» Mon May 28, 2012 12:55 pm
Here's a little of the MS explanation for 4gb Tuning - http://msdn.microsoft.com/en-us/library/windows/desktop/bb613473%28v=vs.85%29.aspx -
"On 32-bit editions of Windows, applications have 4 gigabyte (GB) of virtual address space available. The virtual address space is divided so that 2 GB is available to the application and the other 2 GB is available only to the system.
The 4-gigabyte tuning (4GT) feature, formerly called 4GT RAM Tuning, increases the virtual address space that is available to the application up to 3 GB, and reduces the amount available to the system to between 1 and 2 GB.
For applications that are memory-intensive, such as database management systems (DBMS), the use of a larger virtual address space can provide considerable performance and scalability benefits. However, the file cache, paged pool, and nonpaged pool are smaller, which can adversely affect applications with heavy networking or I/O. Therefore, you might want to test your application under load, and examine the performance counters to determine whether your application benefits from the larger address space."
"On 64-bit editions of Windows, 32-bit applications marked with the http://msdn.microsoft.com/en-us/library/windows/desktop/ms680349%28v=vs.85%29.aspx flag have 4 GB of address space available."
Edit: BTW, computer games are large Data Base Management Systems!
If I understand that correctly it means that only 64 bit Windows gets all 4 gig for the game with the system requirements going beyond 4gb (if you have more than 4gb installed RAM) while 32 bit Windows can only allow the game to use 3gb with the last gb reserved for system reqs. Which makes sense because 32 bit can only recognize or address up to 4gb so any more than that is useless with 32 bit Windows.
I'm still trying to figure out what else they could have done, beyond setting the LAA flag, to make the game more efficient. I don't think they taken enough time yet to clean up the memory leaks but if anyone notices an improvement there as well that would be good to know.