryOverrides/NavData/nav/LIRN.dat
Code: Select all
810 Version - data cycle 2013.10, build 20131334, metadata NavXP810.  Copyright (c) 2013, Robin A. Peel (robin@x-plane.com).   This data is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.  You should have received a copy of the GNU General Public License along with this program ("AptNavGNULicence.txt"); if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. ** this file adds the missing ILS-cat-I to LIRN 06 - wkitty42 **

4  40.88688900  014.28988900    294 11015  18      52.736 NPC  LIRN 06  ILS-cat-I

"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Low Framerate

Postby SurferTim » Thu Nov 07, 2019 5:49 pm

@wkitty42: Thanks! I'll try that.
Fly low, fly slow, land on a dime. Twin Otter DHC6-300+.
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Re: Low Framerate

Postby Robertfm » Thu Nov 07, 2019 6:11 pm

Well I've just done a comparison test on my system with the results here: https://www.userbenchmark.com/UserRun/21541173 So it appears to be working fine itself as the stress test showed. I also activate my copy of FSX and with a plane sitting on a runway engine active I was getting 100+ Frames per sections. No that isn't a mistake.
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Re: Low Framerate

Postby Thorsten » Thu Nov 07, 2019 9:13 pm

I also activate my copy of FSX and with a plane sitting on a runway engine active I was getting 100+ Frames per sections. No that isn't a mistake.


Yeah, FG also gives me 120+ fps on the runway if I don't throttle framerate - which I have to do, because several tasks don't work properly at over 60 fps.
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Re: Low Framerate

Postby Robertfm » Thu Nov 07, 2019 9:19 pm

As you are here perhaps you could explain then why I am getting such a poor frame rate when I've shown there is nothing wrong with my system.Why was I not surprised when mentioned FSX I would get an indignant response.
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Re: Low Framerate

Postby wkitty42 » Thu Nov 07, 2019 11:35 pm

i see no indignant responses...

on my system, clouds are recently ripping my frame rate down... i've reduced my cloud density to 0.25 from 0.50 and that helped... especially when leaving KLGA with a fully overcast sky while headed to KSFO... once i got completely away from the clouds, i was getting a nice FPS of 25 or so... i have an NVIDIA GT730 GPU, though...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Low Framerate

Postby GinGin » Fri Nov 08, 2019 7:34 am

So the problem is the Fps decrease over several hours, not at initialisation ?
You said you got between 60 and 120 at beginning.
So that would be interesting When you do comparison to let games run several hours like in Fg to observe that fps tendency to decrease

Is the game and the terra gear data on a ssd or different locations ? Could you monitor the disk reading / writting and swap memory access ?
Even if Ram is not fully used, game might access to the disk for terrain data quite a lot, and hdd might be the culprit there

You should monitor , with screens or parameters recorder what happen each time fps decrease from the start
.
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Re: Low Framerate

Postby Thorsten » Fri Nov 08, 2019 8:16 am

As you are here perhaps you could explain then why I am getting such a poor frame rate when I've shown there is nothing wrong with my system


No, I can't - I'm not clairvoyant. Basically you need to figure out the bottleneck yourself by successively disabling an enabling various elements.

I've been testing framerate on three different computers for the last decade - they were all held up by different things. My first computer struggled with the fragment pipeline and so I tended to code to make it lean and do work in the vertex shader, but then newer graphics cards turned out to be not much faster in the vertex pipeline but massively faster in the fragment pipeline, so the whole problem was reversed.

Trees as coded initially by Tim Moore (?) had the cool feature that their opaque interior was written into the depth buffer and only the transparent pixels were all rendered, massively reducing the amount of fragment processing for overlapping trees in forests. Unfortunately doing two passes instead of one turned out to be rather expensive for the Macs, so the overhead from the pass rather than the fragment processing time turned out to be the decisive factor on some computers, so the whole idea of two passes was dropped (which was actually slower for me, but helped James a lot).

So with some experience I can tell you what the bottleneck on my systems is (always takes a bit of time to find out and diagnose) but I sure can't do it remotely.

I'm now guessing, but since FSX is over a decade old and a 32 bit application, I assume it's really not that heavy on the graphics card - neither in terms of GPU memory usage (32bit and memory limit - my GPU alone has twice the memory a 32bit application can handle...) nor in terms of GPU workload. For instance, my understanding of seasons and low sunlight in FSX is that they're using pre-computed texture sets, so the variation you'll see in seasons and sunrises is limited - in FG it's all computed dynamically, so no two sunrises will look the same and seasons form a continuum of how the terrain can look like - but of course computing it runtime costs more on the GPU.

Well, the long story short - you'll have to track down the decisive element that costs you framerate yourself because they're very unlikely to exist in the same way for me - no two computers I've ever owned had precisely the same bottlenecks, so it'd be a miracle if yours does. Unlike a commercial software manufacturer who can afford to buy a range of different architectures and test their software on all of them, FG developers only have access to a limited number of computers - I habitually test three different setups (Linux on two computers, one with nvidia driver, one with nouveau driver, Windows on a third machine) - that's all the testing I can do. If some other architecture has a quirky bottleneck, I can't diagnose or fix it without the person who has the problem doing the detailed diagnostics what precise effect/shader/part of the scenegraph causes the slowdown.
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Re: Low Framerate

Postby Robertfm » Fri Nov 08, 2019 10:36 am

GinGin wrote in Fri Nov 08, 2019 7:34 am:So the problem is the Fps decrease over several hours, not at initialisation ?
You said you got between 60 and 120 at beginning.
So that would be interesting When you do comparison to let games run several hours like in Fg to observe that fps tendency to decrease

Is the game and the terra gear data on a ssd or different locations ? Could you monitor the disk reading / writting and swap memory access ?
Even if Ram is not fully used, game might access to the disk for terrain data quite a lot, and hdd might be the culprit there

You should monitor , with screens or parameters recorder what happen each time fps decrease from the start
.


The is on the C drive< no idea how to change drives>.
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Re: Low Framerate

Postby V12 » Fri Nov 08, 2019 11:01 am

Robertfm :
Have You enabled AI traffic ?
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Re: Low Framerate

Postby Robertfm » Fri Nov 08, 2019 11:54 am

Yes it is enabled but I have already tested things with it off and it makes little difference. It was suggested a while ago. I have now shifted FG to my D drive which was empty and had 993GB.
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Re: Low Framerate

Postby GinGin » Fri Nov 08, 2019 12:21 pm

The question was: is it an ssd or hdd where you had Fg installed ?
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Re: Low Framerate

Postby Robertfm » Fri Nov 08, 2019 2:37 pm

They are HDD Toshiba HDWD110 & SSD Kingston SA1000M8240g. It was on the SSD now on HDD. No difference an hour into flight FPM dropped from 60 to 30.
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