32 bit Application physical memory usage under WOW64

When running 32 bit applications under Windows Vista 64bit (using
WOW64), are these applications limited to 4GB of Physical memory for
all applications?

For example, assume a machine has 8GB of physical memory. WOW64
allows 4GB of virtual address space per 32-bit app. I have a 32-bit
application that uses 2GB of memory and I want to run 3 instances of
it. Running these 3 instances should require 6GB of memory. When
running these applications under WOW64, will each of these
applications end up using their own 2GB of PHYSICAL memory, or will
they all share the same 4GB of physical memory with the remaining 2GB
on disk?

They'll each get 4 GB of Virtual Memory Address space. If they're not
LARGEMEMORYAWARE, they'll actually not be able to use >2GB of virtual memory
address space, since that's all they know how to see. Now, what does all
that mean for physical memory? That is entirely up to the operating system
to decide, and is dynamic, depending on what else is happening, and what the
OS (Vista 64-bit in this case) decides is optimal. So, the short answer is,
they are not limited to 4 GB of physical memory. But the longer answer is,
you can't really control how much physical memory they get, that's the job
of the OS.

--
Charlie.
http://msmvps.com/blogs/xperts64
http://mvp.support.microsoft.com/profile/charlie.russel



"Michael" <mrmann87@gmail.com> wrote in message
news:152ea2ba-d82f-442b-ab3c-a9da5e78e008@v20g2000yqm.googlegroups.com...
> When running 32 bit applications under Windows Vista 64bit (using
> WOW64), are these applications limited to 4GB of Physical memory for
> all applications?
>
> For example, assume a machine has 8GB of physical memory. WOW64
> allows 4GB of virtual address space per 32-bit app. I have a 32-bit
> application that uses 2GB of memory and I want to run 3 instances of
> it. Running these 3 instances should require 6GB of memory. When
> running these applications under WOW64, will each of these
> applications end up using their own 2GB of PHYSICAL memory, or will
> they all share the same 4GB of physical memory with the remaining 2GB
> on disk?

Thanks for the answer Charlie!

I assumed this was the case but I just needed a confirmation.

-Mike