A program that requests 3 GB of memory is more likely to be able to have more of its memory remain in physical memory rather than be paged out. In this case, the operating system doesn't use any memory in excess of 16 GB.
This behavior is caused by kernel virtual memory space considerations. AWE is a set of application programming interfaces APIs to the memory manager functions that enables programs to address more memory than the 4 GB that is available through standard bit addressing. AWE enables programs to reserve physical memory as non-paged memory and then to dynamically map portions of the non-paged memory to the program's working set of memory.
This process enables memory-intensive programs, such as large database systems, to reserve large amounts of physical memory for data without having to be paged in and out of a paging file for usage. Instead, the data is swapped in and out of the working set and reserved memory is in excess of the 4-GB range. To summarize, PAE is a function of the Windows and Windows Server memory managers that provides more physical memory to a program that requests memory.
The program isn't aware that any of the memory that it uses resides in the range greater than 4 GB, just as a program isn't aware that the memory it has requested is actually in the page file.
The reserved memory is non-pageable and is only accessible to that program. If the server has a redundant memory feature or a memory mirroring feature that is enabled, the full complement of memory may not be visible to Windows. Manage consent. Close Privacy Overview This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website.
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Necessary cookies are absolutely essential for the website to function properly. The Kernel space is common for all applications and the User-mode processes each get their own 2GB address space to work with.
Remember that we only have a 4GB total address space to work with. If we have to allocate an additional 1GB of this address space to the user-mode space, then the System space is cut in half. However, because of the way memory mapping works, cutting the kernel space in half does a lot more than just reducing the address space. Keep in mind that this is only a test server that isn't under any sort of load.
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