FSX, Win7 64b and OOM (again)

[Paxx]

It happens about every six months when I am generally flying. Flying KJFK to Philadelphia International (basically the reverse) is fine. The last time this happened was bush flying in Alaska around Tongass after 4 hours or so.

One other area of the sim I have more than a few add-ons close together is London with Aerosoft Heathrow and the London city scenery by Aerosoft also (iirc). I had an OOM there once in the PMDG 747, back when I was on Win7 64b RC installed over Vista 64b. I think it happened around LFPG once back then also. These incidents were not repeatable and I fly in and out of EGLL, LFPG, KJFK regularly both CA and GA.

Other than that my OOM problem is pretty rare.

[Rohan_Nair]

Try reducing your settings a wee bit. Sometimes, you have to make sacrifices.

[Paxx]

Rohain I like you, and I know you mean well. You are also correct.

But I had a nice laugh. At myself mostly. I guess I should have warned you that I am somewhat crazy and enjoy 'breaking' FSX.

The OOM error I am having, under what are NOT typical conditions for most users, are intentional. I have been looking for a place in the sim that would let me recreate with some consistency this error for about a year now, maybe a little longer. FSX for me performs splendidly over 99.9999...% of the rendered world.

This all came about going back, what's it been now, 4 years since FSX was released. At that time I was on a 32bit operating system (Vista) and experienced the typical 32 bit OS OOM errors common even today for some users. This was when the /3G Switch concept came into being for FSX users and N4gix's Wiki on the subject helped me to understand and fix that problem. Things ran great on that older system and I promised myself to go 64 bit with my next computer.

Step ahead about a year or so and I built my current system with, at the time, Vista 64bit. Ok no /3G switch, tons of RAM bing-bang-boom everything is great, fly as normal (airliner and bush mostly). Then lo' and be'hold ... Emeril Lagasse BAM! FSX OOM error on a 64 bit OS, flagged large address aware blah blah blah.

Now I wasn't depressed about it. I wasn't concerned. It didn't repeat, I reloaded and tried. It didn't happen again for months. By which time I was on Win7 64b RC (Release Candidate). Now at the time being on a beta OS, lot's of very new FSX add-on software, many new video driver/system driver releases as usual with a new OS - I figured hey it's buggy. Are I not a genius?

Anyway, step ahead a bit more to last fall. I blanked all my hard drives, fresh installed Win 7 Ultimate 64bit retail, fresh installed FSX and everything else yadda yadda. All was good in candy land.

Then back in November, FSX OOM error.

Again. See first post of this thread.

Couldn't get it to repeat. I was so flabbergasted I didn't even get a SS. This cannot be, this breaks the damn FSX time continuum.

I wasn't mad, I wasn't angry. By this time I know it won't get fixed, Aces being gone and all, if it even is an FSX bug. Frankly it is so rare for me, it is probably something with my system, no one else has reported this issue on a 64 bit OS that I am aware of. I made this thread last November to raise the issue and see if anyone else had experienced the same. I also made this thread, and recently posted to it, for my own reference, a 'Bug Log in the Cloud' if you will.

Now I have found a 'spot' to toy with this bug and maybe narrow it down although I doubt I will be the one narrowing it down. I simply do not know enough about programing to do so. For me it is fun to ponder and test such things though, and I'll probably learn something new along the way. Another thing I will have to do is find another 'spot' too. There cannot be just one. Perhaps some FTX PNW, a few FTX airfields and whatever detailed aircraft I can fly into and around the area will be installed on my setup (for 'spot' exploration of course). Having been a Flight Sim user since '93, I kinda have the whole flying thing down, so I do other crazy things sometimes with the software and the hardware it runs on - for fun.

So take no offense that I laugh, it is me that I laugh at. Go ahead - laugh at me too. Rest assured I enjoy FSX to the utmost and it performs well on my system. You'll see some screen shots every once in awhile over in the other forum.

[Rohan_Nair]

In short, you have a very experimental nature.

[Paxx]

Further testing reveals ....

DA 42 from KJFK to KPNE (reverse course to above) 55% RAM at takeoff 70% RAM circling Manhattan and the diminishing RAM use on the way SW to KPNE ending with 60% on the ground at Philadelphia NE. No OOM error.

Reboot system.

FSX default Cessna 172 (w/Glass cockpit) KPNE to NYC. 43% Ram usage on the ground at KPNE. 53% above Trenton. 67% RAM usage when Manhattan pops into view (about 40 miles SW NYC). 82% circling Statue of Liberty. Low and slow over Central Park 86% OOM error. Had to spam views/pan camera quite a bit.

Reboot system.

PMDG 747 400X from KPNE to Boston Logan. Logan is default scenery (except surrounding UTX/GTX). Passing over Statue of Liberty @ 6500' AGL +/-, 79% RAM usage. 84% usage on approach to Logan. 78% on the ground. No OOM error. Yes I spamed views all the way. So higher is better, I guess. Have to wonder if my LOD=8.5 might have something to do with this, although in the past my LOD has been default 4.5 iirc when I got the 64b OOM error.

[Paxx]

In short, you have a very experimental nature.

Yeah. You wouldn't want me around the Cern Accelerator, we would discover something.

Probably a bug.

[Paxx]

Well after some more testing which I won't go in to I believe I have come up with why FSX will get a OOM error even on a 64 bit Operating System.

32bit applications are limited to 4GB total address space per application even if flagged Large Address Aware. My previous understanding was that once flagged an app would use whatever memory the OS had available. I was wrong in my understanding. There is a limit. I have been exceeding this limit. Ok that problem (my misunderstanding) solved.

Now how you may ask does Paxx exceed a 4GB limit with just FSX running? That must be a lot of add-on scenery and maxed out slider bars. Well that is part of the reason although my sliders are not maxed (about 3/4 generally speaking). During testing I still found it hard to believe I was exceeding 4GB (once I got the Duh moment out of the way - see above). Yes I have a lot of detailed scenery and was using detailed aircraft, lots of AI traffic (ground/air) and a scenario that brought all these 'RAM loads' together at the same time, but 4GB is A LOT of RAM (still). Something seemed to be missing.

Further looking into the problem I came upon this tidbit from a tech forum.

"If you had 4GB of system ram and a 1GB video card under a 32 bit operating system, each individual program could only use 3GB of that system ram (due to the video card using 1GB of address space) However there is something else most people are NOT aware of.
Under DirectX 9.0C (and lower) video card ram must be duplicated into system ram. That means if you're running on the highest settings with your new shiny 1GB video card - that 1GB of video memory must be duplicated leaving you with only 2GB left for your game.

You just went from 4GB to 2GB, only considering a single 1GB video card. Things only get worse in SLI and crossfire.

Under 64 bit you wouldnt have lost that initial 1GB of ram to the address space, so you'd have 3GB of usable ram, with 1GB used in DX9.0C games. All of a sudden those modern games which border on 1.5-2GB of ram usage are playable, without your system running like a dog.

Side note: It should be noted that DX10/10.1 does not duplicate video memory into system ram. DX10 actually helps to alleviate this issue, if your system is powerful enough to run games in DX10. " - mussels, TechPowerUp Forum.

What struck me about the above statement was the "... Under DirectX 9.0C (and lower) video card ram must be duplicated into system ram." part. I was unaware of this. I haven't verified this statement yet, but I have reason to suspect it is true. The reason being that 1) I have two 1GB video cards and 2) this would certainly explain why I felt something was missing, i.e 2GB of available RAM address space for FSX. I can believe I exceeded 2GB of the remaining address space for FSX. I think.

I'll have to look into it more of course. I'm not sure yet if I 'lose' 1 or 2 GB of space with the cards because of how they are configured when using FSX, but I did run a test (the same test described in the Update post) with DX 10 enabled. RAM usage, as reported by the G15 keyboard display, was about the same, but it took far longer, about 1.5 hours., for me to load/spam/pan enough additional views to induce the OOM error. Loading about 8 outside spot views on the second monitor finally put FSX up to its 4GB limit and then the now familiar OOM message. I'm guessing at this point of course, one test does not make an accurate study.

Switch back to DX9, redo nhancer etc., fly the OOM route, and sure enough, a quick OOM as described in my previous tests.

So to sum up.
1) FSX has a hard cap on the amount of memory it can use - 4GB.
2) If you try hard enough you can exceed this limit.
3)

[kumara]

Hello Paxx,
I resurrect this thread I find most interesting since it's almost three days I'm attempting to get out fromBudapest to Munster VOR to VOR at 6000', and no matter if I try to disable Budapest scenario (AS) as soon as I cross the Czech border and enter Germany VFR (AS) I get the same results. Of course I can always fly out of Buda and go to Trieste, or Moscow, but as you rightly pointed out, it would be more interesting if we can find some possible solution.

I also made some consideration: even if the OOM panel is open, FSX keeps running even with corrupted or not loaded textures; we would need something to free or defrag the Graphic card memory assignments, as this I deem it may help: if we're able to do this, then we should find a way to bypass the infamous panel, so we can continue flying in a jammed out texture world, possibly. As it is now the problem is that when you close the OOM panel FSX will also close, and as I said it still runs, albeit not loading the new textures anymore (VC remains, if you do not switch views).

In any case definitely IMO it seems to be a problem with the infamous graphic engine used and how it deals with the VRAM memory.
If someone will come up with a fix for this, I will not feel compelled to switch to ne P3D v.2 using DX11+ and a 64bit app.

S!

[Paxx]

Sorry for the delayed reply. I sincerely doubt this issue will be fixed with a patch/mod, not because it's impossible but because there is no ROI for MS at this point for this issue. If an independent were to develop a patch/mod for this issue, they would most likely be able to sell it to many who have the issue.

The only solution I have found (for me) is to slightly lower AI traffic and the LOD setting if I plan on flying into one of my "problem areas", which are very few. I even re-read this thread tonight and tried my Philly-NYC route again (Cessna Mustang), hoping Win 7 updates/GPU driver updates had resolved the issue. Nope, OOM as usual.