Increase performance and capacity

Background

Microsoft Windows reserves the upper half of the 4 GB virtual address space of any process for the operating system, and leaves the remaining 2 GB for the application process, including the space for the code pages, the stack, and all dynamically allocated memory.

Thus, Microsoft Windows operating systems support no more than 2 GB of memory usage for one application. The 3 GB feature divides the memory space differently, providing 3 GB for the application and 1 GB for the operating system. This is not a network server limit, but is relevant to users working with large, memory-intensive data sets.

Note: When using the 3GB switch, it is recommended that the computer has at least 3 GB of physical RAM, but 4 GB of RAM is preferred. This will considerably reduce the amount of paging done by the operating system. It is also required that the size of the page file should be 4GB or more.

Important Autodesk does not support or endorse the /3GB switch. In many cases, this customization will cause Inventor graphics to be incorrectly displayed. Instead, we recommend updating to a 64-bit version of Windows.

To set the page file size, right-click My Computer Properties Advanced Tab Performance Settings Advanced Tab click Change in the virtual memory section. Enter 4096 in Initial size box as well as in Maximum size box and click on Set. Click OK.

Enable the feature

You must change your boot.ini file (which is typically located at C:\boot.ini) to have the 3 GB option, as shown below. It is recommended that you copy the original line, and then modify the copied line to add the option and the identifying string. This sets it up so you can choose at start time whether to use the option or not.

Note: The default is to use whichever line is first.

The copied line is show in green (last line), with the modified portions of the line shown in red.

[boot loader]

timeout=30

default=multi(0)disk(0)disk(0)partition(2)\WINDOWS

[operating systems]

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional 3GB" /3GB /fastdetect

Ensure this is working

To insure that Autodesk Inventor is actually allocating memory in the 3 GB range, start Autodesk Inventor. Click Help About Autodesk Inventor. The first line of text under the splash screen image should say: "Autodesk Inventor [release number] - 3GB" If the - 3GB is shown, Autodesk Inventor is successfully using the feature.

Limitations

Each executable must be specially built to enable the larger address space. Only the Autodesk Inventor.exe has been enabled. Other executables shipped with Autodesk Inventor have not been enabled. Most likely, the applications provided by other software vendors have not been enabled to use this feature.

The feature only works on Windows XP. Furthermore, the Windows XP SP1 service pack disabled it. To re-enable it for Windows XP SP1, there is a hot fix from Microsoft that must be applied. To apply that hot fix (q328269_WXP_SP2_x86_ENU.exe), follow the instructions in the hotfix.txt file in the associated zip file. It is not possible to enable the feature on Windows NT, Windows 2000, or Windows 9x.