System virtual address (VA) space on 32-bit systems can become exhausted due to fragmentation. (This issue does not affect 64-bit systems.) Several registry keys can be used to configure memory limits on systems that experience this issue. These memory management registry keys must be explicitly created under the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\Current Control Set\Control\
Session Manager\Memory Management
Windows Server 2008 and Windows Vista: These registry keys are available on 32-bit systems starting with Windows Server 2008 and Windows Vista Service Pack 1 (SP1).
For default memory and address space limits on both 32-bit and 64-bit systems, see Memory Limits for Windows Releases.
The following table describes the memory management registry keys that can be used to configure memory limits. All of these keys have a REG_DWORD type and possible values that range from 0 through 2,048 MB. The default is 0, which means no limit is enforced. Values are automatically rounded up to the next system VA allocation boundary, which is 2 MB on 32-bit systems that have Physical Address Extension (PAE) enabled and 4 MB on 32-bit systems that do not have PAE enabled.
| Key | Description |
|---|
| NonPagedPoolLimit | Specifies the maximum amount of system VA space that can be used
by the nonpaged pool. Under certain conditions, this limit may
be exceeded by a small amount.
|
| PagedPoolLimit | Specifies the maximum amount of system VA space that can be used
by the paged pool. |
| SessionSpaceLimit | Specifies the maximum amount of system VA space that can be used
by session space allocations. |
| SystemCacheLimit | Specifies the maximum amount of system VA space that can be used
by the system cache. Under certain conditions, this limit may
be exceeded by a small amount.
|
| SystemPtesLimit | Specifies the maximum amount of system VA space that can be used
by I/O mappings and other resources that consume system page table entries (PTEs). |
Determining whether system VA space is being exhausted requires the use of a kernel debugger. For more information, see Debugging Tools for Windows.
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Build date: 10/9/2008