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Very low framerates  Topic is solved

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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Very low framerates

Postby TheEagle » Tue Jul 13, 2021 8:02 pm

I recently flew in Scotland near Tiree (EGPU) in the Cessna 208B. There I had a framerate of 7 - 10 with high Graphics settings:
Code: Select all
Anti-Aliasing Disabled
ALS renderer on
Water effects High
Clouds detail Low
Model effects Enabled
Wind effects Enabled
Pylons and powerlines Basic
Buildings OpenStreetMap data
OpenStreetMap trees Enabled
Vegetation Shadows Enabled
Roads and railways Enabled
Random scenery objects Disabled
Autogenerated vegetation Disabled
Scenery objects Enabled
Photoscenery On

But, when I restart with the same settings at EDDF, I have a framerate of 1-2. This is logic, because at EDDF, there are lots of trees, pylons, Buildings, etc.
So I tried putting everything to the minimum:
Code: Select all
Anti-Aliasing Disabled
ALS renderer on
Water effects Disabled
Clouds detail Low
Model effects Enabled
Wind effects Disabled
Pylons and powerlines Disabled
Buildings Disabled
OpenStreetMap trees Disabled
Vegetation Shadows EDisabled
Roads and railways Disabled
Random scenery objects Disabled
Autogenerated vegetation Disabled
Scenery objects Disabled
Photoscenery Off

Even after completely restarting FG with these low settings, my framerate stayed at 3-5 !

Additionally, I never see my CPU at 100% when running FG alone - why ???? I expected my CPU to run at 100% all the time !

I am running FG version 2020.4.0 on Ubuntu 20.04 Studio.
Intel(®) Celeron(®) CPU B815 @ 1.60GHz 2 cores
4GB ram
6GB swap space
Graphics card is a NVIDIA Corporation GF119M [GeForce GT 520M] (rev a1)
My PC is a Acer Travelmate 5360
Hard disk is a 256GB SSD
Graphics drivers are nvidia-driver-460
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Re: Very low framerates

Postby danielHL » Wed Jul 14, 2021 12:25 am

Hm, I may be wrong - but your CPU, GPU and entire system seem to be from 2011. I'm not sure what you expect, but I'd be happy if fgfs ran with minimal settings in a remote location on this machine.

Flight simulation is very resource intensive, most notebooks aren't up to the task at all. I would suggest you upgrade at least to a system with a 3GHz CPU and a GPU like an older GTX760 or so will be fine. Add lots of RAM, 8GB is the absolute minimum to fly in dense areas.
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Re: Very low framerates

Postby TheEagle » Wed Jul 14, 2021 12:39 am

Okay, but I can't get better hardware right now. Do I really need so much RAM, or would increasing the SWAP space be an adequate solution, too ?
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Re: Very low framerates

Postby vnts » Wed Jul 14, 2021 2:44 am

TheEagle wrote in Tue Jul 13, 2021 8:02 pm:Additionally, I never see my CPU at 100% when running FG alone - why ???? I expected my CPU to run at 100% all the time !

You have two cores, and both need to be maxed out to see 100% - even when CPU bound one core with the CPU bound thread tends to be maxed while other's aren't. In your case it's also possible you are GPU bound in either fragment processing (if running windowed mode and reducing resolution increases FPS) or vertex bound (if looking at a part of the scene with low vertices like the sky increases FPS).

TheEagle wrote in Tue Jul 13, 2021 8:02 pm:I am running FG version 2020.4.0 on Ubuntu 20.04 Studio.
Intel(®) Celeron(®) CPU B815 @ 1.60GHz 2 cores
4GB ram
6GB swap space
Graphics card is a NVIDIA Corporation GF119M [GeForce GT 520M] (rev a1)
My PC is a Acer Travelmate 5360
Hard disk is a 256GB SSD
Graphics drivers are nvidia-driver-460


You probably need to tweak and experiment a lot, maybe for each different area you fly in.

Since it's a notebook , there probably isn't a way to upgrade GPU (maybe RAM could be upgraded if you can find 2nd hand RAM)

Running older WS1 scenery might help, as might running craft from older FG versions. LoD rough controls how far out scenery is loaded, and should also reduce RAM usage a bit.

See discussion from an earlier thread on older hardware viewtopic.php?f=37&t=39235#p386867

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Re: Very low framerates

Postby TheEagle » Thu Jul 15, 2021 9:13 pm

The problem is that both my CPU cores run at 40-50% all the time when I fly with FG at, say, EDDF. My framerate is at 2 - 4. As soon as I look at the sky it goes up to 10 fps - but the CPU stays low all the same. How can I make FG use 100% CPU on both cores ? I won't mind if other applications become slower by this - when I fly in FG, I don't surf in the internet or suchlike, anyways !
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Re: Very low framerates

Postby Johan G » Thu Jul 15, 2021 9:32 pm

You are very likely limited by GPU performance rather than CPU performance. Also, if you where to have even near to 100% CPU load something would be very wrong with either FlightGear or your OS.
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Re: Very low framerates

Postby TheEagle » Thu Jul 15, 2021 10:19 pm

Johan G wrote in Thu Jul 15, 2021 9:32 pm:You are very likely limited by GPU performance rather than CPU performance.

Ah, and how do I increase them, if I may ask ? :roll:
Johan G wrote in Thu Jul 15, 2021 9:32 pm:Also, if you where to have even near to 100% CPU load something would be very wrong with either FlightGear or your OS.

WHY ? I don't understand anything now ?!? :? :?: :shock:
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Re: Very low framerates

Postby WoodSTokk » Fri Jul 16, 2021 12:33 am

Your CPU has 2 cores. The OS calculate the sum of all cores for 100%
The core of FG is single threaded, so it can only occupy 1 core.
If one core is near 100% and the other one does mostly nothing, your OS will say 50%.
As example my CPU has 4 cores and if i run FG, the performance monitor show the CPU on 25%.
Yes, there are some parts that FG can run in a separate thread, but thats not much. The maiin loop is single threaded.
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Re: Very low framerates

Postby TheEagle » Fri Jul 16, 2021 11:07 am

Ah, thanks WoodSTokk - I now understand better ! :) But - can I do anything to make FG use _more_ CPU ? Because that would get me higher fps :(
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Re: Very low framerates

Postby V12 » Fri Jul 16, 2021 1:13 pm

No, You can't. This is reason, why I chaged sim.
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Re: Very low framerates

Postby wkitty42 » Sat Jul 17, 2021 12:15 am

TheEagle wrote in Fri Jul 16, 2021 11:07 am:Ah, thanks WoodSTokk - I now understand better ! :) But - can I do anything to make FG use _more_ CPU ?

no, why would you?

TheEagle wrote in Fri Jul 16, 2021 11:07 am:Because that would get me higher fps :(

maybe, maybe not... most likely not... at least not what you appear to be looking for...
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Re: Very low framerates  

Postby Hooray » Sat Jul 17, 2021 8:44 am

TheEagle wrote in Thu Jul 15, 2021 9:13 pm:The problem is that both my CPU cores run at 40-50% all the time when I fly with FG at, say, EDDF. My framerate is at 2 - 4. As soon as I look at the sky it goes up to 10 fps - but the CPU stays low all the same. How can I make FG use 100% CPU on both cores ? I won't mind if other applications become slower by this - when I fly in FG, I don't surf in the internet or suchlike, anyways !


You can use the following, so called "minimal startup profile" to determine the maximum performance your system can provide with most features/functionality disabled (which includes disabling terrain/scenery, effects/shaders etc).
FlightGear will really look "minimal" at that point - however, the point of the exercise is to enable you to tell just "how costly" certain features are, i.e. once you begin re-adding them back (re-enabling features one by one).

The following screen shot shows FlightGear 3.2 using the minimal startup profile on a system from the 2007 era (dual core, 4gb RAM, 756MB VRAM):

https://wiki.flightgear.org/Minimal_Startup_Profile
Image

So, speaking in general, it is indeed possible to run FlightGear on this type of system - but you will definitely need to a bit of research to determine what's possible in terms of aircraft/scenery/visibility etc - and basically you'll be more likely to succeed with certain types of flying (think IFR/IMC without much scenery/visibility).

Likewise, flying fast will stress test the terrain engine, so it's a better idea to use a slow aircraft given your specs.

Other users have even toyed with building custom terrain (tiles) for certain areas, to additionally reduce the system load.

Another option is using a combination of effects/shaders to procedurally reduce the complexity of certain textures and terrain features, assuming that your system supports shaders.

You should also consider using the built-in OSG stats monitor and the performance monitor:

https://wiki.flightgear.org/OSG_on_screen_stats
Image

https://wiki.flightgear.org/Howto:Use_t ... em_monitor
Image
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Re: Very low framerates

Postby TheEagle » Sat Jul 17, 2021 12:51 pm

Hmmm - using the minimal profile I only got 60 fps - nothing compared to your 500+ fps ... Looks like I'll have to live with stuttering. One last question - what could I do on the hardware side to improve my fps ?
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Re: Very low framerates

Postby Hooray » Sat Jul 17, 2021 1:36 pm

TheEagle wrote in Sat Jul 17, 2021 12:51 pm:Hmmm - using the minimal profile I only got 60 fps - nothing compared to your 500+ fps ...


No, that's to be expected (search for "vsync") - basically, FlightGear and/or your driver/OS will use a sensible update rate, in sync with the refresh of the screen/monitor, which is why 60 hz does make sense.

Anyway, 30-60 fps/hz is indeed what most people would consider "flyable" (playable).
Thus, you could use these settings now and incrementally re-add other features to see which ones have an impact.
For instance, you could try different aircraft (the ufo/ogel being fairly lightweight).
Then, you could tinker with different locations and visibility settings.

Ultimately, you will almost certainly have to stay away from complex airliners with many Canvas MFDs, similarly aircraft like the Extra5000 are probably also not suitable.
The shuttle will be too complex, too. But you might be able to find lightweight single engine airplanes with a "steam cockpit" (and possibly a 2D panel) that you can use for certain types of flying.

For example, if scenery/terrain complexity is too much for your system, you could use a different/custom set of terrain tiles, or simply do ocean flying (or flying in unpopulated regions). You could also check if carriers are working for you or not.

Looks like I'll have to live with stuttering. One last question - what could I do on the hardware side to improve my fps ?


Adding more RAM is probably the easiest thing to do. Using an SSD drive might help with disk I/O related latencies.
Other than that, a CPU/GPU upgrade would obviously help, too - but that will involve opening your notebook - and back in 2011 only very few laptops had support for replacing/upgrading built-in GPUs (called "MXM" back in the days).

The good news is, that your system is so old, that doubling your RAM or adding an SSD can surely be done for under $100 bucks.
A CPU/GPU upgrade would be more involved and would only make sense if you can get used/refurbished parts that are compatible with your system.
Otherwise, you're paying more for the work - given that a refurbished PC with >= 2gb of VRAM, >=16 gb of RAM and >= 8 cores is typically in the $200-300 USD ballpark

Speaking in general, getting a refurbished workstation/server and upgrading that by adding a dedicated OpenGL card, will provide plenty of bang for the buck; search.php?st=0&sk=t&sd=d&sr=posts&keywords=workstation+server+vram


How to install OpenGL
Hooray wrote:The recommendation looks sound, if possible it would be great if you could help us update the hardware recommendations accordingly.
Like I said elsewhere, even an "old" (3-5 years) used/refurbished Nvidia based quadcore workstation with at least 2gb of VRAM and 16gb of RAM will usually be in the 200-300 USD ballpark and should provide plenty of horsepower, and it's likely to take years before it will require an upgrade, at which point 150 USD for a better graphics card will go a long way. Things like Vulkan are unlikely to become relevant until a handful of long-standing core issues are addressed.


Minimum and recommended computer spec?
Hooray wrote:a quad core system, with 16gb of RAM and dedicated graphics with 2gb of VRAM still is a fairly decent system these days, even as a mobile device.
Still, it's probably what I'd consider the "minimum" these days for people wanting to set up a system specifically for FlightGear.
Obviously, FlightGear isn't "Crysis" - but anything much lower than these specs, might be frustrating by future developments.

However, like I said, I would be very surprised if over the course of the next 36-60 months, FlightGear would address all its technical/architectural challenges that are currently preventing it from leveraging modern gaming rigs.

FlightGear simply isn't there yet - and even if the core team were able to address core most issues, there simply is too much fgdata stuff (Nasal !!) that cannot easily be ignored - even the way people currently tend to use Nasal + Canvas is highly problematic from a rendering standpoint, if you want fast rendering, it simply is not a good idea to set up subsystems or avionics in Nasal space using timers and listeners, which then update properties to in turn update a FBO/RTT context to update a MFD ... this kind of thing is prohibitive when it comes to modern OpenGL/OSG, let alone anything involving Vulkan and multi-threading.

Which is to say, an 8-core system (2-3 ghz), 16+ gb of RAM, 2gb of VRAM is certainly going to suffice for quite a while... and using a workstation like the Z800 will provide plenty of buffer to grow over time - Compared to X-Plane or MSFS FlightGear simply isn't there yet, so there really isn't much to be gained from buying the latest gaming rigs, unless you happen to be into turning on all the latest eye candy (effects and shaders), or if you're a contributor/developer.
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Re: Very low framerates

Postby Husky Dynamics » Sat Jul 17, 2021 6:25 pm

Hooray wrote in Sat Jul 17, 2021 1:36 pm:Ultimately, you will almost certainly have to stay away from complex airliners with many Canvas MFDs, similarly aircraft like the Extra5000 are probably also not suitable.
The shuttle will be too complex, too. But you might be able to find lightweight single engine airplanes with a "steam cockpit" (and possibly a 2D panel) that you can use for certain types of flying.


As a side note, the FGAddon B-25/B-25J also seems to be really light on performance, despite being a nicely detailed aircraft. You could give that a try too if you want.
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