Be careful with the FFTF tweak.

[Bobsk8 12,523]

I have just been flying P3D a shade over a week and love it. yesterday however was one of those days that reminded me of my old MSFS trouble shooting days.First, I had made a couple of changes to the P3D cfg file, which included the FFTF change.   After doing this, and changing some of the settings in P3D I was able to crank up my My Traffic settings and Active Sky NG and get a solid 30 FPS just about everywhere including the New York and Boston areas, so I was pretty pleased at the way P3D is working. 

 

Last night I decided to fly VFR from KBOS to KLGA, and took off from Boston in my A2A C 172.  The first part of the flight went with no problem, but when I got down to the eastern Long Island area, I pulled up the map im my A2A 172, and tried to change the zoom setting to read a VOR, and the map went Black. At about the same time my Mindstar GNS 530 stopped showing the airports and terrain and went dark except for the track line of my course. I closed and opened the map a couple of times, and eventually the display came back and the GPS started displaying again, but trying to change settings on the map again produced a blank map and GPS display. It looked like this. My GPS would show airports, I would open the map and hit zoom on the map, and the map would go dark and the GPS would go dark a few seconds later.  

 

 

As I got close to Laguardia airport, the map just refused to display the airports or terrain, and seemed stuck when it did, a few  miles behind where I had just traveled. The GPS didn't even show LGA or Kennedy Airport, except infrequently when it would pop up, as I cycled the map on and off. As I got on about a 6 mile final to LGA, I looked at the ground and it looked like a swamp, and I grew up right near there, and that is filled with homes and roads, not a swamp, so now I see I have a problem with the scenery too. Ok now time to trouble shoot, but where to start. At first I thought it was a GPS issue, since the GPS was intermittent, and not knowing how the GPS and A2A map work together, my thinking was maybe the map display get's it's info from the GPS. So I uninstalled and reinstalled the GPS, and wound up with the same thing. Now I am thinking maybe my A2A C 172 is faulty, so I tried flying the A2A Cherokee in the same area, because it has the same map and GPS in it.  This produced the same problem. Now I am thinking that the two aircraft that were installed separately could not have gone bad with the same symptom at the same time. I did notice one thing in trying to troubleshoot this problem, if I placed P3D in pause, the GPS and the Map worked perfectly. As soon as I came out of pause, it became faulty again. 

 

Before I retired, my profession included training component level techs on how to troubleshoot complex systems, and my Golden rule was always " If you suddenly run into a problem, go back to what you did last to make it worse" . I then remembered that the day before, I had made these tweaks to P3D because I am now convinced that P3D is where this problem is happening.  So I started checking on them one at a time, thinking that I would remove the tweaks to see if they had any effect on my problem. The first one I looked at was the FFTF tweak in the P3D.cfg file.  It was supposed to read  FIBER_FRAME_TIME_FRACTION=0.01 .   When I looked at it, this is what I saw FIBER_FRAME_TIME_FRACTION=0.00    I had mistyped the numbers when I added this to the P3D.cfg and changed it from 0.1 to 0.0 by mistake. This has something to do with the scenery loading time, and I had changed it to zero.  This is why the GPS, the Map and sometimes the scenery as it did when flying into Laguardia giving me a swamp, would not load. So the result was a blank display on the GPS and map, and not updating when flying, or when changing settings on the map, it not being able to update to the moving scenery position.  When I paused P3D. then it had time to load the new position, both map and GPS, so everything worked normally.  

 

​Anyway, it was a good learning experience, and shows that Pilot Error can always rear it's ugly head. . 

[vgbaron 3,491]

If you remove the entry completely - do you have the same behavior?

 

Reason I am asking is the FFTF defaults to 0.33 if there is NO entry. I SEEM to recall someone mentioning that setting it to 0.00 would ALSO default to 0.33.

 

If you run fine with no entry then it would indicate that p3D will try to use whatever setting that is >= 0.

 

Vic

[n4gix 4,947]

That was good thinking to recheck your last edit, and I'm glad you spotted the error. The following is not directed to you specifically, but rather to the entire community...

 

Honestly, I've never figured out the logic of thinking that by giving the computer less time to accomplish its assigned tasks that the end results are going to somehow magically be better...

 

The value of FIBER_FRAME_TIME_FRACTION represents a balancing act; one in which the sim allows the computer just enough time slice to accomplish its assigned tasks before spewing the combined results down the road to the video card.

[TheHoser11 39]

Honestly, I've never figured out the logic of thinking that by giving the computer less time to accomplish its assigned tasks that the end results are going to somehow magically be better...

 

Have you actually tried it? it works! Maybe not for some, but definitely for most who have tried it. It's not magic my friend.

[n4gix 4,947]

Robert, yes I have "tried it" but more to the point I fully understand precisely what the parameter is for, and moreover just how it is coded in the sim.

 

I also know that the lowest possible fraction is 0.1, and that is simply not enough time for all of the events to be processed completely.

 

Perhaps it would be easier to mentally translate the fraction to a percentage. Default is to give the processor 33% of any time slice to complete the threads assigned to it. Giving it only 10% of the time slice is going to severely curtail thread task processing.

 

A more reasonable range for 'tweaking' probably would be from 20% to 40% (0.2 > 0.4).

[TheHoser11 39]

I let my eyes do the talking and 0.01 -> 0.10 gives me the best results and frame rates. I see it as actually giving the CPU more time to process other events while the GPU does its thing.

 

Again, proof is in the eye of the beholder and this beholder finds the magic trick to be quite real.

[n4gix 4,947]

Well, you are correct in that one aspect at least. If you are happy, then all is well.

 

The trick with FFTF is you have to have the right balance...

 

too high and you get frame rate issues and missing frames...

 

too low and you get a ton of blurries and other problems as there is not enough time to complete the tasks of pre-loading scenery.

[Bobsk8 12,523]

OK, I am pretty computer literate, but have no idea whatsoever what this tweak accomplishes in P3d. I do know that when I placed it in the config file and restarted P3D I had about a 20% frame increase, and was able to crank up my My Traffic AI settings quite a bit, and still stay around 30FPS in 95% of the areas I fly in. No blurries at all even in areas like Metro New York City. 

[Ebs 114]

I let my eyes do the talking and 0.01 -> 0.10 gives me the best results and frame rates.

 

 

The trick with FFTF is you have to have the right balance...

 

If I had to choose between a MilViz developer and a man with talking eyes, I know who my money would be on!

 

...I kid, I kid! sorry.

Robert, what CPU/GPU are you running? I found FFTF at extremely low settings gave me a nice FPS boost and no noticeable degradation in quality but since upgrading my GPU, the same FFTF caused extreme blurring of the terrain (it would take literally *minutes* for it to catch up) and I figured the slight FPS boost wasn't worth the blurring so now it sits at default 0.33

 

A lot of P3D/FSX tweaks are so system-dependent it's unreal and the only advice to give is to have a go and see if it works for you.

[Guest]

FFTF is only used when one locks frames via the limiter.

 

For my setup when running 30Hz, then Unlimited + Vsync + triple buffer seems to provide the most fluid experience (most consistent time between frames) for me.  If you run 60Hz then you'll need to be able to stay above 60 fps everywhere at Unlimited + Vsync + triple buffer.

 

Personally I'd never lock frames and never use FFTF ... but FFTF = 0.01 is similar to Unlimited only you still execute the limiting code -- that extra code execution takes away CPU time.  Unlimited has less code to execute (no limiter) so will run a tad smoother with less CPU load (Vsync control is faster).

 

Cheers, Rob.

[Nyxx 6,993]

Only use with lock BUT and its a BIG but..if your useing orbx regions or OLC and see blurring, try .1 or .2 and if they do not resolve then delete and that like setting .3

 

Also you could try with blurring

[Display]

TextureMaxLoad=30

 

[TERRAIN]

SWAP_WAIT_TIMEOUT=30

 

I use both.

[WebMaximus 372]

FFTF is only used when one locks frames via the limiter.

 

For my setup when running 30Hz, then Unlimited + Vsync + triple buffer seems to provide the most fluid experience (most consistent time between frames) for me. If you run 60Hz then you'll need to be able to stay above 60 fps everywhere at Unlimited + Vsync + triple buffer.

 

Personally I'd never lock frames and never use FFTF ... but FFTF = 0.01 is similar to Unlimited only you still execute the limiting code -- that extra code execution takes away CPU time. Unlimited has less code to execute (no limiter) so will run a tad smoother with less CPU load (Vsync control is faster).

 

Cheers, Rob.

Didn't know this was only used when locking the FPS and that using it when running unlimited FPS could even make things worse.

 

Great info Rob, thanks!

[Guest]

Didn't know this was only used when locking the FPS and that using it when running unlimited FPS could even make things worse.

 

Let me clarify,  you can have a FFTF value set, but it will have NO impact if you have a Target set to Unlimited.  Doesn't make anything worse.

 

IMHO, the best method to use is decided by your monitors refresh rate:

 

60Hz monitor - 30-50 FPS use Lock + FFTF value

60Hz monitor - 65-80 FPS use Unlimited + Vsync + Triple buffer

30Hz monitor - 30-50 FPS use Unlimited + Vsync + Triple buffer

 

NOTE: some systems may not work well with Triple Buffer, but in my situation it does help smooth out the experience.

 

Cheers, Rob.

[WebMaximus 372]

Let me clarify,  you can have a FFTF value set, but it will have NO impact if you have a Target set to Unlimited.  Doesn't make anything worse.

 

OK, I thought you said below running unlimited will use less CPU vs using a very low FFTF value but maybe I misunderstood then. Anyway I've now removed the FFTF=0.01 tweak since I'm always running unlimited FPS.

 

Personally I'd never lock frames and never use FFTF ... but FFTF = 0.01 is similar to Unlimited only you still execute the limiting code -- that extra code execution takes away CPU time.  Unlimited has less code to execute (no limiter) so will run a tad smoother with less CPU load (Vsync control is faster).

[Guest]

 

 

OK, I thought you said below running unlimited will use less CPU vs using a very low FFTF value but maybe I misunderstood then.

 

I probably should have worded it better.

 

Cheers, Rob.