FSX-MS FSX never using more than 2GB RAM

[Bert Pieke 7,584]

The OPs question actually was why FSX was not using more than 1900MB of memory.

And given that my FSX install routinely shows less than 1000MB of memory being used in Task Manager, I would suggest that the answer is:

"This is normal, take an Aspirin, get a good night's sleep, and all will be well in the morning." 

[Reader 2,009]

How kind, thank you so much.

[Bert Pieke 7,584]

Sorry, that may have come across as unkind..

Lets try again..

The OPs question actually was:

"Could it be that CPU is a bottleneck which results in limited RAM use?"

And my answer to this question was:

"This is normal.. A faster CPU will not use more RAM."

And that is what I still believe. 

[Taylor Suid 0]

I have 8GB of RAM, AMD Ryzen 3 2200 G Radeon Vega Graphics and 3.50 GHz AND FSX works great with that.

[vortex681 806]

On 26 December 2018 at 1:26 PM, Jim Young said:

This is true but you are talking about virtual address space which is not memory.  Microsoft allocates up to 4GB's of VAS on a 64 bit system and up to 3GB on a 32 bit system that has the /3GB switch.  I was talking about RAM, those memory modules that sit on your MB.  More details are on page 36, AVSIM CTD Guide or around page 21, PMDG Intro Guides.

Yes, but in its simplest form, VAS is just effectively a portion of physical RAM that the OS allocates to a process or program. You said that FSX can use an unlimited amount of RAM but it doesn't matter how much RAM you have, FSX will only ever "see" (use) a maximum of 4GB of it. It doesn't get VAS and RAM.

Edited December 27, 2018 by vortex681

[Jim Young 2,356]

36 minutes ago, vortex681 said:

Yes, but in its simplest form, VAS is just effectively a portion of physical RAM that the OS allocates to a process or program. You said that FSX can use an unlimited amount of RAM but it doesn't matter how much RAM you have, FSX will only ever "see" (use) a maximum of 4GB of it. It doesn't get VAS and RAM.

Totally agree and why I also have P3DV4 which is a 64-bit application that gives me up to 8 terabytes of VAS.

[Bert Pieke 7,584]

47 minutes ago, vortex681 said:

Yes, but in its simplest form, VAS is just effectively a portion of physical RAM that the OS allocates to a process or program. You said that FSX can use an unlimited amount of RAM but it doesn't matter how much RAM you have, FSX will only ever "see" (use) a maximum of 4GB of it. It doesn't get VAS and RAM.

And in a slightly less simple form, VAS is actually a superset of RAM that the OS allocates..

Remember, you can have 2 GB of RAM installed and still run FSX with 3 or 4 GB address space.

So RAM can be bigger or smaller than VAS, the OS does the mapping..

Edited December 28, 2018 by Bert Pieke

[vortex681 806]

10 hours ago, Bert Pieke said:

So RAM can be bigger or smaller than VAS, the OS does the mapping..

Yes, but it can never map/allocate more than 4GB to a 32 bit process.

[Bert Pieke 7,584]

5 hours ago, vortex681 said:

Yes, but it can never map/allocate more than 4GB to a 32 bit process.

Agreed!

[TextRich 88]

For the OP: CPU makes no difference to RAM allocation.  FSX is a 32 bit program and cannot use more than 4 GB of RAM.  Add-on aircraft, scenery, and utilities, - and increasing the aircraft and surface traffic - will bump up the RAM used by the software.  Get a VAS monitor (like the one in FSUIPC - I believe it is available in the free version) and you will get a better idea of how FSX utilizes the 4 GB of RAM that is available for its use.

[Jim Young 2,356]

4 hours ago, BF Bullpup said:

FSX is a 32 bit program and cannot use more than 4 GB of RAM

Please do not use the RAM.  RAM indicates your on-board memory and VAS has nothing, absolutely nothing, to do with on-board member other than it fetches instructions from your RAM.  You are allocated 4GB's of space on your hard drive for each 32-bit application.  See page 26, PMDG Intro Guide.  It has a full explanation of VAS.

Here's more info - https://en.wikipedia.org/wiki/Virtual_address_space

[Jim Young 2,356]

So here is a small extract from the PMDG Guide regarding VAS.  There is more in their guide (also in the AVSIM CTD Guide under OOM's):

"VAS is effectively a preallocation of everything the simulator can potentially access during a flight and will fluctuate over the course of using the simulator as you fly between different areas. Note that VAS is *NOT* the same thing as the “virtual memory” swapfile that you can set the size of in the Windows system options–they are two very different things and having a large virtual memory swapfile does not protect you from the 4GB VAS limit. The mathematical limit itself comes from the definition of “32-bit”–a bit is the most basic data structure in computer science and it can have two values, a 0 or 1, which can mean all sorts of things like true or false, on or off, etc. This is why at the core a computer executes “binary” code. The amount of VAS a 32-bit process can access can be calculated by raising the number of possible values for each bit (2) to the power of the number of bits available (32). So 2/³² equals exactly 4,294,967,296 bytes (not bits). When you do the rest of the conversion math this value comes out to exactly 4 gigabytes of potentially addressable memory for a 32-bit process."

 

"The reason we recommend using a 64-bit operating system like Windows 7 64-bit is due to the fact that it can give Prepar3D.exe that entire 4GB block of VAS. In 32-bit Windows the default is a maximum of 2GB of VAS for P3D and 2GB reserved for the operating system. This can be increased to 3GB for P3D through an edit to the boot environment configuration (“the 3GB switch”), but this is still 1GB lower than you’ll get with the 64-bit version of Windows and it makes both OOMs more likely and OS crashes more likely because it reduces the amount of VAS the OS itself has to work with. 32-bit versions of Windows can also only ever access 4GB of total physical memory, so if P3D is using 3GB itself, there’s not much there for the OS and other applications. 64-bit Windows does not have this limit and with a lot of RAM you can essentially run as many other applications outside of P3D (browser, weather apps, flight planners etc) as you want with no effect on the system. There is literally no reason not to run the 64-bit version of Windows 7 on an P3D simming PC."

[Luke 782]

They're using a very poor choice of words.

FSX doesn't preallocate or memory-map all potential resources; if it did then no one could run an FSX installation with more than 4GB of scenery. This is trivially supported by the fact that OOMs can occur late into a flight when the destination scenery is loaded, if it was all preallocated then you'd get an OOM right at the beginning and never again.

Preallocation, for what it's worth, is the right way to go. What excites me about 64-bit is that P3Dv4 should memory map everything into RAM. It might use 30-40GB of VAS, but the operating system is smart enough to swap the necessary resources in and out of physical RAM as needed. I'm curious to see if LM will eventually go down that road. The startup times might be nasty.

Cheers!