Let's talk about "Target Frame Rate"... again.

[Alberto Zanot 53]

Hello people!

In Prepar3D 4.3 i was experiencing the issue about autogen buildings loading very slowly: flying at low altitude at a reasonable speed of 300 and more knots, the more i was going forward, the less autogen was loading, resulting that after some miles P3D cannot load no more autogen in the very front of the plane.
Then i run into a topic here where a user was suggesting to use the Target Frame Rate limiter. And it actually worked.
The thing is that i really do not understand how it works, and i would like to discuss this with the community.
I understood that limiting the framerate actually helps P3D in computing all the calculations needed to make every aspect in the sim running fine, sync'd, from the AI to texture rendering to geometry calculations. As told, using a TFR in my case helped the sim to calculate better the autogen and show it correctly. Leaving it "unlimited" this tells P3D to use all the power only for visual rendering, and all other things like autogen calculation will suffer.

Crystal clear.

Naturally there is that huge FPS drop. The thing i do not understand is why the drop is inconsistent.
I try to explain: let's suppose i get 45 fps in a certain area with "unlimited" TFR. If i set TFR 45, fps drop to 20. And everything (including autogen) is fine. So this makes me think that my pc in that area can achieve 20 fps.

Why if i set TFR 30, fps are no more 20 but they drop, let's say, to 12-13?
Is TFR actually just a sort of "percentage" in the balance between frame rendering speed and other calculations?
Isn't it very misleading to call it Target Frame Rate?
Why don't call it "Visual fidelity vs. Frame rate balance"?
It is not a TARGET FRAME RATE at all...

Thanks for any informations and thoughts you would like to share.

[fghdgdfdfgfgf 111]

Sounds like you have vsync enabled. Vsync is the ultimate frame limiter.

the 15 FPS you’re getting is telling you that your settings are too strong for your hardware.  You can try:

1) remove vsync ....should raise minimum FPS but at the expense of some autogen loading issues and probable sync concerns with monitor

2) lower your settings ...or get better hardware

Edited November 8, 2018 by FunknNasty

[Alberto Zanot 53]

Hi Funk!

Vsync ultimate frame limiter, what u mean? I can set my monitor to 30hz and Vsync on in P3D, and infact it will go 30 fps, but the problem about computing is still there. It is absolutely different from setting TFR 30.

About point 2, well i have to agree. Anyways i am running an i7 3770K @4.5, GTX 980ti Amp Extreme, 16GB DDR3 @2400. Not cr@p, i would say.

Edited November 8, 2018 by Alberto Zanot

[Bob Scott 7,715]

Might help to read this:  https://www.prepar3d.com/forum/viewtopic.php?f=6312&t=120133&p=139706&hilit=fiber_frame_time_fraction#p139706

 

[fghdgdfdfgfgf 111]

hi Alberto-

vysnc is the great limiter because it limits our ability to fudge facts about the performance of our beloved computers. The vsync in your story is telling you in no uncertain terms that the system cannot maintain 30 FPS. So you have to lower your settings to maintain 30fps or turn vsync off and try a frame rate limit somewhere between 25 to 30 FPS and hope your monitor doesn’t mind it ....too much.  

Your hardware is fine but your settings need to match.

Edited November 8, 2018 by FunknNasty

[GSalden 4,656]

With Vsync On :

if your pc cannot maintain the refreshrate it will try at 50% of that. 

And If 50% is not possible then it will try at 25%.

so 30 - 15 - 7.5

 

[AnkH 2,233]

Are you sure, Gerard? If I am not wrong, this VSYNC behaviour of stepwise reduction of FPS is long time gone, nowadays nVIDIA forces triple buffering via driver and with triple buffering, you do not see this effect anymore. At least in my case: I have my FPS limited to 30 and VSYNC on, and I never see a sudden drop down to 15. If the scenario is heavy, the FPS are below 30, down to 20-23 in some Scenarios, but never directly down to 15...

[YoYo 374]

Sorry but I cant imagine how I can play with 30 fps in XXI century ;).

Its a big stutter, nothing more, if You use Track IR. Without Track IR, with stable view (something like 2d panel, front view only) its ok, but not for VC when You often change positions. My 2 cents. Not less than 60 fps its ok for me. I used unlimited or fixed 144 fps in cfg (refresh rate of my screen). Btw (the same difference is in P3D with smoothing):

 

Edited November 9, 2018 by YoYo

[JoeFackel 760]

37 minutes ago, YoYo said:

Its a big stutter, nothing more, if You use Track IR.

Using TrackIR on an tripple screen and fixed 20 (!) fps. No stutter, it is well configurated.

[AnkH 2,233]

6 hours ago, YoYo said:

Sorry but I cant imagine how I can play with 30 fps in XXI century ;).

I would instantly agree with you when we were talking about any other games than flight simulator. For me, the 30FPS limit is the compromise I accept now, as I certainly do not want to reduce the settings until I get 60FPS. For any other game, yes, the more FPS the better. But even then, using G-Sync, I am basically happy with anything above 40-50FPS, as long as the game is not a fast pacing ego shooter such as Battlefield. There I reduce the settings to get 100FPS or more. The Witcher 3 in contrast is perfectly fine with G-Sync and 50FPS.

[fghdgdfdfgfgf 111]

I run NO vsync - my framerate locked (in game setting) somewhere in the low 30's, right now it just happens to be 34 - the monitor at 150Hz.

 

Why no sync? ...because I fly in and out of LAX every single day with lot's of eye candy. Thank you Gerard

7 hours ago, GSalden said:

With Vsync On :

if your pc cannot maintain the refreshrate it will try at 50% of that. 

And If 50% is not possible then it will try at 25%.

so 30 - 15 - 7.5

 

 

Why lock framerate?  see below link ...thank you Bob

18 hours ago, w6kd said:

Might help to read this:  https://www.prepar3d.com/forum/viewtopic.php?f=6312&t=120133&p=139706&hilit=fiber_frame_time_fraction#p139706

 

 

 

==============================

And why run monitor at 150Hz? because it effectively masks any sync issues  .....as long as I'm above 25 fps my cockpit experience feels like 150 fps in full sync.

Edited November 9, 2018 by FunknNasty

[AnkH 2,233]

I would still try to aim at a even multiplier of your desired FPS (or at least as close to as possible). That's why I now use a limit of 30 on a 144Hz Monitor running "only" at 120Hz. In your case, I would once try 38FPS and 150Hz. Might provide you even better results (as long as 38FPS is not too far away from what your rig is capable of).