Stutters - CPU0 okay but not others. How to fix?

[Ray Proudfoot 8,927]

I've been reading the various topics on how best to manage P3D for smoothness with zero stutters. I'm running v4.5 with Nvidia drivers 442.59 and 30fps is set in NCP for P3D. VSync is on in P3D with T/Buff on and unlimited fps.

When taxiing at a fairly busy airport (EBBR) with Ai limited to 100 aircraft you can see CPU0 is fine. But the activity on the other processors varies quite a bit and it's when it hits 100% on one of those I feel that's when a stutter occurs.

Can anyone please suggest how to better manage those other processors? At present I have P3D assigned to use 0,2,4,5,6,7,8 and 9. Other programs use the other ones.

 

[Bert Pieke 7,584]

The "other" cores carry the P3D scenery loading tasks and can get saturated if you have your settings too high.. that introduces stutters.

SO.... the way to improve this situation is to reduce your settings in P3D.

[Twenty6 692]

I don't have the 8086, I have the 9700 (8 cores) which doesn't have hyperthreading. One thing I never do is run P3D with an affinity mask. CPU is not overclocked, 16 GB of 3000 ram, 2x 1TB SSDs, RTX 2080Ti, 27" 4k monitor, 24" HD monitor

Other thing is to periodically run thru https://www.simforums.com/forums/nvi-w7810-driver-setup-fsx-fsxse-and-p3d-update_topic59954.html

No stutters ( and I like to fly in thunderstorms and blizzards). Only thing I can't solve is the shimmering on runways and around instrument gauges.

[Ray Proudfoot 8,927]

9 minutes ago, Bert Pieke said:

The "other" cores carry the P3D scenery loading tasks and can get saturated if you have your settings too high.. that introduces stutters.

SO.... the way to improve this situation is to reduce your settings in P3D.

Yes, I guessed it would be the settings but I don’t have them set unreasonably high. I suppose I need to check which are CPU dependent but you’d think with 0 coping with the settings the other processors could too.

3 minutes ago, Twenty6 said:

I don't have the 8086, I have the 9700 (8 cores) which doesn't have hyperthreading. One thing I never do is run P3D with an affinity mask. CPU is not overclocked, 16 GB of 3000 ram, 2x 1TB SSDs, RTX 2080Ti, 27" 4k monitor, 24" HD monitor

Other thing is to periodically run thru https://www.simforums.com/forums/nvi-w7810-driver-setup-fsx-fsxse-and-p3d-update_topic59954.html

No stutters ( and I like to fly in thunderstorms and blizzards). Only thing I can't solve is the shimmering on runways and around instrument gauges.

I have a professionally built PC that is moderately overclocked. It came with HT enabled and I was advised to leave it on.

I’ve read Nick’s excellent advice before. Pity he can’t bring it up to date with current Nvidia options. But it’s still worth revisiting, thanks.

[Ray Proudfoot 8,927]

One other thing occurred to me. CPU1 and 3 are not currently assigned to anything. From the advice I read those two are paired to 0 and 2 and the advice was to leave them alone.

But they are barely utilised. Is that still the recommended setting?

[Quasimodo 505]

I use 30hz, Frame Rate = unlimited, Vsync and TB on. But I just discovered this. It might be unique to my Display which is a Samsung NU6900 UHD TV but its easy to try so long as your display supports 24hz.

1. set your refresh rate in NCP to 24hz.

2. Load settings that will delivery at least 30fps.

3. under display setting set Frame rate to 24, set Vysnc to on and leave Triple buffing off.

4. go fly.

If it works for you the way it worked for me you'll be happy.

Let me know how it worked out.

[Bert Pieke 7,584]

The way I understand it, is that P3D uses the first two processors that are available to it, to run its rendering and housekeeping tasks.. scenery loading is offloaded to the "other" cores.

In your case that would be 0 and 2.

If you are sitting still somewhere quiet, you will see Core0 very busy, and Core2 somewhat busy. That is the normal base case with no scenery loading going on.  In a HT scenario, it is indeed a good strategy to keep at least Core1 unused.

Since you have enough cores, leaving Core3 unused as well, protects the base P3D processes from being crowded out by other processes.

Now, to your question... "if Core0 is OK, the other Cores should also be able to cope"...

In my experience, you CAN overload the other cores with scenery and traffic, especially at, or near addon airports.

Just go and fly at Lihue, Kawaii as a test... lovely scenery, smooth performance no core saturation..

I am sorry, but your "reasonable settings" may be still be struggling with your scenery / airport selections..

The old analogy of the "Straw that broke the camel's back" still applies..

[Ray Proudfoot 8,927]

@Quasimodo, I will try that tomorrow and report back. But on reflection my BenQ only supports 30 and 60. Wouldn’t 24 be uncomfortably slow?

@Bert Pieke, I’ll try that too. I do use AIG’s Ai package but have limited traffic to 100 within an 80nm radius of EBBR (3rd Party addon). It shouldn’t be difficult to find settings that keep things smooth. I appear to have the cores correctly assigned for HT.

Edited March 23, 2020 by Ray Proudfoot

[Quasimodo 505]

18 minutes ago, Ray Proudfoot said:

my BenQ only supports 30 and 60

Sorry for bring it up. Its probably not for you then.

 

20 minutes ago, Ray Proudfoot said:

Wouldn’t 24 be uncomfortably slow?

I had tried it before with Frame rate = Unlimited and its not bad on final at all. Certainly, beats dropping below 30fps with 30hz.

But I just discovered or so it would seem that if I set Frame Rate = 24 instead of unlimited with 24hz it look far better than 30hz with Frame Rate = unlimited.

It actually looks more like 60fps with Vsync. I'm still a little shocked. My gut feeling is that its something to do with my UHDTV. Perhaps because it's a TV it's optimized for 24hz.

I'm even wondering if the fluorescent tubes in my office are 24hz. Or perhaps my eye's have changed over night. If so I have not other indications other than that with these setting

P3D runs a lot smoother. I kid you not. It look like 60fps with Vsync.

 

[Bob Scott 7,715]

1 hour ago, Ray Proudfoot said:

One other thing occurred to me. CPU1 and 3 are not currently assigned to anything. From the advice I read those two are paired to 0 and 2 and the advice was to leave them alone.

But they are barely utilised. Is that still the recommended setting?

Keep in mind that with HT enabled, these are virtual CPU cores...0 and 1 share a physical core, as do 2 and 3.  The virtual cores maintain a separate set of registers, but share the memory cache and execution unit.  When a thread runs on virtual core 1, it has control of the execution unit and core 0 is idle and vice-versa.  The first core available to P3D runs the main thread, and the second runs the scheduling thread, and you don't want the CPU sharing the core assigned to either of those threads with other P3D threads (e.g. scenery/terrain loading), so an affinity mask that prevents assigning other P3D threads to the paired vCPU on the first two physical cores is desired.

I don't think I'd keep P3D off of cores 10-11...let it share them with your ancillary programs.

I tried both HT on and HT off on my 8086K, and ultimately went with HT off...it was noticeable smoother, and no HT/AM gymnastics are needed.

 

[Afterburner 374]

Hi Ray,

This is apparently how P3D works. If you taxi at a busy airport, core 0 gets loaded to the full extent (which is a good thing - after all, you want to have the maximum possible CPU resources available). However, cores 1, 2, 3, etc. are not loaded extensively. That picture changes if you fly mid-air over complex scenery. In that case, you can see the remaining cores loaded to almost 100% when P3D loads the scenery en route. So the other cores are used by the sim.

A few years ago, I have used some tricks (e.g. affinity mask, switching affinity on cores on and off using the task manager) to have a more even load on all cores. It increased the FPS on airports after start, but the caveat from doing so was that when I was approaching an airport, there was a delayed loading of autogen and/or blurry textures. In this situation, you want to have full resources available by the other cores, and P3D does this as needed. I understand the thought process "I am taxiing at a complex airport, why does the sim not let other cores taking off some load so as to increase performance?", but I am afraid you can't have best of both worlds.

My suggestion is to leave things as they are and not use any "tweakers". I share this information from using a 4-core CPU. I am not sure how it is when using an 8-core processor.

[Mace 1,902]

I believe there is still an issue with P3D loading sim objects that can cause a stutter.

I won't comment on your setup because it's about as good as we can get, or at least that we know of -- at the present time.  I happen to be presently devoting all later cores to terrain loading, but that's the only significant difference between our setups.  As you know our hardware is very similar (6 phys core, HT=on, 30hz refresh, vsync on and fr unlimited).

 

 

[Ray Proudfoot 8,927]

@Quasimodo, don’t worry about having suggested it. I think I’ll try the simpler things like reducing scenery settings first and see how that goes.

@w6kd, Bob, I’ll try assigning all cores except 1 and 3 and take it from there. One change at a time so I can judge the impact. Pete Dowson has a test where he slews up to 500ft at EGLL and then rotates through 360° and observes the impact on fps. That’s the most severe test there is.

@Afterburner, the stutters occurred when I was taxiing in a Xtreme Prototypes Learjet 25 at a 3rd party EBBR so not a massive airport and the aeroplane is not a fps eater. The skies were clear too. The view at the time was pretty bland as I was taxiing away from the airport buildings towards 07L for departure. CPU0 usage was well off the max as the graph shows. That’s what I found so odd. Nothing that came into view could be considered taxing on performance.

@Mace, I think you’re right in that the core program has improved but there are still some issues to sort out. I’ll see if I can improve things by trying various sliders. But I doubt I can eliminate them completely. That probably needs v5! 🤨

[Bert Pieke 7,584]

1 hour ago, Ray Proudfoot said:

@Quasimodo,

@w6kd That’s what I found so odd. Nothing that came into view could be considered taxing on performance.

@Mace,  🤨

It is not only what "comes into view" that gets loaded.. it is all the traffic/scenery/etc within a 20nm radius or so..

Edited March 23, 2020 by Bert Pieke

[lownslo 592]

5 hours ago, Ray Proudfoot said:

When taxiing at a fairly busy airport (EBBR)...

Do you use FFTF Dynamic ?  It will help make even "fairly busy" airports more pleasant.

Also, did you try an AM of 4052 rather than 1013 (and run your addons on Logical Processors 0 and 1)?  I agree with Bob... I've tested my 8086K extensively with HT ON (I paid for the feature, and I wouldn't mind using it) but I prefer how the CPU performs with HT OFF.

Greg