Huge lag spikes (2-4 seconds)... help?

[ryanbatc 12,856]

For the past month or two I've been getting horrid lag spikes when flying.  If I'm panning the camera around my plane my sim will just pause for 2-4 seconds at a time.  GPUz shows memory around 3.5GB (I've got a GTX 970 with the memory bug - so 3.5 of full speed and 4GB total).  The GPU load is around 60-70%

Windows task manager shows physical memory around 7 - 7.5GB.  I've only got 8 (8175 MB to be exact).  It lists available in MB at roughly 200-400 as I fly, and Free at 0.  The CPU cores on my 2500K are about 90 / 60 /70 /60 for percent usage per core.

In the sim displaying frame time....  the cpu and gpu numbers fluctuate often... especially when the lag happens.  At that point the GPU could go up to .6xx and the cpu the same.... but generally they are matched around .200 - .300.  If one is higher it's typically the CPU frame time.  FPS overall average around 25-30.

Something changed with the 11.10 final that just crushed my PC.  Obviously the older PC is to blame.  But with that data above... do you guys know what would be the primary culprit for the stutters?  Is it the RAM?  Paging to my drive?  Windows is a sata II SSD.  XP is a sata III.  And I do have Ortho on a 7200 rpm HDD mlinked to the scenery ini.

[2wheelsup 0]

post deleted

Edited January 22, 2018 by 2wheelsup
wrong forum

[bgpearce01 36]

Yes @ryanbatcund. Running anything at max ram/vram is going to cause problems. When panning around,  your loading in new textures and since your available ram is gone, it has to be switched in. Keep in mind 7.5 of 8 gb should be considered full. There are reserved spots in the memory that cannot be accessed. Also, it may request a memory block larger than any space available. 

[Janov 2,383]

Definitely a memory problem. Reduce your load by lowering texture setting, avoiding HD-Mesh and/or Orthophoto Scenery - also add-ons with a large texture bill (aircraft or custom airports) can push you over the edge.

I had the same setup you do (i5 2500k with 8GB, Geforce 970) and I had to be careful to not exceed memory (both VRAM and RAM).

There is a short lag spike when loading a large texture the FIRST time - that is unavoidable. So you want to pan around your cockpit once while on the ground so that the texture gets loaded - to avoid the lag later during flight. This only works when your TOTAL memory usage is below your limit, though. Otherwise the rear wall texture and the instrument panel texture will get swapped (with a little lag) everytime you look forward and backwards.

Cheers, Jan

 

[soaring_penguin 428]

HI Ryan, what you did not check, is the swap page useage. What I expect you will see is that there is disk activity during those spikes, then, as others stated, you ran out of physical RAM and started swapping.

Also exceeding VRAM with only a few percents, will cause swapping between VRAM and RAM, which is also a cause for stutters. RAM is much slower then VRAM, and in any case, swapping puts extra workload on the buses.

And I am not sure how this turns out with the 3.5 GB / 4GB limit on the 970, but I heard this could cause similar issues.

Best advice is to increase memory to 16GB, then you should be fine.

[Michael Moe 495]

I also noticed these micro stutter/FPS drop when panning using Chaseplane and GTX970´s in SLI lately. Sometimes also just looking down or up

Was wondering if the CPU mask was a problem. Tried moving Chaseplane off core 0 but i think Chaseplane needs all the power sometimes. 

Might be the magic 3.5GB VRAM issue as i have 16GB DDR3 - 2400 RAM .

Process Lasso is showing nothing more than 40-45% RAM usage.

 

 

Thanks

Michael Moe

 

 

[Old_As_Dirt 160]

13 hours ago, ryanbatcund said:

Something changed

Ryan,

While I don't have a "monster" setup, I do have an i7-4770 CPU, a GTX 1070 8 GB video card, and 16 GB of RAM.  All this on a very capable board.  I can, with most everything on the left side of graphics settings at max (including anti-aliasing) and the right side at (as you move down the settings) one notch below max and reflections at one notch up from minimum, get mid 50s as an average.  This is using the default C-172 at about 3900 feet over rural terrain.

It will fly along smoothly at these settings until I either look around or, sometimes, when it is going into a turn as the GPS calls for.  Then it will sometimes, not always, stumble (stutter) down into the teens and just jerk around through the turn (either as the plane turns or as my head turns - TrackIR).  I have suggested that Laminar "dampen" the turn rate in the GPS settings, but don't know if that would really help.  I say this because when flying FMS in large aircraft, I don't see this and really don't notice the head turning stutter.  This may be because I am flying at a much higher altitude and the scenery is not as intense but that doesn't make sense because the aircraft interior is much more complicated.

Yes, part of your problem is your equipment, but comparing it with mine, it is not all of it.

I bought the 1070 as an upgrade from my 770 4 GB and, where the memory usage in the 770 was running at about 3600 (measured with Z-GPU), it now runs at about 5400 memory usage.  The picture IS a little clearer and it is apparently giving me more stuff (running anti-aliasing at 8 does not draw down FRs at all) it still stutters.

I therefore have to assume that it is in the programming and I am not a programmer, so just have to wait on VULCAN or whatever, but it just seems that if it runs at 50, it should stay at 50 or close to that - and it doesn't.

John

[ryanbatc 12,856]

For now I've brought the texture res down to medium... which is annoying.  This will probably make me fly P3D4 a lot more often...  even though that sim uses almost all of my RAM it won't usually use all my vram.

[greggerm 312]

Ryan... this might shed some light on your current situation...

http://hexus.net/tech/news/graphics/79925-nvidia-explains-geforce-gtx-970s-memory-problems/

The Geforce GTX 970's have a "unique" memory and processing architecture which when pressured to 3.5GB+ of VRAM usage, start to exhibit, umm, issues. Given X-Plane might be attempting to leverage as much VRAM as possible, you might be headbutting right into this problem.

Good luck,
-Greg

[kneighbour 32]

I have a pretty good system, 32 gigs RAM, GTX980TI, etc. And I get this problem as well. It might not be the same problem, but it certainly looks the same.

You could try something - when it happens next time, just wiggle your mouse over the XP screen anywhere. I don't even need to focus on the XP screen usually - just wiggle the mouse. If you have only one monitor, then this is not an issue. But for me this fixes the problem instantly. I go from 5fps to 40 instantly. You could also press any key - the space bar, perhaps. Same effect.

If your problem is hardware (lack of RAM, etc), then I presume this will do nothing. But it works a charm for me until we work out what is really going wrong.

 

[Susu986 76]

Definetely a VRAM overusage problem. If you fly the same aircraft all the time, you can try the reduce some of it's texure sizes. I used to have a GTX 780 with 3 GB of VRAM, and I could ran XP fine, even with orthos, and got around 2,500 MB of VRAM usage (on 'High' of course, which I still do, even though I have a better card since then). The only time this balance got upset when I've purchased the Airfoillabs C172, which was too heavy on my VRAM. So I just went into Photoshop and reduced many of it's textures to half size, and problem solved. But that was before XP 11.10, since then my video card died, so now I have a 1080 and cannot comment if 11.10 had any negative effects or not. Also, I'm not sure about your orthos resolution. Mine are ZL16, with a ZL17 circle surrounding airports. Anything larger than that will seriously challange your VRAM. And I agree, 'High' texture res is mostly indistinguishable from 'Max', however 'Medium' is decidedly bad looking.