Limiting Framerate kills framerate - why?

[Bobsk8 12,732]

1 minute ago, GHarrall said:

This is true Bob. But as you aren't a v4 user (v4.3 specifically) you may not be aware of the 'no autogen loading' and blurry issue that is a real problem running unlimited on this platform. There are a couple of long threads about it. The only fix right now is a locked frame rate in the sim.

This kind of screws everyone who was using unlimited FPS target with vsync and triple buffer on with  a 30hz refresh rate.

True, I stayed with V 3.4, mainly because I didn't want to have to buy a new PC. 

 

[Guest]

1 hour ago, darem said:

If I have framerates between 40 and 50 and limit them to 40, shouldn't I have stable 40 with more CPU time for textures and autogen?

No, in P3D when you switch from TFR = Unlimited (which is essentially operating the FFTF = 0.01) to 40 then you are now operating/using the FFTF = 0.33 (default unless you've modified it) ... with TFR = Unlimited the FFTF value defined in your Prepar3d.cfg is NOT used.  With with TFR = 40 and FFTF 0.33 is essentially saying I want 1/3 of your processing time to render autogen and terrain tiles.  From the numbers you've listed that's exactly what is happening.

If you were to leave TFR = 40 and edit the Prepar3d.cfg to change the FFTF value from 0.33 to 0.01 then your FPS will increase to the same (or very close to) that of Unlimited because you are no longer allowing the engine to spend as much time to render autogen and terrain tiles (which eventually leads to no autogen and/or blurries).

It's a CPU balancing act based on graphics settings used.

Cheers, Rob.

[Litmoose 90]

There's a big misunderstanding about how locked FPS limited actually works within the community, which only recentley seems to be coming to light. Most just lock fps to 30 and go "i locked my fps to 30 and only got 1/2 frame rate", then go back to unlimited, not understanding the reasons why.

 

It all evolves around your FIBER_FRAME_TIME_FRACTION=X.XX. This setting goes hand in hand which the insim FPS limiter. By default the setting is 0.33 which basically means your sim is dedicating 33% of reseources to loading autogen. Lowering the value will give more FPS, and setting it even higher(theres no need) would dedicate even more resources to autogen.

 

 this thread explains it alot better than i can. But in a nutshell, your need to find the right balance of FFTF for your system. Or use a the dynamic tool that i do from FSPS, which changes the FFTF on the fly depending on your FPS. 

 

By running unlimited frames you are basically dedicating 99% resources to FPS which is why you might find you're autogen isn't loading.

Edited August 13, 2018 by Litmoose

[Guest]

19 minutes ago, Bobsk8 said:

I stayed with V 3.4, mainly because I didn't want to have to buy a new PC.

Why would you need a new PC?  For equivalent graphics settings V4.x will perform faster than V3.x using the same hardware ... so not sure I understand?  Remember V3 = Max is the same as V4 = Medium when it comes to AG density/distances.

If you can't operate with any self control of graphic sliders, then yes P3D V4.x will put more load on your PC ... but that's your choice (at least you have the choice if you ever upgrade hardware in the future).  For settings equivalency you should see about 20% performance gain over V3 on the same hardware.

Cheers, Rob.

[Nyxx 6,993]

14 minutes ago, Rob Ainscough said:

No, in P3D when you switch from TFR = Unlimited (which is essentially operating the FFTF = 0.01) to 40 then you are now operating/using the FFTF = 0.33 (default unless you've modified it) ... with TFR = Unlimited the FFTF value defined in your Prepar3d.cfg is NOT used.  With with TFR = 40 and FFTF 0.33 is essentially saying I want 1/3 of your processing time to render autogen and terrain tiles.  From the numbers you've listed that's exactly what is happening.

And it's been like that since FSX.

If you run unlimited FPS and enjoy good texture, limited your FPS to e.g 30 and add this to your config file

[Main]
FIBER_FRAME_TIME_FRACTION=0.01

You get all the FPS that locking takes away back and I don't care what anyone says its as simple as that on most people PC's. Watch the video linked above its shows it all in action.

Edited August 13, 2018 by Nyxx

[Litmoose 90]

2 minutes ago, Nyxx said:

And it's been like that since FSX.

If you run unlimited FPS and enjoy good texture, limited your FPS to e.g 30 and add this to your config file

[Main]
FIBER_FRAME_TIME_FRACTION=0.01

You get all the FPS that locking takes away back and I don't care what anyone says its as simple as that on most people PC's.

Your correct, thats how its meant to work. But you will probally run into autogen loading issues. You might aswel run unlimited, the only reason for locking to 30 FPS would be for frame consitency.

[Nyxx 6,993]

11 minutes ago, Litmoose said:

Your correct, thats how its meant to work. But you will probally run into autogen loading issues. You might aswel run unlimited, the only reason for locking to 30 FPS would be for frame consitency.

Well not really, running unlimited is telling your PC to give as many fps as, come what may..... limiting stops that, for example at EGNX I run 55-70 with FSL/PMDG, I lock at 30 so my PC has " room to breath" it does the 30 not the "60" it could do. So when it has a more demanding screens to draw it has the "room to breath" that unlimited does not have you get big dips/stutters, locking stops that for more, makes everything smooth as am not asking the PC to run P3D as fast as it can. Like cruising on a motorway with your foot half way done, not foot to the floor all the time.

I run locked at 26, plus FIBER_FRAME_TIME_FRACTION=0.01 for FSL and locked at 31, plus FIBER_FRAME_TIME_FRACTION=0.01 and I get perfect texture loading and no stutters. VS  and TB ON, my refeash is 120hz. So it runs at 24 for FSL and 30 for PMDG.

Edited August 13, 2018 by Nyxx

[Litmoose 90]

1 minute ago, Nyxx said:

Well not really, running unlimited is telling your PC to give as many fps as, come what may..... limiting stops that, for example at EGNX I run 55-70 with FSL/PMDG, I lock at 30 so my PC has " room to breath" it does the 30 not the "60" it could do. So when it has a more demanding screens to draw it has the "room to breath" that unlimited does not have you get big dips/stutters, locking stops that for more, makes everything smooth as am not asking the PC to run P3D as fast as it can. Like cruising on a motorway with your foot half way done, not foot to the floor all the time.

I run locked at 26, plus FIBER_FRAME_TIME_FRACTION=0.01 for FSL and locked at 30, plus FIBER_FRAME_TIME_FRACTION=0.01 and I get perfect texture loading and no stutters.

Incorrect, by setting 0.01 your PC isnt utilising the "buffer". Its still only useing 1% towards autogen. if you set it to something like 0.15 you might lose a few frames overall in dense areas but your autogen would load.  

[jabloomf1230 2,445]

FFTF is a maximum limit. If a frame takes 33 ms (that's roughly 30 fps) to render and FFTF is 0.33, then a maximum of 11 ms will be spent running fiber jobs. As I understand it (and this hasn't changed going all the way back FSX), if 11 ms isn't needed, then the fiber jobs will use less than that. It's possible that LM changed the way that FFTF works, but the above concept means that FFTF could have values greater than 1.0. It's just an upper bound as to how much time is spent loading scenery textures.

 

[Nyxx 6,993]

9 minutes ago, Litmoose said:

Incorrect, by setting 0.01 your PC isnt utilising the "buffer". Its still only useing 1% towards autogen. if you set it to something like 0.15 you might lose a few frames overall in dense areas but your autogen would load.  

Yes that's the point I don't need any buffer.

Edited August 13, 2018 by Nyxx

[Guest]

20 minutes ago, jabloomf1230 said:

As I understand it (and this hasn't changed going all the way back FSX), if 11 ms isn't needed, then the fiber jobs will use less than that. It's possible that LM changed the way that FFTF works

That's my understanding also, but what has changed considerably from FSX and P3D V3 is the density and distance of Autogen.  So in FSX/P3D V3, with much less AG/Terrain to render, lower FFTF values on faster PCs didn't need the extra time to process fiber jobs.  But now that AG/terrain tile jobs are considerably more demanding due to the increased distance/density that V4 provides, Unlimited is just not allowing enough time to process the fibers for AG/Terrain when very high settings are used.

This is why Unlimited is going to be a difficult proposition if one is using very high AG graphics settings (beyond Medium) and flies at higher speeds.  Unlimited in V4 may still work well for those who fly low and slow where the slow speeds aren't as demanding on the AG/terrain system.  As always, it's a case of experiment.

Cheers, Rob. 

[fluffyflops 1,858]

3 hours ago, odourboy said:

I don't understand it either, but I get my best performance limiting my rates using vsync only and setting my monitor refresh at 30 (or 60) via Nvidia control panel and leaving frames unlimited.

Ditto

[jabloomf1230 2,445]

1 hour ago, Rob Ainscough said:

That's my understanding also, but what has changed considerably from FSX and P3D V3 is the density and distance of Autogen.  So in FSX/P3D V3, with much less AG/Terrain to render, lower FFTF values on faster PCs didn't need the extra time to process fiber jobs.  But now that AG/terrain tile jobs are considerably more demanding due to the increased distance/density that V4 provides, Unlimited is just not allowing enough time to process the fibers for AG/Terrain when very high settings are used.

This is why Unlimited is going to be a difficult proposition if one is using very high AG graphics settings (beyond Medium) and flies at higher speeds.  Unlimited in V4 may still work well for those who fly low and slow where the slow speeds aren't as demanding on the AG/terrain system.  As always, it's a case of experiment.

Cheers, Rob. 

Thanks. I posted that because people were questioning the use of FFTF > 0.33 with FFTF Dynamic. 

[B777ER 2,486]

3 hours ago, Rob Ainscough said:

That's my understanding also, but what has changed considerably from FSX and P3D V3 is the density and distance of Autogen.  So in FSX/P3D V3, with much less AG/Terrain to render, lower FFTF values on faster PCs didn't need the extra time to process fiber jobs.  But now that AG/terrain tile jobs are considerably more demanding due to the increased distance/density that V4 provides, Unlimited is just not allowing enough time to process the fibers for AG/Terrain when very high settings are used.

This is why Unlimited is going to be a difficult proposition if one is using very high AG graphics settings (beyond Medium) and flies at higher speeds.  Unlimited in V4 may still work well for those who fly low and slow where the slow speeds aren't as demanding on the AG/terrain system.  As always, it's a case of experiment.

Cheers, Rob. 

Rob, I followed your advice from the other thread and now limit my FR inside the sim to 29 (per SteveW). Also with Vsync on. Before I had unlimited and used NVI to limit frames to 30 and got real good performance. Now, with NVI frame rate shut off and limited internally via. P3D to 29 I am seeing much better AG loading. What I'm also seeing now though is higher heat and cpu load on the computer with all other settings being the same other than that described above. I'm seeing 90c and above at times and whole load up around the same. Does limiting internally cause more cpu strain and thus higher heat and load? 

Edited August 14, 2018 by B777ER

[Guest]

AutoGen is going to be more CPU intensive, they're batched which helps with performance but it's still a significant load on the CPU and I would expect the temps to go up when using TFR with FFTF value that keeps AutoGen rendering.  But you can run a simple test and set AG density/distance to Medium and if your CPU temps go down then you know TFR with high AutoGen settings is the source of your load/temps.  Oh, of course location will matter ... Orbx SoCal with FSDT KLAX is one of many good stress test points due to the density of AutoGen, EGLL is another hot spot.

Cheers, Rob.