Memory usage on 64-bit OS

[valle2000]

But can a 32-bit application running in my 64-bit OS utilize any of the memory above the first 4 GB?

A simple theoretical example. If we pretend the OS uses 1 GB of memory and two 32-bit applications are launched using 3 GB each, can the first program be placed in memory range 2-4 GB and the second in memory range 5-7 GB? Or must they both be placed within those first 4 GB since they are 32-bit and are incapable of allocate any memory above the 1-4 GB range?

Hope you understand how I mean.

[alcattle]

But can a 32-bit application running in my 64-bit OS utilize any of the memory above the first 4 GB?

A simple theoretical example. If we pretend the OS uses 1 GB of memory and two 32-bit applications are launched using 3 GB each, can the first program be placed in memory range 2-4 GB and the second in memory range 5-7 GB? Or must they both be placed within those first 4 GB since they are 32-bit and are incapable of allocate any memory above the 1-4 GB range?

Hope you understand how I mean.

yes although some older programs need a little help with newer 64 bit OS

[ILikeTwins]

But can a 32-bit application running in my 64-bit OS utilize any of the memory above the first 4 GB?

A simple theoretical example. If we pretend the OS uses 1 GB of memory and two 32-bit applications are launched using 3 GB each, can the first program be placed in memory range 2-4 GB and the second in memory range 5-7 GB? Or must they both be placed within those first 4 GB since they are 32-bit and are incapable of allocate any memory above the 1-4 GB range?

Hope you understand how I mean.

The Operating System only really cares that an application is 32bit for the purposes of figuring out how to execute each instruction.

From a memory standpoint the OS just needs to know how much total space an application needs. So in your example the OS sees that it has 12GB total of addresses to use. It uses the 1GB you mention so then it has 11GB free. If you have 2 apps running at 3GB each then it will fit them both in as best it can in the space that is not being used. It may allocate it to spaces 2-4, 5-7, 10-12 etc but it has no restrictions as to where it must put it. In other words it doesn't restrict it to the first 4GB since a 64bit OS can recognize all 12GB.

It actually gets more complicated than that since applications in RAM are in non-contiguous space (basically the application files are stored in all different spots in the memory but the overall usage is the same if you add all the pieces up). For the sake of this example it is fine to explain it the way that I have above

Hope this helps
Twins

Oh and Buetzel you are correct. 32 bit applications are run in an emulator in 64 bit Windows called WOW64 (which stands for Windows 32-bit On Windows 64-bit). I think the name is a little ironic given the game we play hehe

Here is an explanation of the techonology - http://en.wikipedia.org/wiki/WoW64

[HPAVC]

If you set a perfmon condition for 2.5gb you can see that wow hops up there. I only see this when under stupid auction addons race the damn game's addon garbage collection and the memory is take up with buffers that windows is giving it via the wow64 abstraction mentioned below.

If you track the garbage collection in game, the game uses pretty much nothing on the normal 'flying gas can slave setup'. Eventually it will hit 1.5gb, but then you will zone, loot, or what not and it will free up.

My worry on a system with low memory (less than 2gb per wow) is just how much time the game spends in garbage collection and how often.