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J_J

x64 more than 2GB per process

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Hi, I heard that on windows 64bit you can allocate more than 2GB per process. Did anyone try it? I am developing a server program and really need to bypass the 2GB per process win32 limit. Thanks! JJ

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edit: this wikipedia article on x86-64 probably is the best link:
[on windows x64 (xp, 2003, vista)] 8 tebibytes (2^43 bytes) of "user mode" virtual memory address space per process. A 64-bit program can use all of this, subject of course to backing store limits on the system. This is a 4096-fold increase over the default 2 gibibyte user-mode virtual address space offered by 32-bit Windows.
This of course is limited to the amount of hard disk space/secondary storage

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The following leads me to believe that you can do it.
This 4GB space is evenly divided into two parts, with 2GB dedicated for kernel usage, and 2GB left for application usage. Each application gets its own 2GB, but all applications have to share the same 2GB kernel space.
from The 4GB Windows Memory Limit: What does it really mean? (if the url is malformed google it)

Also slightly relevant:
Behind Windows x64’s 44-bit Virtual Memory Addressing Limit
Comparison of 32-bit and 64-bit memory architecture for 64-bit editions of Windows XP and Windows Server 2003

These were found via googling

[Edited by - thedustbustr on December 29, 2007 3:07:36 PM]

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It depends.
Assuming you're running a 64-bit version of Windows, the following applies:
- 32 bit applications that are not compiled with /largeaddressaware will still be limited to 2GB
- 32 bit applications that are compiled with /largeaddressaware will be able to use up to 4GB
- 64 bit applications aren't limited to either, but can use all the memory available, as said above.

So as long as your application is compiled for 64-bit you don't need to worry about this at all.

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