PSA: X-Plane is a total liar about VRAM usage

Post Reply
Tim Krajcar
Posts: 503
Joined: Mon Jan 24, 2011 11:41 am
Location: KPDX
Contact:

PSA: X-Plane is a total liar about VRAM usage

Post by Tim Krajcar »

I've been having a reoccurring issue with X-Plane (v10) where, with no identifiable cause, my FPS would drop to 1. Even saw 0.15 at one point. Now, this is textbook behavior for VRAM exhaustion, but with a 1080, I thought that was unlikely, especially when I looked in Rendering Settings and saw X-Plane reporting as using "2823.11 meg" of VRAM. Since a 1080 has 8192MB available, clearly that wasn't the problem, so I spent time troubleshooting other things, disabled threaded optimization, blah blah.

But as it turns out, X-Plane is a complete and total liar about VRAM usage! It happened again on my stream last night, so I did some more research, and found other people running into severe FPS drops that recommended using GPU-Z to monitor VRAM usage. Turns out that, when sitting on the ground at one of the MisterX airports, my VRAM usage reported by X-Plane was 4800mb, but GPU-Z reported 7890mb in use! So, enough that any random textures or distant airport scenery loading in would push me over the limit.

I've now reconfigured to lower max texture size to 'Very high' instead of 'Extreme', and am comfortably under the limit. The good news is the sim doesn't look too different, plus I had experimented with world2xp but found that it murdered my FPS - now that I have more VRAM available, I can have that installed and the sim looks better than before.
Tim Krajcar
Live streams at http://twitch.tv/Tim_PE
View past flights on YouTube
stevekirks
Posts: 589
Joined: Wed Oct 01, 2014 6:00 pm
Location: KSGF
Contact:

Re: PSA: X-Plane is a total liar about VRAM usage

Post by stevekirks »

Nice catch. I think the "reported VRAM" usage in XP is from the texture settings. There's other factors like the raw Windows overhead plus any other loads on the card like encoding for the stream.

Thoughts?
Steve Kirks (sKirks on Twitch)
KSGF--I-10 rated
Student Pilot
I invented the Alphabet Challenge, what's your excuse?
Alphabet Challenge
rtataryn
Posts: 344
Joined: Wed Mar 04, 2015 10:19 pm
Location: Spokane, WA

Re: PSA: X-Plane is a total liar about VRAM usage

Post by rtataryn »

Tim, is the frame rate drop only when connected to PE, or is it all the time?
Rod
PPL, Instrument, ASEL, ASES
2013 Cirrus SR22T N877MS
2018 Icon A5 N509BA
1946 Piper J3 Cub N7121H
1942 Stearman N2S N6848
Tim Krajcar
Posts: 503
Joined: Mon Jan 24, 2011 11:41 am
Location: KPDX
Contact:

Re: PSA: X-Plane is a total liar about VRAM usage

Post by Tim Krajcar »

stevekirks wrote:Nice catch. I think the "reported VRAM" usage in XP is from the texture settings. There's other factors like the raw Windows overhead plus any other loads on the card like encoding for the stream.
Yeah, a Redditor also suggested it may have been a leak/bug of some kind.
rtataryn wrote:Tim, is the frame rate drop only when connected to PE, or is it all the time?
Uncertain, I don't think I ever encountered it when disconnected, but I don't think I disconnected while it was occurring either.
Tim Krajcar
Live streams at http://twitch.tv/Tim_PE
View past flights on YouTube
joomie
Posts: 42
Joined: Fri Nov 18, 2016 6:49 am

Re: PSA: X-Plane is a total liar about VRAM usage

Post by joomie »

I had always the same impression but never
proofed it. Just stopped trusting the displayed
value and switched to external tools like
Afterburner or GPU-Z.
Thanks for the confirmation!
X-Plane 11.00pb3, Win 10 (64bit), ASUS Z170 PRO GAMING, Intel Core i7 6700K@4.5 GHz, Inno3D iChill GTX 1080 X3 (no OC), 32GB DDR4 RAM, ASUS Strix SOAR sound card, 1.25 TB SSD, SAMSUNG SUHD 55'' TV 3840x2160, TrackIR5.4.2
rtataryn
Posts: 344
Joined: Wed Mar 04, 2015 10:19 pm
Location: Spokane, WA

Re: PSA: X-Plane is a total liar about VRAM usage

Post by rtataryn »

Tim,

If the frame rates return to normal after disconnecting from PE, and you use an iPad with traffic, it may be the IP address in the VSProTrafficRelay.ini file doesn't match the iPad IP address. That will cause significant frame rate drops like you've described.
Rod
PPL, Instrument, ASEL, ASES
2013 Cirrus SR22T N877MS
2018 Icon A5 N509BA
1946 Piper J3 Cub N7121H
1942 Stearman N2S N6848
Tim Krajcar
Posts: 503
Joined: Mon Jan 24, 2011 11:41 am
Location: KPDX
Contact:

Re: PSA: X-Plane is a total liar about VRAM usage

Post by Tim Krajcar »

Not using an iPad with the sim at the moment, but good to keep in mind.
Tim Krajcar
Live streams at http://twitch.tv/Tim_PE
View past flights on YouTube
Post Reply