Resizable ReBar & VRAM in the SU2 Beta

[WarGuyCH84]

Yeah, sure, my system is to blame
Everything was running just fine before version .18. Since .18, I’ve noticed a significant increase in VRAM usage. Only after disabling ReBAR and HAGS did things go back to normal.

I’m using the LSZH scenery from MK Studios in MSFS2024, which is particularly demanding due to the high-resolution custom assets and the dense photogrammetry around Zurich. Compared to EDDF or EDDM, which are larger airports but generally better optimized and located in less complex terrain, LSZH puts noticeably more load on GPU and VRAM.

Edit: Just to put that into perspective, LSZH:

EDDF:

EDDM:

[Eyrekt]

Please, for the love of God, Asobo, fix ReBar VRAM utilisation on 2024! It reduces the available VRAM and always causes a VRAM alert while flying over London and New York. i have a 4090 and there is not enough VRAM available to fly a complex addon like the Fenix or PMDG 777.

[Eyrekt]

Asobo, when will you fix ReBar and VRAM in 2024? This silence is unacceptable!

[Storm3823]

ReBAR on in BIOS causes stutters. RTX5090, 9800x3d.
Please, fix it!

[SmotheryVase665]

I’ve had Resizable BAR (ReBar) enabled on my PC since I purchased it. I’ve never had a problem with VRAM utilization on my Intel Arc 770 with either MSFS 2020 or 2024.

Reading some of the recent threads on this forum, I disabled it to see if it made any appreciable difference in 2024.
After a number of test flights with both GA & jets from & to large airports, I saw no benefits to available VRAM or performance by having it turned off, so re-enabled it in BIOS.

Which leads me to the thought that this issue may only affect some graphic card manufacturers - e.g. NVidia - and / or only specific models of graphic cards.

[Eyrekt]

With a 4090, ReBar off cuts FPS in half. Only downside with ReBar on, is the VRAM usage goes up by up to 5GB using payware addons like PMDG or Fenix. I tried flying over London with medium textures and 100 TLOD and 100 OLOD. I was consistently hitting full VRAM usage.

[JensilDsouza]

Hello @KurtVWSims,

My observations and reports are with respect to VRAM getting overutilized on default aircraft with default sceneries with Ultra Low graphics preset on a resolution of 1920x1080.

While I may not have the most powerful system in the world, I own an RTX 3070 with 8GB VRAM and 32 GB of RAM.

I am well aware that a program uses RAM and VRAM inorder for ir run. But as described earlier, the current situation that I am facing with Sim Update 2 Beta build (1.4.18.0), landing is impossible for me, and that too on a default aircraft with default sceneries.

When its comes you taking a dig on my “assesment”, can you justify how a program maxing out all the available VRAM available on Ultra Low graphics preset, with default aircraft with default sceneries is acceptable?

So according to your “explanation”, it doesnt matter what a user’s graphics settings are in the sim, what aircaft a user is flying, and no matter if the scenery is default or payware, the sim will use entire VRAM available.

This directly means that, various graphical options / presets and resolutions provided in the sim are useless. Apparently no matter a user’s graphics settings are, the sim will use entire VRAM just because its available.

And how does your justification on usage of VRAM or even RAM hold up when you introduce payware sceneires and high fidelity aircraft like PMDG or Fenix or ini?

How will you differentiate or justify this overutilization of system resources by the program in these cases? Because right now as per your statements, I can just make out just one point: The program will use all the resources RAM or VRAM that is available, irrespective of individual graphics settings, the resolution and the type of aircraft and airports.

While you may consider this normal (maybe because your system has a lot of VRAM available at its disposal), I call this poorly optimized and inefficient handling and excessive (and unnecessary) usage of system resources by the program.

[KurtVWSims]

@JensilDsouza

When its comes you taking a dig on my “assesment”, can you justify how a program maxing out all the available VRAM available on Ultra Low graphics preset, with default aircraft with default sceneries is acceptable?

There is no need to take it personally or as a dig.

The fact is, the vram is there so the program is using it. Thats all. That is its job.

My points were all to do with this idea you have that the amount of free resources is an indication of performance, its not. At least not on anything other than the very latest hardware. The only reason there would be more free resources is if you weren’t using them. If you’re at minimum, then the minimum appears prefer more vram, or most of your vram, this is all. The fact that it wants more vram doesn’t mean that you’re below spec, it just means you’re not at the max spec (which you already know).

I took the examples out to the extreme to show you the silliness of the argument. I have 16gb, and its usually very full… My system is also running it all pretty smoothly, the fullness of the VRAM doesn’t equal bad performance.

It does not mean that the settings are useless, it just means that it would like to have more vram than you have. But since you don’t, it is using the maximum available in order to make things run smoother. VRAM is very fast stuff, there is literally no better place for that data to be than sitting in VRAM ready to be processed. Or are you suggesting you’d benefit from having to read more stuff in from RAM or from the drive in order to have more free VRAM?

I’m not attacking you. I am trying to get you to change the way you’re looking at the problem.

Nobody is picking on you for having an older card. Just trying to get you to look beyond that VRAM number, because its not the problem.

[JensilDsouza]

@KurtVWSims,

Let me make this clear: I never denied that a program shouldnt use VRAM or RAM for its functioning.

The program is supposed to use the resources available. But how much resources a program is supposed to use is directly connected with how a user sets up their graphics settings within the sim. No person is going to use Ultra graphics preset who has just 4GB or 8 GB of VRAM.

In my opinion, a program is poorly coded, if its maxing out and utilizing on all the available system resources at the lowest posssible graphics settings.

I totally disagree with your statement “If you’re at minimum, then the minimum appears prefer more vram, or most of your vram”, this is again incorrect. When a user reduces their grapics settings, a well optimized prgoram is supposed to reduce the usage of system resources, and not use it all just because it is available.

And i really dont care if you have a 16GB or a 60GB VRAM as that doesnt concern me. My observations here is with respect to overutilization of VRAM with Sim Update 2 Beta build (1.4.18.0). I see no sense in the program using 8.XX GB of VRAM at a default airport with default aircraft with Ultra Performance preset at 1920x1080 resolution.

As said earlier, with Sim Update 1 Beta builds, I have had flawless flights with “2020 version of PMDG 777-300ER” with some payware airports. Whats happening right now with the latest beta build is not supposed to happen, not just on my system, but on anyones irrespective of VRAM capacity.

I kindly request you to go through the threads: VRAM Performance Regression - Sim Update 2 Beta | MSFS 2024 / Install, Performance & Graphics - Microsoft Flight Simulator Forums and ReBar using too much VRAM - Sim Update 2 Beta | MSFS 2024 / Beta Discussion - Microsoft Flight Simulator Forums

And again, I am sorry to say, your replies are just trying to justify this poorly optimized, inefficient handling, and excessive and unnecessary usage of system resources by the program just because your system has more VRAM available and you dont get the issues which I have pointed out here.

[KurtVWSims]

@JensilDsouza

I totally disagree with your statement “If you’re at minimum, then the minimum appears prefer more vram, or most of your vram”, this is again incorrect. When a user reduces their grapics settings, a well optimized prgoram is supposed to reduce the usage of system resources, and not use it all just because it is available.

You should be honest here and say

“I believe that when a user…”

You believe that to be true, but you’re mistaken. Since your card is several years old, there is no setting available that get VRAM demand low enough to use less than your 8GB. That’s whats going on here.
And thats ok. Your 8gb isn’t enough… My 16gb isn’t enough. I’m not running maxed settings either.

MSFS for 40 years (believe me I know, I’ve been around the whole time) has been the one program that will smash even the best current hardware. It is extremely demanding, and even on a 50xx series card there are struggles.

Part of that likely is due to some poorly optimized code – You’re not wrong about that. But part of it is just the demands of what the software is trying to do. Typically a new version of MSFS will crush even the biggest baddest machines for the first 2 years after release, and then from there on out hardware comes along that can mostly handle it… And then right about the time everyone has it running smooth a new version comes along and we start all over.

Thats been the rules of the road all the way back to 1982 when I bought my first copy of it.

Anyhow – coming full circle, yeah, poor optimizations… Yep, server hosting everything is a big factor in many people’s poor experience… There are lots and lots of problems. VRAM is not all the problems. VRAM was a lot of the problems… Maybe there are still some issues with the utilization of it, but its much improved, and those improvements may not change how much utilization occurs… It changes how efficiently that utilization occurs (my point from the first response), but not necessarily the amount.

I’m bailing out for tonite. Sorry I’ve been unable to effectively explain what I’ve tried to explain.

[JensilDsouza]

Hello @KurtVWSims,

I appreciate and respect your involvement and expertise with MSFS, and I have been involved since FSX days.

But I am still not convinced about your explanation on pointing out how my “old card” is responsible for these issues I am pointing out.

This same “old card” as you are calling out, was performing better with Sim Update 1 Beta builds, than what it is performing now with Sim Update 2 Beta build (1.4.18.0). This is something that has been happened post the latest beta build for me.

I know and I am well aware that MSFS is extremely demanding and resource hungry, but all I am trying to say here is when a user reduces the graphics settings, there has to be a reduction in system resource usage as well.

If that is not happening, then it is an issue with the program and not the card. And I dont expect my VRAM usgae to drop to 0 with Ultra Performance preset, rather I expect to see a reduction in VRAM utilization.

Also, I disagree with you telling: “VRAM utilization is much improved”. This clearly isnt the case with this current Beta build atleast. VRAM utilization has been worse for people with RTX 3060, 3060Ti, 3070, 3070Ti and even some RTX 4070 and 4080 cards as well on Sim Update 2 Beta build (1.4.18.0).

Instead of calling out our cards old and “supporting the poor optimzation of the program”, please make an effort to get this issues raised with the dev team, so that they acknowledge the issue, incorporate our feedback in the next beta build and in the final Sim Update 2 stable build release.

Thank you and good night.

[edekadesgrauens]

Why arguing so much guys?
The situation is simple: Your card with 8 GB is ■■■■ for modern demanding games, no matter what resolution and settings and no matter how much you do not want it to be that way and i promise you that you will buy a new card soon.

Is MSFS a well-oiled super optimized engine like the id tech engine of DOOM?
No!

Are most other games as good as a id tech engine?
No!
(Btw, with the id8 engine, the new Doom will kill your card also)

So the conseqence is to decide to keep playing older and/or not-so-demanding games or to buy something that can handle modern tech (which is often not very well optimized) or suffer and cope forever.

No offense to you personally mate.

[hobanagerik]

I would agree that having only 8GB of VRAM is going to cause issues in future, and would be unusable for me now, hence the 3090.

What I would add though is that the sim should be able to operate within those constraints but only if you understand, and accept that it will never look as good as it would with more VRAM available.

You can’t fit a quart into a pint pot, and any fantasy thinking that one should expect the same experience with 8GB as you would with 24GB is unhealthy, and would put unrealistic demands on Asobo to achieve something they can’t.

What I would also hope is that Asobo’s attempts to continue to make 8GB, or even 16GB cards a viable prospect, whatever gymnastics they need to do will not affect more capable cards. By all means juggle what you have in memory at any one time, but don’t set an arbitrary upper limit that affects all users. Make more effective use of better hardware, while juggling what you can have in VRAM at any one time for less capable cards.

[TenPatrol]

@Storm3823

ReBAR on in BIOS causes stutters

It’s not true that enabling Resizable BAR in BIOS always causes stutters - it depends on your hardware combo, drivers and Windows settings.

MSI X870E Carbon WIFI, Ryzen 7 9800X3D, G.Skill 64GB DDR5 6000 CL26, RTX 4090 Gigabyte Gaming OC.

edit
On some setups disabling Resizable BAR (for example in the BIOS) can reduce VRAM usage during gaming. I tested it briefly on my RTX 4090 and saw VRAM use drop by about 500 MB to 1 GB - so only a minor gain. That’s why I leave Resizable BAR enabled: one, the difference is negligible; and two, it’s really Asobo who should optimize the game, not us who need to disable Resizable BAR.

[JensilDsouza]

@edekadesgrauens,

I have simply pointed out my observations with respect to excessive VRAM usage on Sim Update 2 Beta build (1.4.18.0).

You want to call these obsrvations as an argument?, the choice is yours.

I am well aware of my what my GPU is capable of rendering, based off the amount of VRAM available. If you carefully read my posts, I am not expecting Ultra Graphics on my RTX 3070 with 8GB VRAM.

All this while, I am only calling out that even my lowest graphics settings with minimal resolution, the VRAM usage is unacceptably high (when it shouldnt be).

Also, with my same 8GB VRAM, I was able to fly “2020 version of PMDG 777-300ER” on Sim Update Beta 1 builds flawlessly without these unrealistic and excessive VRAM usage.

Also, let us keep this discussion inline with the performance of MSFS 2024. I didnt highlight about the performance of DOOM or any other game for that matters, and that is not the point of these posts.

As per requirements posed by Microsoft / Asobo here: Microsoft Flight Simulator 2024 PC System Requirements, my system meets the Recommended Specifications.

Also, I will buy a card, when I want to buy a card, not when devs of this sim decide to unrealisitically increase VRAM consumption. Again, its not just me reporting these excessive VRAM usage, there are people with RTX 3060, 3060Ti, 3070, 3070Ti and even RTX 4070 and 4080 cards as well on Sim Update 2 Beta build (1.4.18.0) who are facing these issues.

If you are pointing out that my 8GB VRAM RTX 3070 GPU is “old”, and cannot handle this sim, then maybe you need to put out a word to Microsoft / Asobo to revise the Recommended Specifications for Sim Update 2 build, so that people with “old RTX 3070 GPU’s” according to you dont purchase this sim or game.

[hobanagerik]

@JensilDsouza

Also, with my same 8GB VRAM, I was able to fly “2020 version of PMDG 777-300ER” on Sim Update Beta 1 builds flawlessly without these unrealistic and excessive VRAM usage.

Let’s assume for a moment that this “excessive” usage of VRAM is not an error, or bug as such. What do you think is being committed to memory that shouldn’t be? I’m assuming a large part of that will be textures, and the like. So if they aren’t in memory, where would they be? Main memory waiting to be sent to VRAM to be displayed I would assume also.

[ExtraPilot6480]

@KurtVWSims

Memory is for using… RAM, VRAM doesn’t matter.

@KurtVWSims

Having it and not using it is not efficient, no matter how you slice it.

This doesn’t fit with my situation.

I have GTX1080Ti, with 11Gb of VRAM. My system is using less than 1GB before I start the sim. I use Afterburner to check my performance after the flight, so I get an accurate correlation between the fps and VRAM.

• The best scenario I have is when my VRAM usage is less than 7Gb, that is with 4GB of headroom. I get above 30fps (in VR), and a fairly good performance (though well below FS2020).
• If when I start a flight the VRAM usage is in the range 7 - 8GB (or the usage creeps above 7GB mid-flight), the performance starts to noticeably degrade (25-30fps), with regular microstutters starting to appear, even though I should have over 3Gb headroom.
• If when I start a flight the VRAM usage is above 8GB (or the usage creeps above 8GB mid-flight, especially on landing), the performance becomes abysmal with macrostutters every time I turn. At this point my fps is 20 or less. Even at 9GB I should have 2Gb of headroom, so the sim is not using the full extent of my VRAM, but is still limiting my performance significantly.

This has been the same for me over several months, with just a few exceptions (eg the Daher TBM930 has poor performance no matter the VRAM usage). I have assumed the drop in perfromance is due to the sim shuffling data around early to avoid running out of VRAM in the near future, which is a sensible thing to do.

So for me, performance is affected well before the VRAM runs out. If the sim did use the full VRAM, it would be unplayable on my system.

[JensilDsouza]

Hello @hobanagerik,

I agree that 8GB VRAM with any GPU will causes issues in the future, depending on the titles.

In all my points made above, I am just highlighting that the current Sim Update 2 Beta build (1.4.18.0), is overutilizing available VRAM. The weird part is, the VRAM is getting overutilized in default aircraft with default airports with Ultra Performance graphics settings in my sim.

And as a person who has been flying over a decade, this behavior from the sim doesnt look right. My expectation is to see a reduction in VRAM utilization when my settings are at the lowest at default airports with default aircraft.

If Microsoft / Asobo has suddenly decided that GPU’s with 8GB of VRAM can no longer run the sim, then that is something that has to be notified to the MSFS 2024 flight simmers.

I can still see some people who are aviation enthusiasts buying a copy of this sim just to see that their system is meeting the minimum system requirements outlined by Microsoft / Asobo.

[hobanagerik]

@JensilDsouza

My expectation is to see a reduction in VRAM utilization when my settings are at the lowest at default airports with default aircraft.

That would follow. Reduce what you are sending to the card, and in theory at least there should be a corresponding drop in committed memory usage. But it would depend on what settings were reduced I expect. Lowing the resolution of the display would be one. Lowering the quality of textures, and reducing the TLOD/OLOD settings also, and possibly the off screen terrain caching setting as well, though that one might cause it to fluctuate more as things are constantly shifted in, and out of VRAM as you cast you view about.

[JensilDsouza]

@hobanagerik,

This really a question for devs to answer.
As we all know the textures are “streamed” from Microsoft servers. (This holds true when I am speaking of default sceneries and aircraft).

How Microsoft / Asobo has coded the streaming of textures from the server to the sim is really which the devs can answer.

But when it comes to paywares, the textures are already present in the disk’s, and its just the matter pushing them from the disk to the RAM, and then being rendered via the GPU.

Again, I sometimes even think that the texture streaming functionality may also contribute to some part of VRAM getting utilized.