P3DV2.1 stutter or no stutter

[Guest]

It will give you the distance that you by default only get with the highest ultra shadows at low, med and high shadows, without the loss in performance that ultra gives.

 

Thanks Jeroen.

 

 

 

Exactly, the refresh rate is 60Hz and and you are running the sim at 34 fps so how is going to be possible to stutter free performance with those settings?

 

There seems to be some mixing of information about VSync and stutters ... they can be two different issues.  Unfortunately stutters can manifest from one or both issues -- where render engine is not keeping up with aircraft view position changes and/or running an fps below the monitors refresh frequency.  The two are related but they are actually different issues.

 

The stutter type I'm seeing is one that seems to "wait" too long for a process in the render pipeline to complete before proceeding to render the frame.  These are not Vsync related stutters, they're something else -- what exactly I don't know.  I experimented with the SWAP_WAIT_TIMEOUT values because the problem I was having seems to relate to a "wait" process ... in FSX I used a value of 2 as that worked well for my system.  However, in P3D I didn't have this entry (which defaults to 30), so I tried many different values to see what impact it would have and it had zero impact ... almost makes me think the entry is no longer being used in V2.1 (however it is still listed in their General Performance Tuning guide).

 

Something has changed between V2.0 and V2.1 ... using the same scenario in V2.0 I don't get stutters or tearing, but in V2.1 the exact same scenario results in stutters.  

 

Good article here on V-sync - screen tearing and stutters

http://en.wikipedia.org/wiki/Screen_tearing

 

Cheers, Rob.

Edited February 22, 2014 by Guest

[nyc01 0]

If your monitor runs at 60 and fps can't reach that number the framerate will drop to 30 and so you should try to at least stay above 30 to get good performance... or something like that.

 

 

 

The frame rate will drop if v-sync is enabled and stuttering will occur as the refresh rate/frame rate is divided.

 

 

 

 

if you limit at 30 fps will be under 30 and you will never be able to really reach that fps of 30.

 

 

It's no different then what we've seen in FSX or X-Plane with the ½ refresh rate option. If the frame rate can consistently match the refresh rate of display with v-sync enabled the stuttering is eliminated.

 

That's the whole reason behind the ½ refresh rate option and Nvidia's G-Sync to begin with. If you can't maintain 60 fps with a particular game but you can at least maintain 30 fps the option allows you to divide the refresh rate and run it at 30Hz.

 

The problem is the ½ refresh rate option isn't working with Prepar3d v2 so unless you force 30Hz on the display like I described earlier in this thread you are going to see stuttering unless you turn the settings down low and run at 60 fps.

These are not Vsync related stutters, they're something else -- what exactly I don't know.

 

 

 

If it's not v-sync related then why was able to eliminate then by forcing 30Hz on my display with v-sync enabled on two different systems? How come the stuttering is eliminated when the settings in Prepar3D are turned down to maintain 60 fps with v-sync enabled?

 

 

I would call it a refresh rate/frame rate mismatch issue not a v-sync issue which is present with every sim/game out there if you can't get the frame rate to match the refresh rate of the display when v-sync is enabled.

 

 

 

 

Good article here on V-sync - screen tearing and stutters

http://en.wikipedia..../Screen_tearing

 

 

 

Here's a better one that adds triple buffering to the mix -

 

 

http://www.anandtech.com/show/2794

Edited February 22, 2014 by nyc01

[Guest]

 

 

If it's not v-sync related then why was able to eliminate then by forcing 30Hz on my display with v-sync enabled on two different systems? 

 

I didn't say it wasn't V-sync related for you or anyone else, I was being specific to my situation.  There are two types of stutter related issues:

 

1.  Stutters from the render pipeline waiting (my low GPU utilization would seem to indicate this is happening to me)

2.  Stutters from V-sync related issues

 

 

 

How come the stuttering is eliminated when the settings in Prepar3D are turned down to maintain 60 fps with v-sync enabled?

 

In my case, this isn't happening, I've turned down details to maintain above 60 fps (and my monitor is 60Hz) and it still stutters.

 

I have been able to reduce the stutters considerably with FFTF so that indicates something going on with item #1, V-sync and triple buffering has helped with #2.

[nyc01 0]

2. Stutters from V-sync related issues

 

 

 

Or stutters related to the frame rate not consistently matching the refresh rate with v-sync enabled. The same stutters that are present with FSX and X-Plane (and a dozen other sim/games I run) when the frame rate doesn't match the fresh rate of the display.

 

 

 

 

 

In my case, this isn't happening, I've turned down details to maintain above 60 fps (and my monitor is 60Hz) and it still stutters.

 

 

Is v-sync enabled? If yes how are you confirming that is enabled and working?

 

[Guest]

Is v-sync enabled? If yes how are you confirming that is enabled and working?

 

Yes I have V-sync enabled, I don't have any tearing issues, hence why I believe it's working.  Like I said earlier, my stutters aren't related to V-sync.  Also V-sync can really only work when one exceeds the monitors refresh rate ... V-sync doesn't slow the monitors refresh rate down nor can it increase one's frame rate.

Edited February 23, 2014 by Guest

[Brian Doney 127]

Also V-sync can really only work when one exceeds the monitors refresh rate ... 

 

Minor niggle, this isn't quite correct, and is one of the reasons triple buffering is needed when fps drops below refresh, to avoid having sharp drops from 60->30 etc., that occur with double buffered vsync. The cost being increased input lag.

 

Adaptive vsync works as you describe, engaging vsync when at or above refresh, and disengaging it below.

Edited February 23, 2014 by Brian Doney

[nyc01 0]

Yes I have V-sync enabled, I don't have any tearing issues, hence why I believe it's working.

 

 

 

Set you frame rate to unlimited with the v-sync option enabled and then exit out of the sim and start it back up again and take a look at what your frame rate is.

 

I'm asking because when running on Windows 8.1 anyway v-sync is'nt staying enabled (which I mentioned earlier). I was able to reproduce this issue on two different systems and I'm in the process of trying it on a fresh install of Windows 7.

[Guest]

Minor niggle, this isn't quite correct, and is one of the reasons triple buffering is needed when fps drops below refresh, to avoid having sharp drops from 60->30 etc., that occur with double buffered vsync.

 

Oops, yes correct Adaptive V-sync, sorry.  

 

As I understand it Triple buffering is supposed to prevent input lag at the cost of increased VRAM usage.  What is puzzling to me (hopefully others can verify) is that if I turn on triple buffering in P3DV2.1 I see NO change in VRAM usage?  If triple buffering is working, I should see more VRAM being used, it's not.  And it should actually be making my GPU work a little harder, but again GPU usage is still very low.

 

At first I thought that maybe FRAPS could help me identify ... in theory with Triple Buffering, FRAPS reported fps will not be the actual fps ... and I imagine this will be the same with the internal FPS counter, unless LM made specific changes to the internal counter ... I think Beau hinted at no changes to that feature and even suggested it's not reliable.  

 

So as a test, I recorded using FRAPS at 30 fps, knowing that I wasn't able to maintain 30 fps I should have seen "duplicate" frames in the resulting FRAPS file ... so I load up Adobe CC and moved frame by frame ... no duplicates?  What the heck, now I'm really lost and confused.

 

I've also tried using with and without NI, no difference.

 

So maybe this really is a driver issue and hardware issue?  Is this how I got my 19% fps boost ... ugh.  I have made some progress, but it's still not as smooth at V2.0 using the same settings (same drivers) ... but that implies it's NOT a driver issue or does it?  I'm completely baffle at this point.

 

Rob

Set you frame rate to unlimited with the v-sync option enabled and then exit out of the sim and start it back up again and take a look at what your frame rate is.

 

I'm asking because when running on Windows 8.1 anyway v-sync is'nt staying enabled (which I mentioned earlier). I was able to reproduce this issue on two different systems and I'm in the process of trying it on a fresh install of Windows 7.

 

Hmmm...interesting, please do post back your results.

Edited February 23, 2014 by Guest

[nyc01 0]

Hmmm...interesting, please do post back your results.

 

 

 

I will Rob as soon as I get it installed but I was also hoping you could give us your results with the scenario I mentioned, did you check the frame rate when you think v-sync is enabled?

[Brian Doney 127]

Every 3D engine handles vsync/buffering differently, so unfortunately it is difficult to make a one size fits all statement, but triple buffering really only allows for a variable frame rate with vsync enabled, it really doesn't have much purpose otherwise. Vsync of any sort will by design introduce some lag, it is simply unavoidable.

 

By adding the extra buffer, there isn't any way to avoid a slight increase in input lag, though again, different engines will have different perceived results. The Frostbite engine, as an example, is actually decent (though not perfect) at minimizing input lag, and is triple buffered by default. On balance, the Source engine suffers from intolerable input lag with these options set. I used to play competitively on the source engine, and one of the tricks I used back then was to force triple buffered vsync, and then use an fps limiter to limit fps to one frame below refresh, so 59 or 119. This was a good compromise as it eliminated tearing completely, and because of the fps limiter, almost removed any trace of input lag. This also allows for a consistent frame rate, something that cannot be done letting the engine run full tilt. Using Source as an example, unlimited fps could fluctuate wildly between 100-300 fps, and such vast fluctuations will certainly have an impact on player performance.

 

Shooters are obviously very different though, and the pacing difference alone can make those micro-stutters that drive us all nuts in the sim barely an issue.

 

My experience so far with P3Dv2.1 shows a much better handling of sync issues at low frame rates vs FSX. I can almost be satisfied with a 24 fps lock in P3Dv2.1, where in FSX anything other than 30 or 60 is just bad, in my experience. Having said that, anytime you are away from a multiple or divisor of refresh rate, there will be the potential for perceived stuttering. 

 

I run a very lean sim by comparison to most of you. I do not do addon scenery anymore, no mesh, no roads, etc., and I run very conservative sliders. This obviously makes it very easy to achieve a nice fluid 30fps in all situations. The downside being, that when the rare occurrence of stuttering does happen, it is really noticeable, even if only transient, simply because it happens so rarely. For my usage, P3Dv2.1 is far superior in this regard, and I have had a very good experience with it if we leave it's other faults aside.

 

For now though, I am back to FSX until the more serious issues introduced with 2.1 are resolved.

[Guest]

did you check the frame rate when you think v-sync is enabled?

 

Not exactly sure what you wanted me to test but I did the following:

 

VSync OFF (initial state)

Start P3DV2.1  = 32-35 fps

turn VSync ON = 26-34 fps

Exit

Start P3DV2.1 = 32-35

turn VSync OFF = 33-35 fps

Exit

Start P3DV2.1 = 31-33 fps

turn VSync ON = 27-33 fps

Exit

Start P3DV2.1 = 28-34 fps

 

Not sure I can make any conclusions from this other than with VSync ON the frame rate counter reports a wider fluctuation in fps.

 

 

 

I run a very lean sim by comparison to most of you. I do not do addon scenery anymore, no mesh, no roads, etc., and I run very conservative sliders.

 

Sounds like you would be a great supporter for 64bit then if you don't do add-ons   :lol:

 

 

I can almost be satisfied with a 24 fps lock in P3Dv2.1,

 

This is what has me so puzzled, I was perfectly happy in P3DV2.0 with 22 fps (stutter free and smooth regardless of weather or aircraft, only time fps would drop is at FSDT airports, all other's FlyTampa, Aerosoft were fine) ... but I can't seem to replicate this in P3DV2.1.

Edited February 23, 2014 by Guest

[Brian Doney 127]

Sounds like you would be a great supporter for 64bit then if you don't do add-ons   :lol:

 

For me it really is about fluidity, almost to a fault  :lol:

 

We all have our things that matter most to us, for me, I wouldn't even install my home airport as a high detail addon scenery. It just doesn't matter to me. I also found that I spent more time focusing on those areas that I had scenery for, and neglecting far too much of the rest of the world. 

 

That said, a lot can still be done even with the defaults in a 64 bit environment, so while I am certainly in the low risk category for OOMs, it would be nice to have some headroom. High detail aircraft are certainly pushing the limits farther than ever, and those I certainly do appreciate.

 

 

This is what has me so puzzled, I was perfectly happy in P3DV2.0 with 22 fps (stutter free and smooth regardless of weather or aircraft, only time fps would drop is at FSDT airports, all other's FlyTampa, Aerosoft were fine) ... but I can't seem to replicate this in P3DV2.1.

 

 

Not really sure on that one. For me it was immediately noticeable, that 2.1 was doing a better job with frame timing. The thing that makes it tough to say though, is are we sure that the stuttering you are seeing isn't somehow related to the plethora of serious, performance impacting issues introduced with 2.1 ? 

 

Who knows.

 

It's honestly why I can't be bothered for now to go any further with 2.1 Too many indeterminate variables and incompatibilities. 

Edited February 23, 2014 by Brian Doney

[Guest]

Agree, increased realism is never free ... in many ways.

 

If I were doing something more than GA/commercial type flying, the fluidity would be more important to me ... but for relatively slow speed slow maneuvers I can live with these stutters.  LM are taking a looking at these issues seriously.

 

I keep 3 sets of P3DV2.x on my computer, virgin P3DV2.0, virgin P3DV2.1, and P3DV2.1 add-on equipped set -- it's relatively easy to swap them in/out ... Just have to remember that if I ever do another uninstall, I have to make sure I have my P3DV2.1 set "active".

Edited February 23, 2014 by Guest

[SRAces 76]

WOW!  You could go bonkers reading everything in this thread...lol.  I applaud your efforts to get it right on your individual systems.  A lot of great inputs here.

 

I wish I could offer an input to help, but I just don't have that many tweaks in mine and do not use a lot of the suggestions mentioned.  I run mostly at 5450 X 1080 on my Surround setup.  I can run it full screen, but I get better frames at the slightly pulled in resolution in "windowed" mode.  I still believe each of us has to find out what works with our individual PC hardware, drivers, addons, etc..

 

What one person achieves might not be doable on another person's setup.  But it's interesting reading to say the least.

 

I do overclock my CPU and GPU slightly and that seems to help my frames.  No stutters.  I thought I would post a few shots of my settings and a couple of screens out of Cordova-Smith in the Orbx SAK region.  I haven't loaded my fixed Cordova-Smith back in yet.  I can fix the taxiways that are missing, but will wait on Orbx to release the fixes for each region.  Opus Weather is turned on in the shots.  Good luck with your efforts.

 

Steve

 

 

 

 

Edited February 23, 2014 by SRAces

[nyc01 0]

Not sure I can make any conclusions from this other than with VSync ON the frame rate counter reports a wider fluctuation in fps.

 

 

 

 

I should have been more specific, you'll have to use settings (or an airport/scenery area) that will allow for a frame rate higher than the refresh rate of your display, which I assume is 60Hz so you'll need to obtain frame rates higher than 60 fps.