Potential Stratus Layer FPS Bug

[mrgreen9]

Hi guys!

 

I've noticed a peculiar issue with the stratus layer in particular, causing a significant FPS drop from around 50-70, down to 15. I'm also able to reproduce it on my end.

 

Before I get to the steps for reproduction, I should mention I'm running the latest drivers for my GTX 780, with a fresh install of X-Plane 10.40r3 with no other active mods. The same problem also occurs in 10.36.

 

Here we go:

1. Load up a fresh instance of X-Plane

2. Choose a default plane and location - in this case I've selected the default 172 at KSBP

3. Time of day doesn't seem to be a major factor, so try it midday

4. Create a Stratus layer with a base of 3000, and tops of 5000 (this doesn't have to be exact, it could be 3010 and 5010)

5. Exit the weather screen and let the weather load in. (At this point everything is fine)

6. Now go back to the weather screen, and bump the both the base and tops, down by 1000 (base 2000, tops 5000)

7. Now when you exit the weather screen, there should be a slight delay, and once the weather starts loading in there should be an FPS hit

 

I've also figured out how to correct the performance hit; simply go back to the weather screen and change the Stratus layer to "clear," then close the weather screen. Once the weather has cleared, simply go back to the weather screen and load the Stratus layer back in - and you should be fine as long as you don't bump the cloud base and tops up or down.

 

Now there are a few conditions for the problem to occur;

1. Only occurs with Stratus layer

2. Cloud draw distance at least half way full*

3. Overcast Quality needs to be atleast Medium

 

*Now here's something weird about the draw distance; I'm only able to recreate it at around 40% full, but for the sake of testing, set it to 50% as it makes the frame rate drop more obvious.

 

Let's get to the real geeky stuff . I've monitored my CPU, GPU usage and VRAM usage. The GPU clock speed and usage drop significantly - for some reason the usage drops from 70% to 50%, and clock speeds drop from 1189Mhz to 745Mhz. The moment I disable SilverLining fromt the plugin menu, everything goes back to normal - this, or simply clear the weather and reload the stratus layer with SkyMaxx. Please see the provided screenshots with FPS and system usage.

 

I'm really hoping someone else is able to reproduce the potential bug. Please let me know which log files to attach as I'm not familiar with X-Plane log files and their respective locations. I'm hoping my little investigation helps.

 

Specs:

i7-4790k

16GB RAM

GTX 780 3GB

Driver 355.98

Windows 8.1

 

Regards

 

EDIT: Forgot to attach the screenshots  The first shows normal scenario with performance results, the second shows the bug scenario, and the third shows scenario with SkyMaxx disabled. Please bear in mind that this problem only occurs if you go back and edit the stratus layers with them already loaded in. To avoid the issue, make sure to clear the weather and then alter the layer altitude. There is a potential that this problem may also occur when any weather engine tries to generate weather (if assuming stratus layers are updated mid flight), but this would be pure speculation at this point.

Edited September 28, 2015 by mrgreen9

[sundog]

Here's what's happening.

 

SkyMaxx Pro keeps two copies of the cloud layers around; one for the current weather conditions, and another for the previous weather conditions encountered. This is so it can blend between the two smoothly. Once the current conditions are fully blended in, the previous conditions are disabled - but they are still present in memory.

 

So, you may be tight on memory. Reducing the cloud draw distance may help, or use the workaround you already identified - load up clear conditions, then stratus / overcast, so the previous conditions have nothing in them.

 

I think the next version of SkyMaxx Pro will handle this case better once it's out, but I'll double check.

[mrgreen9]

Hey Frank,

 

Thanks, that makes a lot of sense. Funnily enough it's really hard to reproduce in 10.40r3 than in 10.36.

 

I'm glad to know you guys are aware and addressing it - I cannot wait for the next version!

 

Regards

[mrgreen9]

Here's what's happening.

 

SkyMaxx Pro keeps two copies of the cloud layers around; one for the current weather conditions, and another for the previous weather conditions encountered. This is so it can blend between the two smoothly. Once the current conditions are fully blended in, the previous conditions are disabled - but they are still present in memory.

 

So, you may be tight on memory. Reducing the cloud draw distance may help, or use the workaround you already identified - load up clear conditions, then stratus / overcast, so the previous conditions have nothing in them.

 

I think the next version of SkyMaxx Pro will handle this case better once it's out, but I'll double check.

Hello again, Frank!

 

I thought I'd give a heads-up to the situation; but this probably won't matter given that SkyMaxx V3 is imminent anyway.

 

I remember you saying that I might be tight on memory - I've been monitoring the frame rate hit for a while now, but as a layman with little experience, I cannot see any indication of this, as my memory usage shows no difference at around 4.4GB out of 16GB in use, before and after. The usual thing happens - GPU usage and clock speeds drop, RAM usage remains the same; unless you meant GPU VRAM - in which case this also remains the same (it's a 3GB VRAM card.)

 

Anyway, I've attached screenshots of before and after the bug again, but this time with system RAM and CPU usage too.

 

As for anyone else - the fix is simple just clear the cloud layer, exit the the weather options screen and wait for the weather to clear. It shouldn't occur unless you adjust the cloud layer while it is loaded in. I don't use real-time weather so I don't know, but it's also possible that when weather is automatically generated it might trigger the bug, though this part is speculative since I haven't tried this with real weather.

 

I thought I'd give some more feedback hoping it might come in handy in the future, please don't see this as a complaint! Forgive me if this post seemed pointless, given that SkyMaxx V3 is almost here, which I cannot wait for 

 

Regards

 

EDIT: Screenshot 1 shows normal use scenario at 58FPS, screenshot 2 shows the frame rate drop at 14FPS with GPU, CPU and memory usage.

Edited October 22, 2015 by mrgreen9

[mrgreen9]

I'm glad to report the issue does not occur in V3!